CHAPTER 8
CHIMNEYS AND VENTS
Note: Portions of this chapter have been reproduced in their entirety from NFPA 54-2006 (ANSI Z223.1).
801.0 Scope.
The requirements of this chapter shall govern the
venting of fuel-burning appliances.
801.1 Venting of Gas Appliances. Low-heat
gas appliances shall be vented in accordance
with this chapter. Other gas appliances shall be
vented in accordance with NFPA 211 or other
applicable standards.
801.2 Appliances Fueled by Other Fuels.
Appliances fueled by fuels other than gas shall be
vented in accordance with NFPA 211 and the
appliance manufacturer’s instructions.
802.0 General.
802.1 This section recognizes that the choice of
venting materials and the methods of installation
of venting systems are dependent on the operating
characteristics of the gas utilization equipment. The
operating characteristics of vented gas utilization
equipment can be categorized with respect to (1)
positive or negative pressure within the venting
system, and (2) whether or not the equipment
generates flue or vent gases that can condense in
the venting system. See Section 224.0 for the
definition of these vented appliance categories.
[NFPA 54:12.2]
802.2 Specification for Venting.
802.2.1 Connection to Venting Systems.
Except as permitted in Section 802.2.2 through
802.2.6, all gas utilization equipment shall be
connected to venting systems. [NFPA 54:12.3.1]
802.2.2 Equipment Not Required to Be
Vented. The following equipment shall not be
required to be vented [NFPA 54:12.3.2]:
802.2.2.1 Listed ranges. [NFPA 54:12.3.2(1)]
802.2.2.2 Built-in domestic cooking units
listed and marked for optional venting.
[NFPA 54:12.3.2(2)]
802.2.2.3 Listed hot plates and listed
laundry stoves. [NFPA 54:12.3.2(3)]
802.2.2.4 Listed Type 1 clothes dryers
exhausted in accordance with Section
504.3.2. [NFPA 54:12.3.2(4)]
802.2.2.5 A single listed booster-type
(automatic instantaneous) water heater,
when designed and used solely for the
sanitizing rinse requirements of a
dishwashing machine, provided that the
equipment is installed with the draft hood
in place and unaltered, if a draft hood is
required, in a commercial kitchen having a
mechanical exhaust system; where installed
in this manner, the draft hood outlet shall
not be less than thirty-six (36) inches (910
mm) vertically and six (6) inches (150 mm)
horizontally from any surface other than
the equipment. [NFPA 54:12.3.2(5)]
802.2.2.6 Listed refrigerators. [NFPA
54:12.3.2(6)]
802.2.2.7 Counter appliances. [NFPA
54:12.3.2(7)]
802.2.2.8 Room heaters listed for unvented
use (see Sections 924.1 and 924.2). [NFPA
54:12.3.2(8)]
802.2.2.9 Direct gas-fired makeup air heaters.
[NFPA 54:12.3.2(9)]
802.2.2.10 Other equipment listed for
unvented use and not provided with flue
collars. [NFPA 54:12.3.2(10)]
8 0 2 . 2 . 2 . 1 1 Specialized equipment of
limited input such as laboratory burners
or gas lights. [NFPA 54:12.3.2(11)]
Where any or all of this equipment in Sections
802.2.2.5 through 802.2.2.11 is installed so the
aggregate input rating exceeds 20 Btu/h/ft.3 (207
W/m3) of room or space in which it is installed,
one or more shall be provided with venting
systems or other approved means for removing
the vent gases to the outside atmosphere so the
aggregate input rating of the remaining
unvented equipment does not exceed 20
Btu/h/ft 3 (207 W/m 3). Where the calculation
includes the volume of an adjacent room or
space, the room or space in which the equipment
is installed shall be directly connected to the
adjacent room or space by a doorway, archway,
or other opening of comparable size that cannot
be closed. [NFPA 54:12.3.1]
802.2.3 Ventilating Hoods. Ventilating hoods
and exhaust systems shall be permitted to be
111
802.2 – 802.4
used to vent gas utilization equipment installed
in commercial applications (see Section 802.3.5)
and to vent industrial equipment, particularly
where the process itself requires fume disposal.
[NFPA 54:12.3.3]
802.2.4 Well-Ventilated Spaces. The operation
of industrial gas utilization equipment such that
its flue gases are discharged directly into a large
and well-ventilated space shall be permitted.
[NFPA 54:12.3.4]
802.2.5 Direct-Vent Equipment. Listed directvent gas utilization equipment shall be
considered properly vented where installed in
accordance with the terms of its listing, the
manufacturers' instructions, and Section 802.8.3.
802.2.6 Equipment with Integral Vents. Gas
utilization equipment incorporating integral
venting means shall be considered properly
vented where installed in accordance with its
listing, the manufacturers' instructions, and
Sections 802.8.1 and 802.8.2. [NFPA 54:12.3.6]
802.3 Design and Construction.
802.3.1 Minimum Safe Performance. A venting
system shall be designed and constructed so as to
develop a positive flow adequate to remove flue
or vent gases to the outside atmosphere. [NFPA
54:12.1]
802.3.2 Equipment Draft Requirements. A
venting system shall satisfy the draft
requirements of the equipment in accordance
with the manufacturer's instructions. [NFPA
54:12.4.1]
802.3.3 Design and Construction. Gas utilization
equipment required to be vented shall be
connected to a venting system designed and
installed in accordance with the provisions of
Sections 802.4 through 802.15. [NFPA 54:12.4.2]
802.3.4 Mechanical Draft Systems.
802.3.4.1 Mechanical draft systems shall be
listed and shall be installed in accordance
with the terms of their listing and both the
appliance and the mechanical draft system
manufacturers' instructions. [NFPA 54:12.4.3.1]
802.3.4.2 Gas utilization equipment requiring
venting shall be permitted to be vented by
means of mechanical draft systems of either
forced or induced draft design. [NFPA
54:12.4.3.2]
Exception: Incinerators.
802.3.4.3 Forced draft systems and all
portions of induced draft systems under
positive pressure during operation shall be
112
2007 CALIFORNIA MECHANICAL CODE
designed and installed so as to prevent
leakage of flue or vent gases into a building.
[NFPA 54:12.4.3.3]
802.3.4.4 Vent connectors serving equipment
vented by natural draft shall not be connected
into any portion of mechanical draft systems
operating under positive pressure. [NFPA
54:12.4.3.4]
802.3.4.5 Where a mechanical draft system
is employed, provision shall be made to
prevent the flow of gas to the main burners
when the draft system is not performing so
as to satisfy the operating requirements of
the equipment for safe performance. [NFPA
54:12.4.3.5]
802.3.4.6 The exit terminals of mechanical
draft systems shall be not less than seven (7)
feet (2.1 m) above grade where located
adjacent to public walkways and shall be
located as specified in Sections 802.8.1 and
802.8.2. [NFPA 54:12.4.3.6]
802.3.5 Ventilating Hoods and Exhaust Systems.
802.3.5.1 Ventilating hoods and exhaust
systems shall be permitted to be used to
vent gas utilization equipment installed in
commercial applications. [NFPA 54:12.4.4.1]
802.3.5.2 Where automatically operated gas
utilization equipment is vented through a
ventilating hood or exhaust system
equipped with a damper or with a power
means of exhaust, provisions shall be made
to allow the flow of gas to the main burners
only when the damper is open to a position
to properly vent the equipment and when
the power means of exhaust is in operation.
[NFPA 54:12.4.4.2]
802.3.6 Circulating Air Ducts and Furnace
Plenums. No portion of a venting system shall
extend into or pass through any circulating air
duct or furnace plenum. [NFPA 54:12.4.5.1]
802.4 Type of Venting System to Be Used.
802.4.1 The type of venting system to be used
shall be in accordance with Table 8-1. [NFPA
54:12.5.1]
802.4.2 Plastic Piping. Plastic piping used for
venting equipment listed for use with such
venting materials shall be approved. [NFPA
54:12.5.2]
802.4.3 Special Gas Vent. A special gas vent
shall be listed and installed in accordance with
the terms of the special gas vent listing and the
manufacturers' instructions. [NFPA 54:12.5.3]
CHIMNEYS AND VENTS
802.5 Masonry, Metal, and Factory-Built Chimneys.
802.5.1 Listing or Construction.
802.5.1.1 Factory-built chimneys shall be
installed in accordance with their listing and
the manufacturers' instructions. Factorybuilt chimneys used to vent appliances that
operate at positive vent pressure shall be
listed for such application. [NFPA
54:12.6.1.1]
802.5.1.2 Metal chimneys shall be built and
installed in accordance with NFPA 211,
Standard for Chimneys, Fireplaces, Vents,
and Solid-Fuel-Burning Appliances. [NFPA
54:12.6.1.2]
802.5.1.3 Masonry chimneys shall be built
and installed in accordance with NFPA 211,
Standard for Chimneys, Fireplaces, Vents,
and Solid-Fuel-Burning Appliances, and
lined with an approved clay flue lining, a
listed chimney lining system, or other
approved material that will resist corrosion,
erosion, softening, or cracking from vent
gases at temperatures up to 1,800°F (982°C).
[NFPA 54:12.6.1.3]
Exception: Masonry chimney flues lined
with a chimney lining system specifically
listed for use with listed gas appliances
with draft hoods, Category I appliances,
and other gas appliances listed for use
with Type B vents shall be permitted.
The liner shall be installed in accordance
with the liner manufacturer's instructions
and the terms of the listing. A permanent
identifying label shall be attached at the
point where the connection is to be made
to the liner. The label shall read: "This
chimney liner is for appliances that burn
gas only. Do not connect to solid or liquidfuel-burning appliances or incinerators."
802.5.2 Termination.
802.5.2.1 A chimney for residential-type or
low-heat gas utilization equipment shall
extend at least three (3) feet (0.9 m) above the
highest point where it passes through a roof
of a building and at least two (2) feet (0.6 m)
higher than any portion of a building within
a horizontal distance of ten (10) feet (3.0 m).
(See Figure 8-1.) [NFPA 54:12.6.2.1]
802.5 – Table 8-1
TABLE 8-1
Type of Venting System to Be Used
Gas Utilization Equipment
Listed Category I equipment
Listed equipment equipped
with draft hood
Equipment listed for use with
Type B gas vent
Listed vented wall furnaces
Category II equipment
Category III equipment
Category IV equipment
Incinerators, outdoors
Type of Venting System
Type B gas vent (802.6)
Chimney (802.5)
Single-wall metal pipe
(802.7)
Listed chimney lining
system for gas venting
(802.5.1.3)
Special gas vent listed
for this equipment
(802.4.3)
Type B-W gas vent
(802.6, 928.0)
As specified or furnished
by manufacturers of listed
equipment (802.4.2,
802.4.3)
Single-wall metal pipe
(802.7, 802.7.3.3)
Incinerators, indoors
Chimney (802.5)
Equipment that can be
Type L vent (802.6) or
converted to use of solid fuel chimney (802.5)
Unlisted combination gas- and
oil-burning equipment
Combination gas- and solid-fuelburning equipment
Equipment listed for use with
chimneys only
Unlisted equipment
Listed combination gas- and
oil-burning equipment
Decorative appliance in vented Chimney [907.2(3)]
fireplace
Gas-fired toilets
Single-wall metal pipe
(802.7, 926.3)
Direct-vent equipment
See 802.2.5
Equipment with integral vent
See 802.2.6
[NFPA 54: Table 12.5.1]
113
Figure 8-1 – 802.5
2007 CALIFORNIA MECHANICAL CODE
802.5.2.2 A chimney for medium-heat
equipment shall extend at least ten (10) feet
(3.0 m) higher than any portion of any
building within twenty-five (25) feet (7.6 m).
[NFPA 54:12.6.2.2]
802.5.2.3 A chimney shall extend at least
five (5) feet (1.5 m) above the highest
connected equipment draft hood outlet or
flue collar. [NFPA 54:12.6.2.3]
802.5.2.4 Decorative shrouds shall not be
installed at the termination of factory-built
chimneys except where such shrouds are
listed and labeled for use with the specific
factory-built chimney system and are
installed in accordance with manufacturers'
installation instructions. [NFPA 54:12.6.2.4]
802.5.3 Size of Chimneys. The effective area of
a chimney venting system serving listed gas
appliances with draft hoods, Category I
appliances, and other appliances listed for use
with Type B vents shall be in accordance with
one of the following methods [NFPA 54:12.6.3.1]:
(1) Section 803.0. [NFPA 54:12.6.3.1(1)]
(2) For sizing an individual chimney venting
system for a single appliance with a draft
hood, the effective areas of the vent
connector and chimney flue shall be not less
than the area of the appliance flue collar or
draft hood outlet or greater than seven times
the draft hood outlet area. [NFPA
54:12.6.3.1(2)]
(3) For sizing a chimney venting system
connected to two appliances with draft
hoods, the effective area of the chimney flue
shall be not less than the area of the larger
draft hood outlet plus 50 percent of the area
of the smaller draft hood outlet, or greater
than seven times the smallest draft hood
outlet area. [NFPA 54:12.6.3.1(3)]
(4) Other approved engineering methods.
[NFPA 54:12.6.3.1(5)]
(5) Chimney venting systems using mechanical
draft shall be sized in accordance with
approved engineering methods. [NFPA
54:12.6.3.1(4)]
FIGURE 8-1 Typical Termination Locations for
Chimneys and Single-Wall Metal Pipes Serving
Residential-Type and Low-Heat Equipment.
[NFPA 54: Figure 12.6.2.1]
114
802.5.4.1 Where an incinerator is vented by
a chimney serving other gas utilization
equipment, the gas input to the incinerator
shall not be included in calculating chimney
size, provided the chimney flue diameter is
not less than one (1) inch (25 mm) larger in
CHIMNEYS AND VENTS
equivalent diameter than the diameter of the
incinerator flue outlet. [NFPA 54:12.6.3.2]
802.5.4 Inspection of Chimneys.
802.5.4.1 Before replacing an existing
appliance or connecting a vent connector to
a chimney, the chimney passageway shall be
examined to ascertain that it is clear and free
of obstructions and shall be cleaned if
previously used for venting solid- or liquidfuel-burning appliances or fireplaces.
[NFPA 54:12.6.4.1]
802.5.4.2 Chimneys shall be lined in
accordance with NFPA 211, Standard for
Chimneys, Fireplaces, Vents and Solid FuelBurning Appliances. [NFPA 54:12.6.4.2]
802.5.4.3 Cleanouts shall be examined to
determine they will remain tightly closed
when not in use. [NFPA 54:12.6.4.3]
802.5.4.4 When inspection reveals that an
existing chimney is not safe for the intended
application, it shall be repaired, rebuilt,
lined, relined, or replaced with a vent or
chimney to conform to NFPA 211, Standard
for Chimneys, Fireplaces, Vents, and SolidFuel-Burning Appliances, and shall be
suitable for the equipment to be attached.
[NFPA 54:12.6.4.4]
802.5.5 Chimney Serving Equipment Burning
Other Fuels.
802.5.5.1 Gas utilization equipment shall not
be connected to a chimney flue serving a
separate appliance designed to burn solid fuel.
802.5.5.2 Where one chimney serves gas
utilization equipment and equipment
burning liquid fuel, the equipment shall be
connected through separate openings or
shall be connected through a single opening
where joined by a suitable fitting located as
close as practical to the chimney. Where two
or more openings are provided into one
chimney flue, they shall be at different
levels. Where the gas utilization equipment
is automatically controlled, it shall be
equipped with a safety shutoff device.
802.5.5.3 A listed combination gas and solidfuel-burning appliance connected to a single
chimney flue shall be equipped with a manual
reset device to shut off gas to the main burner
in the event of sustained backdraft or flue gas
spillage. The chimney flue shall be sized to
properly vent the appliance.
802.5 – 802.6
802.5.5.4 A single chimney flue serving a listed
combination gas and oil-burning appliance
shall be sized to properly vent the appliance.
802.5.6 Support of Chimneys. All portions of
chimneys shall be supported for the design and
weight of the materials employed. Listed
factory-built chimneys shall be supported and
spaced in accordance with their listings and the
manufacturers' instructions.
802.5.7 Cleanouts. Where a chimney that
formerly carried flue products from liquid-or
solid-fuel-burning appliances is used with an
appliance using fuel gas, an accessible cleanout
shall be provided. The cleanout shall have a
tight-fitting cover and be installed so its upper
edge is at least six (6) inches (150 mm) below the
lower edge of the lowest chimney inlet opening.
802.5.8 Space Surrounding Lining or Vent.
The remaining space surrounding a chimney
liner, gas vent, special gas vent, or plastic piping
installed within a masonry chimney flue shall
not be used to vent another appliance.
Exception: The insertion of another liner or
vent within the chimney as provided in this
code and the liner or vent manufacturer's
instructions.
The remaining space surounding a chimney
liner, gas vent, special gas vent, or plastic piping
installed within a masonry, metal or factorybuilt chimney flue shall not be used to supply
combustion air.
Exception: Direct vent gas-fired appliances
designed for installation in a solid-fuelburning fireplace where installed in
accordance with the listing and the
manufacturer’s instruction. [NFPA 54:10.5]
802.6 Gas Vents.
802.6.1 A gas vent passing through a roof shall
extend through the entire roof flashing, roof
jack, or roof thimble and be terminated with a
listed termination cap.
802.6.1.1 Type B or Type L vents shall
extend in a generally vertical direction with
offsets not exceeding 45 degrees, except that
a vent system having not more than one 60
degree offset shall be permitted. Any angle
greater than 45 degrees from the vertical is
considered horizontal. The total horizontal
distance of a vent plus the horizontal vent
connector serving draft hood equipped
appliances shall not be greater than 75
percent of the vertical height of the vent.
115
802.6
Exception: Systems designed and sized as
provided in Section 803.0 or in accordance
with other approved engineering methods.
Vents serving Category I fan-assisted
appliances shall be installed in accordance
with the appliance manufacturer's instructions and Section 803.0 or other approved
engineering methods.
802.6.2 A gas vent shall terminate in accordance
with one of the following:
(1) Above the roof surface with a listed cap
or listed roof assembly. Gas vents
twelve (12) inches (300 mm) in size or
smaller with listed caps shall be permitted
to be terminated in accordance with
Figure 8-2, provided they are at least
eight (8) feet (2.4 m) from a vertical wall
or similar obstruction. All other gas
vents shall terminate not less than two
(2) feet (0.6 m) above the highest point
where they pass through the roof and at
least two (2) feet (0.6 m) higher than any
portion of a building within ten (10) feet
(3.1 m).
(2) Industrial gas utilization equipment as
provided in Section 802.2.4.
2007 CALIFORNIA MECHANICAL CODE
(3) Direct-vent systems as provided in
Section 802.2.5.
(4) Equipment with integral vents as
provided in Section 802.2.6.
(5) Mechanical draft systems as provided in
Section 802.3.4.
(6) Ventilating hoods and exhaust systems
as provided in Section 802.3.5.
802.6.2.1 A Type B or a Type L gas vent
shall terminate at least five (5) feet (1.5 m) in
vertical height above the highest connected
equipment draft hood or flue collar.
802.6.2.2 A Type BW gas vent shall
terminate at least twelve (12) feet (3.7 m) in
vertical height above the bottom of the wall
furnace.
802.6.2.3 A gas vent extending through an
exterior wall shall not terminate adjacent to
the wall or below eaves or parapets, except
as provided in Sections 802.2.5 and 802.3.4.
802.6.2.4 Decorative shrouds shall not be
installed at the termination of gas vents
except where such shrouds are listed for use
with the specific gas venting system and are
installed in accordance with manufacturers'
installation instructions.
802.6.2.5 All gas vents shall extend through
the roof flashing, roof jack, or roof thimble
and terminate with a listed cap or listed roof
assembly. [NFPA 54:12.7.2 (6)]
802.6.2.6 A gas vent shall terminate at least
three (3) feet (0.9 m) above a forced air inlet
located within ten (10) feet (3.0 m). [NFPA
54:12.7.2 (7)]
802.6.3 Size of Gas Vents. Venting systems
shall be sized and constructed in accordance
with Section 803.0 or other approved engineering
methods and the gas vent and gas equipment
manufacturers' instructions.
802.6.3.1 Category I Appliances. The sizing
of natural draft venting systems serving one
or more listed appliances equipped with a
draft hood or appliances listed for use with
Type B gas vent, installed in a single story of
a building, shall be in accordance with one of
the following methods.
FIGURE 8-2 Gas Vent Termination Locations for
Listed Caps 12 in. (300 mm) or Less in Size at
Least 8 ft. (2.4 m) from a Vertical Wall. [NFPA 54:
Figure 10.6.2]
116
(1) The provisions of Section 803.0.
(2) Vents serving fan-assisted combustion
system appliances, or combinations of
fan-assisted combustion system and
draft hood-equipped appliances shall be
CHIMNEYS AND VENTS
sized in accordance with Section 803.0
or other approved engineering methods.
(3) For sizing an individual gas vent for a
single, draft hood-equipped appliance,
the effective area of the vent connector
and the gas vent shall be not less than
the area of the appliance draft hood
outlet or greater than seven times the
draft hood outlet area.
(4) For sizing a gas vent connected to two
appliances, with draft hoods, the
effective area of the vent shall be not
less than the area of the larger draft
hood outlet plus 50 percent of the area
of the smaller draft hood outlet or
greater than seven times the smaller
draft hood outlet area.
(5) Approved engineering practices.
802.6.3.2 Category II, Category III, and
Category IV Appliances. The sizing of gas
vents for Category II, Category III, and
Category IV gas utilization equipment shall
be in accordance with the equipment
manufacturers' instructions.
802.6.3.3 Sizing. Chimney venting systems
using mechanical draft shall be sized in
accordance with approved engineering
methods.
802.6
802.6.4 Gas Vents Serving Equipment on
More Than One Floor. A common gas vent shall
be permitted in multistory installations to vent
Category I gas utilization equipment located on
more than one floor level, provided the venting
system is designed and installed in accordance
with approved engineering methods. For the
purpose of this section, crawl spaces, basements,
and attics shall be considered as floor levels.
All gas utilization equipment connected to
the common vent shall be located in rooms
separated from habitable space. Each of these
rooms shall have provisions for an adequate
supply of combustion, ventilation, and dilution
air that is not supplied from habitable space.
(See Figure 8-3.)
The size of the connectors and common
segments of multistory venting systems for gas
utilization equipment listed for use with Type B
double-wall gas vent shall be in accordance with
Table 8-10, provided:
(1) The available total height (H) for each
segment of a multistory venting system is
the vertical distance between the level of the
highest draft hood outlet or flue collar on
that floor and the centerline of the next
highest interconnection tee. (See Figure 8-4.)
(2) The size of the connector for a segment is
determined from its gas utilization
equipment heat input and available
connector rise, and shall not be smaller than
the draft hood outlet or flue collar size.
(3) The size of the common vertical vent
segment, and of the interconnection tee at
the base of that segment, shall be based on
the total gas utilization equipment heat
input entering that segment and its available
total height.
802.6.5 Support of Gas Vents. Gas vents shall
be supported and spaced in accordance with
their listings and the manufacturers' instructions.
FIGURE 8-3 Plan View of Practical Separation
Method for Multistory Gas Venting. [NFPA 54:
Figure 810.6.4]
802.6.6 Marking. In those localities where solid
and liquid fuels are used extensively, gas vents
shall be permanently identified by a label
attached to the wall or ceiling at a point where
the vent connector enters the gas vent. The label
shall read: "This gas vent is for appliances that
burn gas. Do not connect to solid or liquid-fuelburning appliances or incinerators." The
Authority Having Jurisdiction shall determine
whether its area constitutes such a locality.
[NFPA 54:10.6]
117
2007 CALIFORNIA MECHANICAL CODE
Table 8-2 – 802.7
Equipment
Listed equipment with
draft hoods and equipment listed for use with
Type B gas vents
TABLE 8-2
Clearance for Connectors
Minimum Distance from Combustible Material
Listed Type B
Gas Vent Material
As listed
Listed Type L
Vent Material
As listed
Single-Wall
Metal Pipe
6 in.
Factory-Built
Chimney Sections
As listed
Residential boilers and
furnaces with listed gas
conversion burner and
with draft hood
6 in.
6 in.
9 in.
As listed
Not permitted
As listed
9 in.
As listed
Residential incinerators
Not permitted
9 in.
18 in.
As listed
Unlisted residential
appliances with draft
hood
Not permitted
6 in.
9 in.
As listed
Residential appliances
listed for use with Type
L vents
Listed gas-fired toilets
Residential and low-heat
equipment other than
those above
Medium-heat equipment
Not permitted
As listed
As listed
As listed
Not permitted
9 in.
18 in.
As listed
Not permitted
Not permitted
36 in.
As listed
For SI units, 1 in.= 25.4 mm.
Note: These clearances shall apply unless the listing of an appliance or connector specifies clearances, in which case the listed
clearances shall apply. [NFPA 54: Table 10.7.4.4]
802.7 Single-Wall Metal Pipe.
802.7.1 Construction. Single-wall metal pipe
shall be constructed of galvanized sheet steel not
less than 0.0304 inch (0.7 mm) thick or of other
approved, noncombustible, corrosion-resistant
material.
802.7.2 Cold Climate. Uninsulated single-wall
metal pipe shall not be used outdoors in cold
climates for venting gas utilization equipment
in regions where the 99 percent winter design
temperature is below 32 degrees Fahrenheit.
[NFPA 54:12.8.2]
802.7.3 Termination. The termination of singlewall metal pipe shall comply with the following
requirements:
802.7.3.1 Single-wall metal pipe shall
terminate at least five (5) feet (1.5 m) in
vertical height above the highest connected
equipment draft hood outlet or flue collar.
802.7.3.2 Single-wall metal pipe shall
extend at least two (2) feet (0.6 m) above the
118
highest point where it passes through a roof
of a building and at least two (2) feet (0.6 m)
higher than any portion of a building within
a horizontal distance of ten (10) feet (3.1 m).
(See Figure 8-1.)
802.7.3.3 An approved cap or roof assembly
shall be attached to the terminus of a singlewall metal pipe. (Also see Section 802.7.4.3.)
802.7.4 Installation with Equipment Permitted
by Section 802.4.1.
802.7.4.1 Single-wall metal pipe shall be
used only for runs directly from the space
in which the gas utilization equipment is
located through the roof or exterior wall to
the outer air. A pipe passing through a
roof shall extend without interruption
through the roof flashing, roof jacket, or
roof thimble.
802.7.4.2 Single-wall metal pipe shall not
originate in any unoccupied attic or
concealed space and shall not pass through
CHIMNEYS AND VENTS
any attic, inside wall, concealed space, or
floor. For the installation of a single-wall
metal pipe through an exterior combustible
wall see Section 802.10.14.2.
802.7.4.3 Single-wall metal pipe used for
venting an incinerator shall be exposed and
readily examinable for its full length and
shall have suitable clearances maintained.
802.7.4.4 Minimum clearances from singlewall metal pipe to combustible material
shall be in accordance with Table 8-2.
Reduced clearances from single-wall metal
pipe to combustible material shall be as
specified for vent connectors in Table 5-3.
802.7.4.5 Where a single-wall metal pipe
passes through a roof constructed of
combustible material, a noncombustible,
nonventilating thimble shall be used at the
point of passage. The thimble shall extend at
least eighteen (18) inches (460 mm) above and
six (6) inches (150 mm) below the roof, with
the annular space open at the bottom and
closed only at the top. The thimble shall be
sized in accordance with Section 802.10.14.2.
802.7.5 Size of Single-Wall Metal Pipe. Singlewall metal piping shall comply with the
following requirements:
802.7.5.1 A venting system of a single-wall
metal pipe shall be sized in accordance with
one of the following methods and the gas
equipment manufacturer's instructions:
(1) For a draft hood–equipped appliance, in
accordance with Section 803.0.
(2) For a venting system for a single
appliance with a draft hood, the areas of
the connector and the pipe each shall
not be less than the area of the appliance
flue collar or draft hood outlet, whichever
is smaller. The vent area shall not be
greater than seven times the draft hood
outlet area.
(3) Other approved engineering methods.
802.7.5.2 Where a single-wall metal pipe is
used and has a shape other than round, it shall
have an equivalent effective area equal to the
effective area of the round pipe for which it is
substituted, and the minimum internal
dimension of the pipe shall be two (2) inches
(50 mm).
802.7.5.3 The vent cap or a roof assembly
shall have a venting capacity not less than
that of the pipe to which it is attached.
802.7 – 802.9
802.7.6 Support of Single-Wall Metal Pipe. All
portions of single-wall metal pipe shall be
supported for the design and weight of the
material employed.
802.7.7 Marking. Single-wall metal pipe shall
comply with the marking provisions of Section
802.6.6. [NFPA 54:10.7]
802.8 Through-the-Wall Vent Termination.
802.8.1 A mechanical draft venting system shall
terminate at least three (3) feet (0.9 m) above any
forced air inlet located within ten (10) feet (3.1 m).
Exception 1: This provision shall not apply
to the combustion-air intake of a direct-vent
appliance.
Exception 2: This provision shall not apply
to the separation of the integral outdoor-air
inlet and flue gas discharge of listed outdoor
appliances.
802.8.2 A mechanical draft venting system of
other than direct-vent type shall terminate at
least four (4) feet (1.2 m) below, four (4) feet (1.2
m) horizontally from, or one (1) feet (300 mm)
above any door, operable window, or gravity air
inlet into any building. The bottom of the vent
terminal shall be located at least twelve (12)
inches (300 mm) above grade.
802.8.3 The vent terminal of a direct-vent
appliance with an input of 10,000 Btu/h (3 kW)
or less shall be located at least six (6) inches (150
mm) from any air opening into a building, and
such an appliance with an input over 10,000
Btu/h (3 kW) but not over 50,000 Btu/h (14.7
kW) shall be installed with a nine (9) inches (230
mm) vent termination clearance, and an
appliance with an input over 50,000 Btu/h (14.7
kW) shall have at least a twelve (12) inches (300
mm) vent termination clearance. The bottom of
the vent terminal and the air intake shall be
located at least twelve (12) inches (300 mm)
above grade.
802.8.4 Through-the-wall vents for Category II
and Category IV appliances and noncategorized
condensing appliances shall not terminate over
public walkways or over an area where
condensate or vapor could create a nuisance or
hazard or could be detrimental to the operation
of regulators, relief valves, or other equipment.
Where local experience indicates that
condensate is a problem with Category I and
Category III appliances, this provision shall
also apply. [NFPA 54:10.8]
802.9 Condensation Drain.
802.9.1 Provision shall be made to collect and
119
802.9 – 802.10
dispose of condensate from venting systems
serving Category II and Category IV gas
utilization equipment and noncategorized
condensing appliances in accordance with
Section 802.8.4.
802.9.2 Where local experience indicates that
condensation is a problem, provision shall be
made to drain off and dispose of condensate
from venting systems serving Category I and
Category III gas utilization equipment in
accordance with Section 802.8.4. [NFPA 54:10.9]
802.10 Vent Connectors for Category I Gas
Utilization Equipment.
802.10.1 Where Required. A vent connector
shall be used to connect gas utilization
equipment to a gas vent, chimney, or singlewall metal pipe, except where the gas vent,
chimney, or single-wall metal pipe is directly
connected to the equipment.
802.10.2 Materials.
802.10.2.1 A vent connector shall be made
of noncombustible, corrosion-resistant
material capable of withstanding the vent
gas temperature produced by the gas
utilization equipment and of sufficient
thickness to withstand physical damage.
802.10.2.2 Where the vent connector used for
gas utilization equipment having a draft hood
or a Category I appliance is located in or
passes through an unconditioned area, that
portion of the vent connector shall be listed
Type B, listed Type L, or listed vent material
having equivalent insulation qualities.
Exception: Single-wall metal pipe
located within the exterior walls of the
building and located in areas having a
local 99 percent winter design temperature
of 5˚ F or higher.
802.10.2.3 Where the vent connector used
for gas utilization equipment having a draft
hood or a Category I appliance is located in
or passes through attics and crawl spaces, that
portion of the vent connector shall be listed
Type B, listed Type L, or listed vent material
having equivalent insulation qualities.
802.10.2.4 Vent connectors for residentialtype appliances shall comply with the
following:
(1) Vent connectors for listed gas
appliances having draft hoods and for
appliances having draft hoods and
equipped with listed conversion
burners that are not installed in attics,
120
2007 CALIFORNIA MECHANICAL CODE
crawl spaces, or other unconditioned
areas shall be one of the following:
(a) Type B or Type L vent material.
(b) Galvanized sheet steel not less than
0.018 in. (0.46 mm) thick.
(c) Aluminum (1100 or 3003 alloy or
equivalent) sheet not less than 0.027
in. (0.69 mm) thick.
(d) Stainless steel sheet not less than
0.012 in. (0.31 mm) thick.
(e) Smooth-interior-wall metal pipe
having resistance to heat and
corrosion equal to or greater than
that of b, c, or d above.
(f) A listed vent connector.
(2) Vent connectors shall not be covered
with insulation.
Exception: Listed insulated vent
connectors shall be installed according to the terms of their listing.
802.10.2.5 A vent connector for
nonresidential low-heat equipment shall be
a factory-built chimney section or steel pipe
having resistance to heat and corrosion
equivalent to that for the appropriate
galvanized pipe as specified in Table 8-3.
Factory-built chimney sections shall be
joined together in accordance with the
chimney manufacturer's instructions.
[NFPA 54: 12.11.2.5]
802.10.2.6 Vent connectors for mediumheat equipment and commercial and
industrial incinerators shall be constructed
of factory-built, medium-heat chimney
sections or steel of a thickness not less than
that specified in Table 8-4, and shall comply
with the following:
(1) A steel vent connector for equipment
with a vent gas temperature in excess of
1000°F (538°C) measured at the entrance
to the connector shall be lined with
medium-duty fire brick (ASTM C 64,
Specification for Refractories for
Incinerators and Boilers, Type F) or the
equivalent.
(2) The lining shall be at least 2-1/2 inches (64
mm) thick for a vent connector having a
diameter or greatest cross-sectional
dimension of eighteen (18) inches (460 mm)
or less.
(3) The lining shall be at least 4-1/2 inches
(110 mm) thick laid on the 4-1/2 inches (110
mm) bed for a vent connector having
CHIMNEYS AND VENTS
diameter or greatest cross-sectional
dimension greater than eighteen (18)
inches (460 mm).
(4) Factory-built chimney sections, if
employed, shall be joined together in
accordance with the chimney manufacturer's instructions.
TABLE 8-3
Minimum Thickness for Galvanized Steel Vent
Connectors for Low-Heat Appliances
Diameter of Connector (in.)
Minimum Thickness (in.)
Less than 6
0.019
6 to less than 10
0.023
10 to 12 inclusive
0.029
14 to 16 inclusive
0.034
Over 16
0.056
For SI units, 1 in. = 25.4 mm; 1 in.2 = 645 mm2.
[NFPA 54: Table 10.10.2.5]
TABLE 8-4
Minimum Thickness for Steel Vent Connectors
for Medium-Heat Equipment and Commercial and
Industrial Incinerators
Vent Connector Size
Diameter (in.)
Up to 14
Over 14 to 16
Over 16 to 18
Over 18
Minimum
Area (in. )
Thickness (in.)
154 to 201
0.067
2
Up to 154
201 to 254
Larger than 254
0.053
0.093
0.123
For SI units, 1 in. = 25.4 mm; 1 in.2 = 645 mm2.
[NFPA 54: Table 10.10.2.6]
802.10.3 Size of Vent Connector.
802.10.3.1 A vent connector for gas
utilization equipment with a single draft hood
or for a Category I fan-assisted combustion
system appliance shall be sized and installed
in accordance with Section 803.0 or other
approved engineering methods.
802.10.3.2 For a single appliance having more
than one draft hood outlet or flue collar, the
manifold shall be constructed according to the
instructions of the appliance manufacturer.
Where there are no instructions, the manifold
802.10
shall be designed and constructed in
accordance with approved engineering
practices. As an alternate method, the effective
area of the manifold shall equal the combined
area of the flue collars or draft hood outlets
and the vent connectors shall have a
minimum one (1) foot (0.3 m) rise.
802.10.3.3 Where two or more gas appliances
are connected to a common vent or chimney,
each vent connector shall be sized in
accordance with Section 803.0 or other
approved engineering methods. As an
alternative method applicable only when all of
the appliances are draft hood equipped, each
vent connector shall have an effective area not
less than the area of the draft hood outlet of
the appliance to which it is connected.
802.10.3.4 Where two or more gas appliances
are vented through a common vent connector
or vent manifold, the common vent connector
or vent manifold shall be located at the
highest level consistent with available headroom and clearance to combustible material
and shall be sized in accordance with Section
803.0 or other approved engineering methods.
As an alternate method applicable only
where there are two draft hood–equipped
appliances, the effective area of the common
vent connector or vent manifold and all
junction fittings shall be not less than the area
of the larger vent connector plus 50 percent
of the areas of smaller flue collar outlets.
802.10.3.5 Where the size of a vent connector
is increased to overcome installation limitations and obtain connector capacity equal to
the equipment input, the size increase shall
be made at the equipment draft hood outlet.
802.10.4 Two or More Appliances Connected
to a Single Vent.
802.10.4.1 Where two or more vent connectors
enter a common gas vent, chimney flue, or
single-wall metal pipe, the smaller connector
shall enter at the highest level consistent
with the available headroom or clearance to
combustible material.
802.10.4.2 Vent connectors serving Category
I appliances shall not be connected to any
portion of a mechanical draft system
operating under positive static pressure,
such as those serving Category III or
Category IV appliances.
802.10.5 Clearance. Minimum clearances from
vent connectors to combustible material shall be
in accordance with Table 8-2.
121
802.10
Exception: The clearance between a vent
connector and combustible material shall
be permitted to be reduced where the
combustible material is protected as
specified for vent connectors in Table 5-3.
802.10.6 Avoid Unnecessary Bends. A vent
connector shall be installed so as to avoid turns
or other construction features that create
excessive resistance to flow of vent gases.
802.10.7 Joints. Joints between sections of
connector piping and connections to flue collars
or draft hood outlets shall be fastened in
accordance with one of the following methods:
(1) By sheet metal screws.
(2) Vent connectors of listed vent material shall
be assembled and connected to flue collars
or draft hood outlets in accordance with
the manufacturers' instructions.
(3) Other approved means.
802.10.8 Slope. A vent connector shall be
installed without any dips or sags and shall
slope upward toward the vent or chimney at
least 1/4 in./ft. (20 mm/m).
Exception: Vent connectors attached to a
mechanical draft system installed in accordance with the manufacturers' instructions.
802.10.9 Length of Vent Connector.
802.10.9.1 A vent connector shall be as
short as practical, and the gas utilization
equipment located as close as practical to
the chimney or vent.
802.10.9.2 The maximum horizontal length
of a single-wall connector shall be 75 percent
of the height of the chimney or vent except
for engineered systems. The maximum
length of an individual connector for a
chimney or vent system serving multiple
appliances, from the appliance outlet to the
junction with the common vent or another
connector, shall be 100 percent of the height
of the chimney or vent. [NFPA 54:12.11.9.2]
802.10.9.3 The maximum horizontal length
of a Type B double-wall connector shall be
100 percent of the height of the chimney or
vent, except for engineered systems. The
maximum length of an individuall connector
for a chimney or vent system serving multiple
appliances, from the appliance outlet to the
junction with the common vent or another
connector, shall be 100 percent of the height
of the chimney or vent. [NFPA 54: 12.11.9.3]
802.10.10 Support. A vent connector shall be
supported for the design and weight of the
122
2007 CALIFORNIA MECHANICAL CODE
material employed to maintain clearances and
prevent physical damage and separation of joints.
802.10.11 Chimney Connection. Where entering
a flue in a masonry or metal chimney, the vent
connector shall be installed above the extreme
bottom to avoid stoppage. Where a thimble or
slip joint is used to facilitate removal of the
connector, the connector shall be firmly attached
to or inserted into the thimble or slip joint to
prevent the connector from falling out. Means
shall be employed to prevent the connector from
entering so far as to restrict the space between its
end and the opposite wall of the chimney flue.
802.10.12 Inspection. The entire length of a
vent connector shall be readily accessible for
inspection, cleaning, and replacement.
802.10.13 Fireplaces. A vent connector shall
not be connected to a chimney flue serving a
fireplace unless the fireplace flue opening is
permanently sealed.
802.10.14 Passage Through Ceilings, Floors,
or Walls.
802.10.14.1 A vent connector shall not pass
through any ceiling, floor, or fire-resistance
rated wall. A single-wall metal pipe connector
shall not pass through any interior wall.
Exception: Vent connectors made of listed
Type B or Type L vent material and serving
listed equipment with draft hoods and other
equipment listed for use with Type B gas
vents that pass through walls or partitions
constructed of combustible material shall be
installed with not less than the listed
clearance to combustible material.
802.10.14.2 A vent connector made of a
single-wall metal pipe shall not pass
through a combustible exterior wall unless
guarded at the point of passage by a
ventilated metal thimble not smaller than
the following:
(1) For listed appliances equipped with
draft hoods and appliances listed for use
with Type B gas vents, the thimble shall
be a minimum of four (4) inches (100 mm)
larger in diameter than the vent connector.
Where there is a run of not less than six
(6) feet (1.8 m) of vent connector in the
opening between the draft hood outlet
and the thimble, the thimble shall be a
minimum of two (2) inches (50 mm)
larger in diameter than the vent connector.
CHIMNEYS AND VENTS
(2) For unlisted appliances having draft
hoods, the thimble shall be a minimum
of six (6) inches (150 mm) larger in
diameter than the vent connector.
(3) For residential and low-heat appliances,
the thimble shall be a minimum of
twelve (12) inches (300 mm) larger in
diameter than the vent connector.
Exception: In lieu of thimble protection, all combustible material in the
wall shall be removed from the vent
connector a sufficient distance to
provide the specified clearance
from such vent connector to
combustible material. Any material
used to close up such opening shall
be noncombustible.
802.10.14.3 Vent connectors for mediumheat equipment shall not pass through walls
or partitions constructed of combustible
material. [NFPA 54:10.10.14.3]
802.11 Vent Connectors for Category II, Category
III, and Category IV Gas Utilization Equipment.
(See Section 802.4.) [NFPA 54:10.11]
802.12 Draft Hoods and Draft Controls.
802.12.1 Equipment Requiring Draft Hoods.
Vented gas utilization equipment shall be
installed with draft hoods.
Exception: Dual oven–type combination
ranges; incinerators; direct-vent equipment;
fan-assisted combustion system appliances;
equipment requiring chimney draft for
operation; single-firebox boilers equipped with
conversion burners with inputs greater than
400,000 Btu/h (117 kW); equipment equipped
with blast, power, or pressure burners that are
not listed for use with draft hoods; and
equipment designed for forced venting.
802.12.2 Installation. A draft hood supplied
with or forming a part of listed vented gas
utilization equipment shall be installed without
alteration, exactly as furnished and specified by
the equipment manufacturer. If a draft hood is
not supplied by the equipment manufacturer
where one is required, a draft hood shall be
installed, be of a listed or approved type, and, in
the absence of other instructions, be of the same
size as the equipment flue collar. Where a draft
hood is required with a conversion burner, it
shall be of a listed or approved type. Where it is
determined that a draft hood of special design is
needed or preferable for a particular installation,
the installation shall be in accordance with the
recommendations of the equipment manufac-
802.10 – 802.15
turer and shall be with the approval of the
Authority Having Jurisdiction.
802.12.3 Draft Control Devices. Where a draft
control device is part of the gas utilization
equipment or is supplied by the equipment
manufacturer, it shall be installed in accordance
with the manufacturer's instructions. In the
absence of manufacturer's instructions, the device
shall be attached to the flue collar of the equipment
or as near to the equipment as practical.
802.12.4 Additional Devices. Gas utilization
equipment (except incinerators) requiring
controlled chimney draft shall be permitted to be
equipped with a listed double-acting barometric
draft regulator installed and adjusted in
accordance with the manufacturers' instructions.
802.12.5 Location. Draft hoods and barometric
draft regulators shall be installed in the same
room or enclosure as the equipment in such a
manner as to prevent any difference in pressure
between the hood or regulator and the
combustion air supply.
802.12.6 Positioning. Draft hoods and draft
regulators shall be installed in the position for
that they were designed with reference to the
horizontal and vertical planes and shall be
located so that the relief opening is not
obstructed by any part of the equipment or
adjacent construction. The equipment and its
draft hood shall be located so that the relief
opening is accessible for checking vent operation.
802.12.7 Clearance. A draft hood shall be
located so that its relief opening is not less than
six (6) inches (150 mm) from any surface except
that of the equipment it serves and the venting
system to which the draft hood is connected.
Where a greater or lesser clearance is indicated
on the equipment label, the clearance shall not
be less than that specified on the label. Such
clearances shall not be reduced. [NFPA 54:10.12]
802.13 Manually Operated Dampers. A manually
operated damper shall not be placed in any equipment
vent connector. Fixed baffles shall not be classified as
manually operated dampers. [NFPA 54:10.13]
802.14 Automatically Operated Vent Dampers. An
automatically operated vent damper shall be of a listed
type. [NFPA 54:10.14]
802.15 Obstructions. Devices that retard the flow of
vent gases shall not be installed in a vent connector,
chimney, or vent. The following shall not be
considered as obstructions:
(1) Draft regulators and safety controls
specifically listed for installation in venting
123
802.15 – 803.1
systems and installed in accordance with the
terms of their listing.
(2) Approved draft regulators and safety
controls designed and installed in accordance
with approved engineering methods.
(3) Listed heat reclaimers and automatically
operated vent dampers installed in accordance with the terms of their listing.
(4) Vent dampers serving listed appliances
installed in accordance with Sections 803.1
and 803.2.1 or other approved engineering
methods.
(5) Approved economizers, heat reclaimers,
and recuperators installed in venting
systems of equipment not required to be
equipped with draft hoods, provided the
gas utilization equipment manufacturer's
instructions cover the installation of such a
device in the venting system and performance
in accordance with Sections 802.3.1 and
802.3.2 is obtained. [NFPA 54:10.15]
803.0 Sizing of Category I Venting Systems
803.1 These venting tables shall not be used where
obstructions (see Section 802.15) are installed in the
venting system. The installation of vents serving
listed appliances with vent dampers shall be in
accordance with the appliance manufacturer’s
instructions or in accordance with the following:
(1) The maximum capacity of the vent system
shall be determined using the NAT Max
column.
(2) The minimum capacity shall be determined
as if the appliance were a fan-assisted
appliance, using the FAN Min column to
determine the minimum capacity of the
vent system. Where the corresponding
FAN Min is NA, the vent configuration shall
not be permitted and an alternative
venting configuration shall be utilized.
803.1.1 Where the vent size determined from
the tables is smaller than the appliance draft
hood outlet or flue collar, the use of the
smaller size shall be permitted provided that
t h e i n s tallation complies with all of the
following requirements:
(1) The total vent height (H) is at least ten (10)
feet (3 m).
(2) Vents for appliance draft hood outlets or flue
collars twelve (12) inches (300 mm) in
diameter or smaller are not reduced more
than one table size.
124
2007 CALIFORNIA MECHANICAL CODE
(3) Vents for appliance draft hood outlets or
flue collars larger than twelve (12) inches
(300 mm) in diameter are not reduced more
than two table sizes.
(4) The maximum capacity listed in the tables
for a fan-assisted appliance is reduced by
ten (10) percent (0.90 maximum table capacity).
(5) The draft hood outlet is greater than four (4)
inches (100 mm) in diameter. Do not connect
a three (3) inches (80 mm) diameter vent to a
four (4) inches (100 mm) diameter draft
hood outlet. This provision shall not apply
to fan-assisted appliances.
803.1.2 Single-appliance venting configurations
with zero (0) lateral lengths in Tables 8-5, 8-6,
and 8-9 shall not have elbows in the venting
system. For vent configurations with lateral
lengths, the venting tables include allowance for
two 90 degree turns. For each additional elbow
up to and including 45 degrees, the maximum
capacity listed in the venting tables shall be
reduced by 5 percent. For each elbow greater
than 45 degrees up to and including 90 degrees,
the maximum capacity listed in the venting
tables shall be reduced by 10 percent.
803.1.3 Zero (0) lateral (L) shall apply only to a
straight vertical vent attached to a top-outlet
draft hood or flue collar.
803.1.4 Sea level input ratings shall be used
when determining maximum capacity for highaltitude installation. Actual input (derated for
altitude) shall be used for determining minimum
capacity for high-altitude installation.
803.1.5 For appliances with more than one input
rate, the minimum vent capacity (FAN Min)
determined from the tables shall be less than the
lowest appliance input rating, and the maximum
vent capacity (FAN Max/NAT Max) determined
from the tables shall be greater than the highest
appliance rating input.
803.1.6 Listed corrugated metallic chimney liner
systems in masonry chimneys shall be sized by
using Table 8-5 or 8-6 for Type B vents, with the
maximum capacity reduced by 20 percent (0.80
maximum capacity) and the minimum capacity
as shown in Table 8-5 or 8-6. Corrugated metallic
liner systems installed with bends or offsets shall
have their maximum capacity further reduced in
accordance with Section 803.1.2. The 20 percent
reduction for corrugated metallic chimney liner
systems includes an allowance for one long
radius 90 degree turn at the bottom of the liner.
803.1.7 Where the vertical vent has a larger
diameter than the vent connector, the vertical
CHIMNEYS AND VENTS
vent diameter shall be used to determine the
minimum vent capacity, and the connector
diameter shall be used to determine the
maximum vent capacity. The flow area of the
vertical vent shall not exceed seven times the
flow area of the listed appliance categorized vent
area, flue collar area, or draft hood outlet area
unless designed in accordance with approved
engineering methods.
803.1.8 Connection to Chimney Liners.
Connections between chimney liners and listed
double-wall connectors shall be made with listed
adapters designed for such purpose. [NFPA
54:13.1.8]
803.1.8.1 Tables 8-5 through 8-9 shall be
used for chimneys and vents not exposed to
the outdoors below the roof line. A Type B
vent or listed chimney lining system passing
through an unused masonry chimney flue
shall not be considered to be exposed to the
outdoors. A Type B vent passing through an
unventilated enclosure or chase insulated to
a value of not less than R8 shall not be
considered to be exposed to the outdoors.
Table 8-7 in combination with Table 8-15
shall be used for clay-tile-lined exterior
masonry chimneys, provided all of the
following are met:
(1) The vent connector is Type B double wall.
(2) The vent connector length is limited to
1-1/2 feet for each inch (180 mm/mm) of
vent connector diameter.
(3) The appliance is draft hood equipped.
(4) The input rating is less than the maximum
capacity given in Table 8-7.
(5) For a water heater, the outdoor design
temperature shall not be less than 5°F
(–15°C).
(6) For a space-heating appliance, the input
rating is greater than the minimum
capacity given by Table 8-15.
(7) Where the conditions of 803.1.8.1(1)
through (6) cannot be met, an alternative
venting design shall be used, such as a
listed chimney lining system.
Exception: Vents serving listed appliances
installed in accordance with the appliance
manufacturer’s instructions and the
terms of the listing.
803.1.9 Corrugated vent connectors shall not be
smaller than the listed appliance categorized
vent diameter, flue collar diameter, or draft
hood outlet diameter.
803.1 – 803.2
803.1.9.1 Vertical Vent Upsizing/7 Times
Rule. Where the vertical vent has a larger
diameter than the vent connector, the
vertical vent diameter shall be used to
determine the minimum vent capacity, and
the connector diameter shall be used to
determine the maximum vent capacity. The
flow area of the vertical vent shall not exceed
seven times the flow area of the listed
appliance categorized vent area, flue collar
area, or draft hood outlet area unless
designed in accordance with approved
engineering methods. [NFPA 54: 13.1.9]
803.1.10 Vent connectors shall not be upsized
more than two sizes greater than the listed
appliance categorized vent diameter, flue collar
diameter, or draft hood outlet diameter.
803.1.11 In a single run of vent or vent connector, more than one diameter and type shall be
permitted to be used, provided that all the sizes
and types are permitted by the tables.
803.1.12 Interpolation shall be permitted in
calculating capacities for vent dimensions that
fall between table entries. (See Example 8-1 in
Section 803.2.23.)
803.1.13 Extrapolation beyond the table entries
shall not be permitted.
For SI units, 1 in. = 25.4 mm; 1 ft. = 0.305 m;
1,000 Btu/h = 0.293 kW; 1 in.2 = 645 mm2.
803.1.14 For vent heights lower than six (6) feet
and higher than shown in the tables, engineering
methods shall be used to calculate vent capacities.
[NFPA 54:13.1]
803.1.15 Draft Hood Conversion Accessories.
Draft hood conversion accessories for use with
masonry chimneys venting listed Category I fanassisted appliances shall be listed and installed in
accordance with the listed accessory manufacturers’ installation instructions. [NFPA 54:13.1.10]
803.2 Additional Requirements to Multiple
Appliance Vent Tables 8-10 through 8-14 and
Tables 8-16 through 8-19.
803.2.1 These venting tables shall not be used
where obstructions (see Section 802.15) are
installed in the venting system. The installation
of vents serving listed appliances with vent
dampers shall be in accordance with the
appliance manufacturer’s instructions or in
accordance with the following:
(1) The maximum capacity of the vent
connector shall be determined using the
NAT Max column.
125
803.2 – Figure 8-4
(2) The maximum capacity of the vertical vent
or chimney shall be determined using the
FAN+NAT column when the second
appliance is a fan-assisted appliance, or the
NAT+NAT column when the second
appliance is equipped with a draft hood.
2007 CALIFORNIA MECHANICAL CODE
(3) The minimum capacity shall be determined
as if the appliance were a fan-assisted
appliance.
(a) The minimum capacity of the vent
connector shall be determined using the
FAN Min column.
(b) The FAN+FAN column shall be used
when the second appliance is a fanassisted appliance, and the FAN+NAT
column shall be used when the second
appliance is equipped with a draft
hood, to determine whether the vertical
vent or chimney configuration is not
permitted (NA). Where the vent
configuration is NA, the vent configuration shall not be permitted,
and an alternative venting configuration
shall be utilized.
803.2.2 The maximum vent connector horizontal
length shall be 18 in./in. (180 mm/mm) of
connector diameter as follows:
Connector
Diameter Maximum
(in.)
Connector Horizontal
Length
(ft.)
3
4-1/2
5
7-1/2
7
10-1/2
9
13-1/2
12
18
4
6
8
10
14
16
18
20
22
24
6
9
12
15
21
24
27
30
33
36
For SI units, 1 in. = 25.4 mm; 1 ft. = 0.305 m.
126
FIGURE 8-4 Use of Manifolded Common Vent
Connector.
803.2.3 The vent connector shall be routed to the
vent utilizing the shortest possible route.
Connectors with longer horizontal lengths than
those listed in Section 803.2.2 are permitted
under the following conditions:
(A) The maximum capacity (FAN Max or NAT
Max) of the vent connector shall be reduced
10 percent for each additional multiple of
the length listed in 803.2.2. For example, the
maximum length listed for a four (4) inches
(100 mm) connector is six (6) feet (1.8 m).
With a connector length greater than six (6)
feet (1.8 m) but not exceeding twelve (12)
feet (3.7 m), the maximum capacity must be
reduced by ten (10) percent (0.90 maximum
vent connector capacity). With connector
length greater than twelve (12) feet (3.7 m)
but not exceeding eighteen (18) feet (5.5 m),
the maximum capacity must be reduced by
20 percent (0.80 maximum vent capacity).
(B) For a connector serving a fan-assisted
appliance, the minimum capacity (FAN
Min) of the connector shall be determined
by referring to the corresponding singleappliance table. For Type B double-wall
connectors, Table 8-5 shall be used. For
single-wall connectors, Table 8-6 shall be
used. The height (H) and lateral (L) shall be
measured according to the procedures for a
single-appliance vent, as if the other
appliances were not present.
CHIMNEYS AND VENTS
Figure 8-5 – 803.2
803.2.6 For each elbow up to and including 45
degrees in the common vent, the maximum
common vent capacity listed in the venting
tables shall be reduced by 5 percent. For each
elbow greater than 45 degrees up to and
including 90 degrees, the maximum common
vent capacity listed in the venting tables shall be
reduced by 10 percent.
803.2.7 The vent connector capacities listed in
the common vent sizing tables include
allowance for two 90 degree elbows. For each
additional elbow up to and including 45
degrees, the maximum vent connector capacity
listed in the venting tables shall be reduced by 5
percent. For each elbow greater than 45 degrees
up to and including 90 degrees, the maximum
vent connector capacity listed in the venting
tables shall be reduced by 10 percent.
803.2.8 Common Vent Minimum Size. The
cross-sectional area of the common vent shall be
equal to or greater than the cross-sectional area
of the largest connector. [NFPA 54: 13.2.8]
803.2.9 Tee and Wye Fittings. Tee and wye
fittings connected to a common vent shall be
considered as part of the common vent and
constructed of materials consistent with that of
the common vent. [NFPA 54:13.2.9]
FIGURE 8-5 Multistory Gas Vent Design
Procedure for Each Segment of System.
803.2.4 Where the vent connectors are combined
prior to entering the vertical portion of the
common vent to form a common vent manifold,
the size of the common vent manifold and the
common vent shall be determined by applying a
10 percent reduction (0.90 x maximum common
vent capacity) to the Common Vent Capacity part
of the common vent tables. The length of the
common vent connector manifold (LM) shall not
exceed 18 in./in. (180 mm/mm) of common vent
connector manifold diameter (D). (See Figure 8-4.)
803.2.5 Where the common vertical vent is
offset, the maximum capacity of the common
vent shall be reduced in accordance with Section
803.2.6, and the horizontal length of the common
vent offset shall not exceed 18 in./in. (180
mm/mm) of common vent diameter.
803.2.9.1 At the point where tee or wye
fittings connect to a common vent, the
opening size of the fitting shall be equal to
the size of the common vent. Such fittings
shall not be prohibited from having reduced
size openings at the point of connection of
appliance vent connectors.
803.2.10 Sea level input ratings shall be used
when determining maximum capacity for highaltitude installation. Actual input (derated for
altitude) shall be used for determining minimum
capacity for high-altitude installation.
803.2.11 The connector rise (R) for each appliance
connector shall be measured from the draft hood
outlet or flue collar to the centerline where the
vent gas streams come together.
803.2.12 For multiple units of gas utilization
equipment all located on one floor, available
total height (H) shall be measured from the
highest draft hood outlet or flue collar up to the
level of the outlet of the common vent.
803.2.13 For multistory installations, available
total height (H) for each segment of the system
shall be the vertical distance between the highest
draft hood outlet or flue collar entering that
segment and the centerline of the next higher
interconnection tee. (See Figure 8-5.)
127
803.2 – Figure 8-6
803.2.14 The size of the lowest connector and of
the vertical vent leading to the lowest
interconnection of a multistory system shall be
in accordance with Table 8-5 or 8-6 for available
total height (H) up to the lowest interconnection.
(See Figure 8-6.)
2007 CALIFORNIA MECHANICAL CODE
803.2.15 Where used in multistory systems,
vertical common vents shall be Type B doublewall and shall be installed with a listed vent cap.
803.2.20 Tables 8-10 and 8-11 shall be used for
chimneys and vents not exposed to the outdoors
below the roof line. A Type B vent passing
through an unventilated enclosure or chase
insulated to a value of not less than R8 shall not
be considered to be exposed to the outdoors.
Tables 8-16 through 8-19 shall be used for claytile-lined exterior masonry chimneys, provided
all of the following conditions are met:
(1) The offset angle shall not exceed 45 degrees
from vertical.
(3) The combined appliance input rating is less
than the maximum capacity given by Table
8-16 (for NAT+NAT) or Table 8-18 (for
FAN+NAT).
803.2.16 Offsets in multistory common vent
systems shall be limited to a single offset in each
system, and systems with an offset shall comply
with all of the following:
(2) The horizontal length of the offset shall not
exceed eighteen (18) inches for each inch (180
mm/mm) of common vent diameter of the
segment in that the offset is located.
(3) For the segment of the common vertical vent
containing the offset, the common vent
capacity listed in the common venting tables
shall be reduced by 20 percent (0.80 x
maximum common vent capacity).
(1) Vent connector is Type B double-wall.
(2) At least one appliance is draft hood-equipped.
(4) The input rating of each space-heating
appliance is greater than the minimum
input rating given by Table 8-17 (for
NAT+NAT) or Table 8-19 (for FAN+NAT).
(4) A multistory common vent shall not be
reduced in size above the offset.
803.2.17 Where two or more appliances are
connected to a vertical vent or chimney, the flow
area of the largest section of vertical vent or
chimney shall not exceed seven times the smallest
listed appliance categorized vent areas, flue collar
area, or draft hood outlet area, unless designed in
accordance with approved engineering methods.
803.2.18 For appliances with more than one
input rate, the minimum vent connector capacity
(FAN Min) determined from the tables shall be
less than the lowest appliance input rating, and
the maximum vent connector capacity (FAN Max
or NAT Max) determined from the tables shall be
greater than the highest appliance input rating.
803.2.19 Listed, corrugated metallic chimney
liner systems in masonry chimneys shall be
sized by using Table 8-10 or 8-11 for Type B
vents, with the maximum capacity reduced by
20 percent (0.80 maximum capacity) and the
minimum capacity as shown in Table 8-10 or 8-11.
Corrugated metallic liner systems installed with
bends or offsets shall have their maximum
capacity further reduced in accordance with
Sections 803.2.5 and 803.2.6. The 20 percent
reduction for corrugated metallic chimney liner
systems includes an allowance for one long
radius 90 degree turn at the bottom of the liner.
128
FIGURE 8-6 Principle of Design of Multistory
Vents Using Vent Connector and Common Vent
Design Tables.
CHIMNEYS AND VENTS
(5) The vent connector sizing is in accordance
with Table 8-12.
(6) Where these conditions cannot be met, an
alternative venting design shall be used,
such as a listed chimney lining system.
Exception: Vents serving listed appliances
installed in accordance with the appliance
manufacturer's installation instructions.
803.2.21 Vent connectors shall not be increased
more than two sizes greater than the listed
appliance categorized vent diameter, flue collar
diameter, or draft hood outlet diameter. Vent
connectors for draft hood-equipped appliances
shall not be smaller than the draft hood outlet
diameter. Where a vent connector size(s)
determined from the tables for a fan-assisted
appliance(s) is smaller than the flue collar
diameter, the use of the smaller size(s) shall be
permitted provided that the installation
complies with all of the following:
(1) Vent connectors for fan-assisted appliance
flue collars twelve (12) inches (300 mm) in
diameter or smaller are not reduced by more
than one table size [e.g., 12 in. to 10 in. (300
mm to 250 mm) is a one-size reduction] and
those larger than twelve (12) inches (300 mm)
in diameter are not reduced more than two
table sizes [e.g., 24 in. to 20 in. (610 mm to 510
mm) is a two-size reduction].
(2) The fan-assisted appliance(s) is common
vented with a draft hood equipped appliance(s).
(3) The vent connector has a smooth interior
wall.
803.2.22 All combinations of pipe sizes and
single-wall and double-wall metal pipe shall be
allowed within any connector run(s) or within
the common vent provided ALL of the
appropriate tables permit ALL of the desired
sizes and types of pipe, as if they were used for
the entire length of the subject connector or vent.
Where single-wall and Type B double-wall metal
pipes are used for vent connectors within the
same venting system, the common vent must be
sized using Table 8-11 or 8-13, as appropriate.
803.2
Values. An installer has an 80,000 Btu/h. input
appliance with a four (4) inches diameter draft
hood outlet that needs to be vented into a twelve
(12) foot high Type B vent. The vent connector
has a five (5) foot lateral length and is also Type
B. Can this appliance be vented using a four (4)
inch diameter vent?
Solution
Table 8-5 is used in the case of an all Type B
vent system. However, since there is no entry
in Table 8-5 for a height of 12 ft., interpolation
must be used. Read down the 4 in. diameter
NAT Max column to the row associated with
10 ft. height and 5 ft. lateral to find the capacity
value of 77,000 Btu/h. Read further down to
the 15 ft. height, 5 ft. lateral row to find the
capacity value of 87,000 Btu/h. The difference
between the 15 ft. height capacity value and
the 10 ft. height capacity value is 10,000 Btu/h.
The capacity for a vent system with a 12 ft.
height is equal to the capacity for a 10 ft. height
plus 2/5 of the difference between the 10 ft.
and 15 ft. height values, or 77,000 + 2/5 x
10,000 = 81,000 Btu/h. Therefore, a 4 in.
diameter vent can be used in the installation.
803.2.25 Extrapolation beyond the table entries
shall not be permitted.
803.2.26 For vent heights lower than six (6) feet
and higher than shown in the tables, engineering
methods shall be used to calculate vent
capacities. [NFPA 54:13.2]
803.2.23 Where a table permits more than one
diameter of pipe to be used for a connector or
vent, all the permitted sizes shall be permitted to
be used.
803.2.24 Interpolation shall be permitted in
calculating capacities for vent dimensions that
fall between table entries. (See Example 8-1.)
Example 8-1: Interpolating between Table
129
2007 CALIFORNIA MECHANICAL CODE
Table 8-5
Table 8-5 Type B Double-Wall Gas Vent with Single Appliance Connected Directly to Vent [NFPA 54:Table 13.1(a)]
Number of Appliances:
Single
Appliance Type:
Appliance Vent Connection:
3
Height Lateral
H
(ft)
6
8
10
15
20
30
50
100
130
4
5
Vent Diameter — D (in.)
6
Category I
Connected Directly to Vent
7
Appliance Input Rating in Thousands of Btu per Hour
8
9
L
FAN
NAT
FAN NAT
FAN
NAT
FAN
NAT
FAN
NAT
FAN
NAT
FAN
NAT
(ft) Min Max Max Min Max Max Min Max Max Min Max Max Min Max Max Min Max Max Min Max Max
0
2
4
6
0
13
21
25
78
51
49
46
46
36
34
32
0
18
30
36
152
97
94
91
86
67
64
61
0
27
39
47
251
157
153
149
141
105
103
100
0
32
50
59
375
232
227
223
205
157
153
149
0
44
66
78
524
321
316
310
285
217
211
205
0
53
79
93
698
425
419
413
370 0
285 63
279 93
273 110
897
543
536
530
470
370
362
354
0
2
5
10
0
12
23
30
88
61
57
51
53
42
40
36
0
17
32
41
175
118
113
104
100
81
77
70
0
23
41
54
295
194
187
176
166
129
124
115
0
26
52
67
447
289
280
267
255
195
188
175
0
40
68
88
631
402
392
376
345
273
263
245
0
48
81
104
847
533
522
504
450 0 1096
355 57 684
346 95 671
330 122 651
585
457
446
427
202
149
143
133
124
116
119
100
96
89
84
78
430
346
337
321
308
295
0 1057
41 711
73 697
95 675
111 654
125 634
0
2
5
8
0
2
5
10
15
0
2
5
10
15
20
0
12
23
28
0
11
22
29
35
0
10
21
28
34
48
84
57
53
49
94
69
65
59
53
97
75
71
64
58
52
50
40
38
35
58
48
45
41
37
61
51
48
44
40
35
0
16
32
39
0
15
30
40
48
0
14
29
38
46
55
0
2
5
10
15
20
30
0
9
21
27
33
56
NA
100 64 0
81 56 13
77 54 28
70 50 37
64 NA 44
58 NA 53
NA NA 73
0
2
5
10
15
20
30
50
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
0
2
5
10
15
20
30
0
8
20
26
59
NA
NA
101
86
82
76
70
NA
NA
67
61
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
0
11
27
35
42
50
69
0
10
26
33
40
47
NA
NA
165
109
103
98
191
136
130
121
112
94
75
71
66
112
93
87
82
76
0
25
42
51
0
20
39
51
61
0
18
38
50
59
69
213
166
160
150
141
132
113
128
112
108
102
96
90
NA
218
194
189
182
174
166
NA
NA
NA 0
NA 12
NA 33
NA 43
NA 50
NA 59
NA 78
NA NA
216
183
177
168
158
149
131
134
122
119
114
NA
NA
NA
0
14
36
48
57
66
88
0
14
35
45
54
63
84
276
178
171
164
327
226
219
206
195
349
250
242
229
217
206
155
120
115
109
187
150
142
135
128
202
166
160
150
142
134
0
28
53
64
0
22
49
64
76
0
20
47
62
73
84
415
263
255
247
502
339
330
315
301
540
377
367
351
337
322
235
180
173
165
285
225
217
208
198
307
249
241
228
217
206
0
42
70
84
0
38
64
84
98
0
33
62
81
94
107
583
365
356
347
716
475
463
445
429
776
531
519
499
481
464
320
247
237
227
390
316
300
288
275
0
50
83
99
0
45
76
99
115
780
483
473
463
970
633
620
600
580
415 0 1006
322 60 619
313 99 607
303 117 596
525 0 1263
414 53 815
403 90 800
386 116 777
373 134 755
575 0 1384
470 50 917
460 86 902
443 112 877
427 129 853
410 145 830
537
418
407
396
682
544
529
507
491
752
612
599
576
557
537
374
283
275
262
249
237
214
220 0
185 18
176 45
171 59
163 70
154 80
NA 104
587
432
421
405
389
374
346
336
280
273
261
249
237
219
0
27
58
77
90
102
131
853
613
600
580
560
542
507
475
394
385
371
357
343
321
0 1173
33 826
69 811
91 788
105 765
119 743
149 702
650
535
524
507
490
473
444
0
42
82
107
124
139
171
1548
1072
1055
1028
1002
977
929
407
354
347
335
321
311
290
NA
NA 0
NA 13
NA 40
NA 53
NA 62
NA 71
NA 92
NA 147
665
566
557
542
528
513
483
428
400
375
369
361
353
344
NA
NA
0
18
52
68
80
90
115
180
997
831
820
801
782
763
726
651
560
510
504
493
482
471
449
405
0
21
60
80
93
105
131
197
770
700
692
679
666
653
627
575
0
25
71
94
109
122
149
217
1908 1040
1536 935
1519 926
1492 910
1465 895
1438 880
1387 849
1288 787
397
320
312
299
287
275
250
232
206
200
190
180
169
NA
0
15
43
56
66
76
99
633
497
487
471
455
440
410
363
314
308
298
288
278
259
0
22
55
73
85
97
123
932
715
702
681
662
642
605
518
445
438
426
413
401
376
0 1297
26 975
65 960
86 935
100 911
113 888
141 844
1411
1155
1141
1118
1095
1073
1029
944
708
615
605
589
572
556
522
0
33
77
101
117
131
161
1730
1276
1259
1230
1203
1176
1125
855
700
688
668
648
628
594
952
813
798
773
747
722
670
CHIMNEYS AND VENTS
Table 8-5 continued
Table 8-5 [NFPA 54:Table 13.1(a)] Continued
Number of Appliances:
Single
Appliance Vent Connection:
Connected Directly to Vent
Appliance Type:
Category I
Vent Diameter — D (in.)
Height Lateral
H
(ft)
L
(ft)
8
0
2
5
8
6
10
15
20
30
50
100
0
2
4
6
0
2
5
10
0
2
5
10
15
0
2
5
10
15
20
0
2
5
10
15
20
30
0
2
5
10
15
20
30
0
2
5
10
15
20
30
50
10
FAN
12
NAT
FAN
NAT
14
16
18
20
Appliance Input Rating in Thousands of Btu per Hour
FAN NAT
FAN
NAT
FAN
NAT
FAN
NAT
22
FAN
24
NAT
FAN
NAT
Min Max Max MinMax Max MinMax Max Min Max Max Min Max Max Min Max Max Min Max Max Min Max Max
0
75
110
128
1121
675
668
661
570 0 1645
455 103 982
445 147 975
435 171 967
850 0 2267 1170
650 138 1346 890
640 191 1338 880
630 219 1330 870
0
178
242
276
2983
1769
1761
1753
1530
1170
1160
1150
0
225
300
341
3802
2250
2242
2235
1960 0
1480 296
1475 390
1470 437
4721
2782
2774
2767
2430
1850
1835
1820
0
360
469
523
5737
3377
3370
3363
2950 0 6853 3520
2220 426 4030 2670
2215 555 4023 2660
2210 618 4017 2650
0
68
112
142
1377
852
839
817
720 0 2036
560 93 1244
547 149 1229
525 187 1204
1060 0 2825 1450
850 124 1713 1130
829 192 1696 1105
795 238 1669 1080
0
161
243
298
3742
2256
2238
2209
1925
1480
1461
1430
0
202
300
364
4782
2868
2849
2818
2450 0
1890 264
1871 382
1840 459
5955
3556
3536
3504
3050
2340
2318
2280
0
319
458
546
7254
4322
4301
4268
3710 0 8682 4450
2840 378 5153 3390
2818 540 5132 3371
2780 641 5099 3340
930
755
738
710
688
665
0
81
135
172
195
217
2637
1694
1674
1641
1609
1578
1350
1100
1079
1045
1018
990
1195
1010
996
972
948
924
876
0
66
118
154
177
195
232
3441
2431
2406
2366
2327
2288
2214
1825
1513
1495
1466
1437
1408
1349
0
71
115
137
0
63
105
135
155
0
59
101
130
150
167
0
54
96
125
143
160
195
0
41
90
118
136
151
183
0
30
82
108
126
141
170
241
1261
770
758
746
1596
1019
1003
977
953
660 0 1858
515 98 1124
503 154 1110
490 180 1097
970 0 2571 1320
745 130 1543 1020
733 199 1528 1010
720 231 1514 1000
840 0 2380 1240
675 86 1495 985
660 140 1476 967
635 177 1446 936
610 202 1418 905
0
114
182
227
257
3323
2062
2041
2009
1976
1720
1350
1327
1289
1250
1977
1351
1332
1301
1272
1243
1189
1060
865
851
829
807
784
745
0
98
164
209
237
260
305
4252
2786
2759
2716
2674
2633
2555
2170
1800
1775
1733
1692
1650
1585
2491
1975
1955
1923
1892
1861
1802
1688
1310
1170
1159
1142
1124
1107
1071
1000
1756
1150
1133
1105
1078
1052
2231
1620
1600
1567
1536
1505
1446
0
74
127
164
187
207
246
0
44
107
142
163
181
215
292
3004
2004
1981
1944
1908
1873
1807
3925
3027
3002
2961
2920
2880
2803
2657
1550
1310
1289
1254
1220
1185
1130
2050
1820
1803
1775
1747
1719
1663
1550
0
107
174
220
248
273
0
86
151
196
222
244
287
0
72
136
180
206
226
265
350
3701
2343
2320
2282
2245
2210
4934
3409
3380
3332
3285
3239
3150
5729
4313
4282
4231
4182
4133
4037
3856
1900
1520
1498
1460
1425
1390
2550
2125
2102
2064
2026
1987
1910
2950
2550
2531
2500
2469
2438
2375
2250
0
168
251
289
0
147
229
283
318
0
139
219
273
306
335
0
127
206
259
292
319
369
0
113
191
243
274
300
347
0
95
172
223
252
277
319
415
3399
2030
2013
2000
4423
2719
2696
2659
2623
4948
3097
3071
3029
2988
2948
5725
3696
3666
3617
3570
3523
3433
6711
4554
4520
4464
4409
4356
4253
7914
5834
5797
5737
5678
5619
5505
5289
1740
1340
1330
1320
2270
1770
1748
1712
1675
2520
2000
1978
1940
1910
1880
2920
2380
2350
2300
2250
2200
2130
3440
2840
2813
2767
2721
2675
2631
4050
3500
3475
3434
3392
3351
3267
3100
0
212
311
354
0
186
283
346
385
0
175
270
334
372
404
0
159
252
316
354
384
440
0
141
234
295
330
361
412
0
120
208
268
304
330
378
486
4333
2584
2563
2552
5678
3467
3442
3402
3363
6376
3955
3926
3880
3835
3791
7420
4734
4701
4647
4594
4542
4442
8774
5864
5826
5763
5701
5641
5523
10485
7591
7548
7478
7409
7341
7209
6956
2220 0
1700 278
1685 398
1670 450
2900
2260
2235
2193
2150
0
239
355
432
479
3770
3050
3020
2970
2920
2870
2785
0
199
312
386
431
467
540
3250
2570
2544
2500
2465
2430
4460
3670
3639
3585
3534
3481
3431
5300
4600
4566
4509
4451
4394
4279
4050
0
220
337
413
459
495
5387
3196
3180
3163
7099
4304
4278
4234
4192
7988
4916
4885
4835
4786
4737
9341
5900
5863
5803
5744
5686
5574
2750
2110
2090
2070
3620
2800
2777
2739
2700
4060
3200
3174
3130
3090
3050
4750
3810
3783
3739
3695
3650
3565
0 11129 5635
171 7339 4630
283 7295 4597
355 7224 4542
396 7155 4511
433 7086 4479
494 6953 4421
0 13454 6700
138 9577 5800
245 9528 5769
318 9447 5717
358 9367 5665
387 9289 5613
446 9136 5509
572 8841 5300
0
336
476
537
0
290
426
510
564
0
269
403
489
541
585
6555
3882
3863
3850
8665
5232
5204
5159
5115
9785
5983
5950
5896
5844
5792
0
241
373
456
507
548
635
11483
7194
7155
7090
7026
6964
6842
0
169
293
374
418
452
514
659
16817
11803
11748
11658
11569
11482
11310
10979
0
209
336
419
465
506
577
13767
8980
8933
8855
8779
8704
8557
3360 0 7838 4010
2560 401 4634 3050
2545 562 4612 3040
2530 630 4602 3030
4410
3410
3385
3343
3300
0
346
501
599
665
10393
6251
6222
6175
6129
5300
4080
4057
4019
3980
5850
4650
4622
4574
4527
4480
4375
0
285
439
535
590
639
739
13848
8617
8574
8505
8437
8370
8239
7060
5600
5552
5471
5391
5310
5225
4980
3910
3880
3830
3795
3760
6940
5695
5654
5585
5546
5506
5444
8600
7200
7162
7100
7037
6975
6850
6600
0
321
475
573
631
689
0
251
394
491
542
586
672
0
204
341
436
487
523
592
752
11753
7154
7119
7063
7007
6953
16694
10788
10737
10652
10570
10488
10328
20578
14264
14204
14105
14007
13910
13720
13354
6000
4700
4662
4600
4575
4550
8430
6860
6818
6749
6710
6670
6603
10300
8800
8756
8683
8610
8537
8391
8100
131
2007 CALIFORNIA MECHANICAL CODE
Table 8-6
Table 8-6 Type B Double-Wall Vent with Single Appliance and Single-Wall Metal Connector [NFPA 54:Table 13.1(b)]
Number of Appliances:
Single
Appliance Vent Connection:
Vent Diameter — D (in.)
Single-Wall Metal Connector
Appliance Type:
Height Lateral
H
(ft)
6
8
10
15
20
30
50
100
132
L
3
4
FAN NAT
5
FAN
NAT
6
FAN
NAT
7
FAN
MinMaxMax Min Max Max MinMax Max
Min Max
0
2
5
8
37 83
39 56
NANA
NANA
123
121
151
175
0
2
5
10
0
2
5
10
15
38 77
39 51
NANA
NANA
45
36
33
31
59
60
74
83
151
96
92
89
85
66
63
60
85
85
102
114
249
156
152
147
140
104
102
99
37 87
39 61
52 56
NANA
53
41
39
34
57
59
76
97
174
117
111
100
99
80
76
68
82
82
105
132
293
193
185
171
165
128
122
112
78
78
100
125
155
186
36 93
38 69
51 63
NANA
NANA
50
39
37
33
57
47
44
39
NA
58
59
77
90
56
57
75
95
NA
164
108
102
95
190
136
128
116
NA
93
75
69
64
111
93
86
79
72
83
83
107
122
80
80
102
128
158
0
2
5
10
15
20
35 96
37 74
50 68
NANA
NANA
NANA
60
50
47
41
NA
NA
54
56
73
93
NA
NA
200
148
140
129
NA
NA
118
99
94
86
80
NA
0
2
5
10
15
20
30
33 99
36 84
48 80
NANA
NANA
NANA
NANA
66
61
NA
NA
NA
NA
NA
51
53
70
89
112
NA
NA
213
181
174
160
148
NA
NA
133 73
121 73
117 94
NA 118
NA 145
NA 176
NA NA
0
2
5
10
15
20
30
0
2
5
10
15
20
30
50
34 99
37 80
49 74
NANA
NANA
NANA
NANA
NANA
NANA
NANA
NANA
NANA
NANA
NANA
NANA
63
56
52
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
53
55
72
91
115
NA
NA
49
51
67
85
132
NA
NA
NA
211
164
157
144
131
NA
NA
214
192
186
175
162
NA
NA
NA
273
176
168
161
325
225
216
201
186
346
248
239
223
208
192
154
119
114
107
186
149
140
131
124
201
165
158
146
136
126
126
123
146
163
373
231
225
220
120
119
148
188
444
287
277
261
116
115
144
182
220
114
113
141
177
216
254
412
261
252
243
499
337
326
308
290
537
375
363
344
325
306
NAT
165
159
187
207
522
320
313
307
284
213
208
203
254
194
186
171
158
153
190
237
628
400
388
369
344
272
261
241
234
179
171
163
283
224
217
203
192
9
153
148
182
228
272
580
363
352
342
713
473
459
438
418
319
246
235
225
388
314
298
284
269
NAT
211
201
237
263
695
423
416
409
369
284
277
271
202
193
241
296
844
531
518
497
449
354
344
325
206
197
245
280
195
187
231
284
334
777
482
470
458
966
631
616
592
568
414
321
311
300
523
413
400
381
367
FAN
Min Max
267
251
295
327
1002
617
604
591
244
232
287
349
404
1259
812
795
768
742
253
242
299
363
772
528
514
491
469
448
428
344
334
316
301
285
190 1053
182 708
224 692
277 666
325 640
374 616
573
468
457
437
419
400
238
227
279
339
393
448
361
312
305
292
280
267
NA
138
133
164
203
244
285
373
928
712
696
671
646
622
573
515
443
435
420
405
389
NA
176 1292
168 971
204 953
253 923
299 894
345 866
442 809
704
613
602
583
562
543
502
220
209
257
313
363
415
521
584
429
417
397
377
357
NA
334
279
271
257
242
228
NA
NA 69
NA 70
NA 90
NA 113
NA 138
NA 168
NA 231
NA NA
403
351
342
324
310
295
264
NA
NA
NA
NA
NA
NA
NA
NA
NA
100
98
125
153
188
224
301
NA
659
563
551
532
511
487
448
NA
395
373
366
354
343
NA
NA
NA
144
139
171
213
255
298
389
131
125
156
191
230
270
355
540
849
610
595
570
547
524
477
991
828
813
789
764
739
685
584
472
392
382
367
349
333
305
555
508
501
486
473
458
NA
NA
184 1168
175 823
215 806
265 777
312 750
360 723
461 670
166
158
194
238
281
325
418
617
1404
1152
1134
1104
1075
1046
988
866
647
533
521
501
481
461
426
765
698
688
672
656
639
NA
NA
894
541
533
526
258
246
305
344
149
144
178
222
264
309
110
109
136
171
208
246
NA
629
495
482
461
441
420
376
161
155
193
223
FAN
Min Max Max
306
248
239
224
210
196
219
183
173
168
157
NA
NA
105
104
131
162
199
236
315
NAT
204
156
152
148
372
281
271
255
239
223
NA
230
205
198
186
174
NA
NA
FAN
Max Min Max Max
127 76
111 76
106 98
98 122
NA 151
NA 181
NA NA
394
318
308
292
275
257
NA
8
Appliance Input Rating in Thousands of Btu per Hour
(ft)
0
2
4
6
Category I
229
219
269
327
379
433
541
207
196
240
293
342
391
491
711
1093
681
667
643
NAT
10
FAN
Max Min Max
469
368
360
352
371
347
409
449
1118
673
664
656
584
456
443
423
351
332
409
492
536
417
404
392
681
543
526
501
484
360
339
418
470
336
319
392
470
540
12
NAT
537
498
584
638
1639
979
971
962
1373
849
834
808
718
559
544
520
507
475
584
688
2031 1057
1242 848
1224 825
1194 788
927
754
734
702
677
651
473
443
547
646
730
808
2631
1689
1665
1626
1587
1550
1346
1098
1074
1037
1005
973
3432
2426
2396
2347
2299
2251
2159
1818
1509
1490
1455
1421
1387
1318
1257
768
754
740
1591
1015
997
966
937
658
513
500
486
838
673
657
628
601
750
611
596
570
549
526
326
309
381
457
526
592
1751
1146
1126
1092
1060
1028
1724
1273
1252
1217
1183
1150
1086
948
811
795
765
736
708
649
295
280
347
418
481
544
674
2223 1189
1615 1007
1591 991
1551 963
1512 934
1473 906
1399 848
1900
1532
1511
1477
1443
1410
1343
1205
852
698
684
662
638
615
574
1033
933
921
902
884
864
824
NA
312
296
366
440
507
570
704
273
259
322
389
447
507
631
138
NAT
569
453
443
433
1379
914
896
866
838
810
1542
1069
1049
1017
985
955
895
FAN
Max Min Max Max
1971 1056
1346 863
1324 846
1287 821
1251 794
1216 768
1147 720
2479
1970
1945
1905
1865
1825
1747
1591
521
486
598
665
488
457
562
664
750
454
424
524
620
702
780
937
428
401
496
589
668
741
892
1852
1120
1104
1089
849
648
638
627
967
743
730
715
2374 1237
1491 983
1469 963
1433 928
1399 894
2996
1999
1971
1927
1884
1841
1759
1300 395 3912
1168 371 3021
1153 460 2990
1133 547 2938
1110 618 2888
1087 690 2838
1041 834 2739
NA 1138 2547
1545
1308
1283
1243
1205
1166
1101
2042
1817
1796
1763
1730
1696
1627
1489
CHIMNEYS AND VENTS
Table 8-7
Table 8-7 Masonry Chimney with Single Appliance and Type B Double-Wall Connector [NFPA 54:Table 13.1(c)]
Number of Appliances:
Single
Appliance Vent Connection:
Type B Double-Wall Connector
Appliance Type:
Category I
Type B Double-Wall Connector Diameter — D (in.)
Height Lateral
H
L
(ft)
(ft)
8
2
5
8
6
10
15
20
30
50
2
5
2
5
10
2
5
10
15
2
5
10
15
20
2
5
10
15
20
30
2
5
10
15
20
30
Minimum
Internal Area
of Chimney
(Square Inches)
Maximum
Internal Area
of Chimney
(Square Inches)
3
4
FAN
NAT FAN
5
NAT
To be used with chimney areas within the size limits at bottom
FAN
6
7
8
9
Appliance Input Rating in Thousands of Btu per Hour
NAT
FAN
NAT
FAN
NAT
FAN NAT
FAN
NAT
10
FAN
12
NAT
FAN NAT
MinMax Max Min Max Max Min Max Max MinMax Max Min Max Max Min Max Max
Min Max Max
Min Max Max Min Max Max
NANA 29
NANA 26
NANA 24
84 590 350
NA NA 328
NA NA 318
100 728 446 139 1024 651
149 711 423 201 1007 640
173 695 410 231 990 623
NANA 28
NANA 25
NA NA 52
NA NA 49
NA NA 86
NA NA 82
NA NA
NA NA
130 NA NA 180 NA NA 247
117 NA NA 165 NA NA 231
NANA 31
NANA 28
NANA 25
NA NA 61
NA NA 57
NA NA 50
NA NA 103 NA NA
NA NA 96 NA NA
NA NA 87 NA NA
162 NA NA 221 68 519 298
148 NA NA 204 NA NA 277
139 NA NA 191 NA NA 263
NANA
NANA
NANA
NANA
35
35
28
NA
NANA
NANA
NANA
NANA
NANA
NANA
41
NA
NA
NA
NA
NA
NANA
NANA
NANA
NANA
NANA
NANA
NANA
NANA
NANA
NANA
NANA
12
49
38
36
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA NA 55
NA NA 52
NA NA 48
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
67
62
55
48
NA
NA
NA
NA
NA
74
68
60
NA
NA
NA
NA
NA
NA
NA
NA
92
NA
NA
NA
NA
NA
19
88
82
76
67
NA
NA
NA
NA NA 93
NA NA 88
NA NA 83
NA NA
NA NA
NA NA
NA
NA
NA
NA
NA
NA
NA
NA
114
107
97
89
NA NA
NA NA
NA NA
NA NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
137
128
115
107
91
NA
NA NA
NA NA
NA NA
NA NA
NA NA
NA NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
28
137
124
116
107
97
83
161
151
138
127
NA
NA
NA NA
NA NA
NA NA
NA NA
NA NA
NA NA
NA NA
NA NA
NA NA
NA NA
NA NA
38
198
145 NA NA 198 NA NA 266
134 NA NA 183 NA NA 247
127 NA NA 175 NA NA 239
179 53 475 250 64 613
164 NA NA 231 99 594
153 NA NA 216 126 565
141 NA NA 201 NA NA
336
313
296
281
201 51 522 274 61 678
184 80 503 254 95 658
172 NA NA 237 122 627
159 NA NA 220 NA NA
148 NA NA 206 NA NA
375
350
332
314
296
251
230
215
199
185
NA
477
445
424
400
376
327
216
198
184
171
159
NA
47
75
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
581
561
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
50
269
303 57 762 421
281 90 741 393
263 115 709 373
243 NA NA 353
227 NA NA 332
188 NA NA 288
351
323
304
282
264
NA
51 840
83 819
NA NA
NA NA
NA NA
NA NA
63
352
NA NA 320
NA NA 298
82 655 388
124 638 365
155 610 347
77
118
148
171
73
113
143
165
186
68
106
135
156
176
NA
61
98
126
146
165
NA
779
759
727
698
867
845
811
780
750
985
962
927
893
860
NA
1106
1083
1047
1010
977
NA
78
445
441
416
394
375
491
463
440
418
397
558
526
500
476
450
416
633
596
567
539
511
468
NA NA 401 NA NA 581
NA NA 376 NA NA 561
98 810 491 136 1144 724
146 791 466 196 1124 712
182 762 444 240 1093 668
92
139
173
198
87
133
167
191
214
81
125
158
181
203
249
72
116
147
170
190
233
968
946
912
880
562
533
567
485
1083 627
1059 597
1022 566
987 541
955 513
1240 717
1216 683
1176 648
1139 621
1103 592
1035 555
1413 812
1387 774
1347 733
1307 702
1269 669
1196 623
95
550
127
186
229
259
121
179
221
251
277
111
169
210
239
264
318
99
155
195
222
246
295
1376
1352
1315
1280
1548
1523
1482
1443
1406
1793
1766
1721
1679
1638
1560
2080
2052
2006
1961
1916
1832
132
841
828
777
742
953
933
879
840
807
1112
1094
1025
981
940
877
1243
1225
1147
1099
1050
984
792
133
2007 CALIFORNIA MECHANICAL CODE
Table 8-8
Table 8-8 Masonry Chimney with Single Appliance and Single-Wall Metal Connector [NFPA 54:Table 13.1(d)]
Number of Appliances:
Single
Appliance Vent Connection:
Single-Wall Metal Connector
Appliance Type:
3
Height Lateral
H
(ft.)
6
8
10
15
20
FAN
2
NA NA
28
NA NA
52
NA NA
86
2
NA NA
29
NA NA
55
NA NA
93
5
5
8
2
5
NA NA
NA NA
NA NA
NA NA
NA NA
10
NA NA
5
NA NA
2
NA NA
10
NA NA
2
NA NA
15
5
25
26
23
31
28
24
35
32
27
NA NA NA
NA NA
38
35
10
NA NA NA
20
NA NA NA
2
5
NA NA NA
NA NA
41
NA NA NA
10
NA NA NA
20
NA NA NA
30
2
5
NA NA NA
NA NA NA
NA NA NA
NA NA NA
10
NA NA NA
20
NA NA NA
15
30
Minimum
Internal Area of
Chimney
(Square Inches)
Maximum
Internal Area of
Chimney
(Square Inches)
134
FAN NAT FAN
6
7
8
9
Appliance Input Rating in Thousands of Btu per Hour
L
15
50
NAT
5
Single-Wall Metal Connector Diameter — D (in.)
To be used with chimney areas within the size limits at bottom
NAT
(ft.) Min Max Max Min Max Max Min Max Max
15
30
4
NA NA NA
NA NA NA
12
49
NA NA
NA NA
NA NA
NA NA
NA NA
NA NA
NA NA
NA NA
NA NA
NA NA
48
51
47
61
56
49
67
61
54
46
NA NA
NA NA
NA NA
81
87
82
NA NA
102
NA NA
86
NA NA
95
NA NA
113
NA NA
96
NA NA
NA NA
106
87
FAN NAT
NA
NA
NA NA 560
NA
NA NA
145
NA
NA NA
NA NA
NA NA
NA NA
NA NA
NA NA
NA NA
NA NA
NA NA
116
133
126
161
147
137
178
144
66
NA NA
113
NA NA
182
NA NA NA NA NA
88
NA NA NA NA NA
NA
NA NA NA NA NA
149
NA NA
91
NA NA
NA NA NA NA NA
NA NA NA NA NA
NA NA NA NA NA
NA NA NA NA NA
19
88
NA NA
NA
NA
NA NA
NA NA
NA NA
28
137
NA
211
611
335
230
591
NA
NA
349
NA
317
NA
NA
NA
271
654
334
NA
NA
382
NA
400
725
445
NA
408
NA
327
NA
NA
387
373
808
NA
375
422
490
NA NA 580
549 1021 650
673 1003 638
747 985 621
536 1142 722
635
364
459
789
465
657 1121 710
776
440
362
965
560
520 1373 840
261
NA
NA
312
325
755
264
297
345
414
547
444
758
942
531
771 1088 665
637 1348 825
749 1309 774
520
273
206
675
374
258
864
490
252 1079 625
508 1544 950
NA
235
198
252
NA
255
312
NA
655
622
278
348
330
217
NA
NA
311
578
302
200
759
420
NA
260
703
370
NA
NA
NA
202
279
NA
NA
NA
NA
50
269
NA
245
300
NA
737
806
442
NA
NA
281
327
475
370
428
NA
437
873
481
433 1055 594
517 1016 562
623 1518 930
733 1475 875
539
823 1434 835
982
556
340 1237 715
489 1789 1110
920
496
500 1168 644
392
524
663
979
841 1272 738
591
944
510
417 1210 680
911 1394 800
600 1760 1090
708 1713 1020
884
471
572 1128 615
798 1668 975
NA
408
NA
544
1055 1539 865
NA
NA
461
606
414
958
249
372
773
306
182
837
382
391
349
191
842
NA
NA
NA
317
NA
NA
NA
692
292
240
223
452
907
441
504
301
NA
261
NA
319
NA
531
NA
NA
NA
NA
392
NA
180
297
249
189
212
NA
518
237
276
350
NA
216
NA
NA
NA
195
NA
246
NA
NA
NA
265
NA
203
250
38
198
NA
NA
NA
NA
722
NA
155
NA
230
392
NA
NA
220
247
NA
294
168
228
NA NA
124
158
174
NA
NA
NA
NA NA
136
NA
182
NA
NA
NA
NA
NA NA
NA
164
214
196
NA NA
160
163
NA
NA
NA NA
NA NA
NA
NA
215
105
473
156
NA NA
NA NA NA NA NA
NA
NA
136
NA NA
NA
NA
NA NA
127
166
NA
183
81
NA NA
NA
NA
NA
NA NA
75
NA
197
NA
NA
170
NA NA
NA
NA
138
151
NA NA
NA NA
NA
180
NA
105
NA NA
NA
NA
NA
NA NA
NA NA
NA
163
59
80
FAN NAT
NA
130
NA NA
NA NA NA NA NA
FAN NAT
NA NA
NA NA
200
95
FAN NAT
Min Max Max
NA NA
NA NA NA NA NA
NAT
Min Max Max Min Max Max
123
115
FAN
Min Max Max
NA NA
NA NA
NAT
12
Max Max
73
67
FAN
10
Min Max Max Min
NA NA
NA NA
Category I
445
238 1103 631
643 1089 585
NA
323 1408 810
883 1624 932
463 2076 1240
321
NA
NA
442
293 1078 593
398 1381 770
571 2044 1220
278
NA
NA
395
NA
NA
533
546 1294 695
761 1945 1090
318
NA
NA
458
NA
1009 1805 970
258
NA
NA
NA
NA
NA
NA
NA
63
352
420
370
355 1038 562
NA
NA
78
445
504
447 1337 728
616 1251 660
NA
95
550
610
674 1994 1140
844 1898 1040
132
792
CHIMNEYS AND VENTS
Table 8-9
Table 8-9 Single-Wall Metal Pipe or Type B Asbestos Cement Vent with Single Appliance [NFPA 54:Table 13.1(e)]
Number of Appliances:
Single
Appliance Vent Connection:
Connected Directly to Pipe or Vent
Appliance Type:
Height
H
(ft)
Lateral
L
(ft)
8
0
2
5
10
6
10
15
20
30
50
0
2
5
3
Draft Hood-Equipment
Diameter - D (in.)
To be used with chimney area within the size limits at bottom
4
5
6
7
8
Appliance Input Rating in Thousands of Btu per Hour
10
Maximum Appliance Input Rating in Thousands of Btu per Hour
12
39
31
28
70
55
51
116
94
88
170
141
128
232
194
177
312
260
242
500
415
390
750
620
600
0
2
5
10
15
45
35
32
27
NA
84
67
61
54
46
138
111
104
94
84
202
168
153
143
130
279
233
215
200
186
372
311
289
274
258
606
505
480
455
432
912
760
724
700
666
0
2
5
10
15
20
53
42
38
32
NA
NA
0
2
5
10
15
20
0
2
5
10
15
20
30
0
2
5
10
15
20
30
42
32
29
24
49
39
35
30
NA
NA
56
44
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
76
61
56
49
91
72
67
58
50
NA
101
80
74
65
55
NA
108
84
78
68
NA
NA
NA
120
95
NA
NA
NA
NA
NA
126
102
95
86
151
122
110
103
93
82
163
136
123
115
104
91
183
148
137
125
113
99
NA
210
171
159
146
NA
NA
NA
185
154
141
131
223
186
170
158
144
132
252
210
192
178
163
149
276
230
210
196
177
163
NA
310
260
234
221
200
185
NA
252
210
194
180
312
260
240
223
207
195
342
286
264
246
228
214
384
320
296
274
258
240
192
443
370
342
318
292
276
222
340
284
264
250
542
451
430
406
420
350
325
308
291
273
684
570
540
514
488
466
529
441
410
388
366
344
295
878
730
694
656
625
596
540
470
392
364
345
326
306
590
492
474
456
407
384
330
770
641
610
571
550
525
980
820
780
730
705
670
605
815
680
648
625
1040
865
825
795
760
726
1190
990
945
910
870
832
1370
1140
1080
1050
1000
960
890
1550
1290
1230
1190
1130
1080
1010
135
2007 CALIFORNIA MECHANICAL CODE
Table 8-10
Table 8-10 Type B Double-Wall Vent with Two or More Appliances and Type B Double-Wall Connector
[NFPA 54:Table 13.2(a)]
Number of Appliances:
Two or More
Appliance Vent Connection:
Type B Double-Wall Connector
Appliance Type:
3
4
Category I
Type B Double-Wall Vent and Connector Diameter — D (in.)
5
6
7
8
9
Appliance Input Rating in Thousands of Btu per Hour
10
Height Rise FAN NAT FAN NAT FAN NAT FAN NAT FAN
NAT FAN NAT FAN
NAT FAN NAT
H
R
(ft.) (ft.) Min MaxMaxMin MaxMaxMinMax MaxMin Max MaxMinMax MaxMin Max Max Min Max Max MinMaxMax
6
8
10
15
20
30
50
100
1
2
3
22
23
24
37
41
44
26
31
35
35
37
38
66 46
75 55
81 62
46 106
48 121
49 132
58 164 104 77 225 142 92 296
60 183 124 79 253 168 95 333
62 199 139 82 275 189 97 363
185
220
248
109 376
112 424
114 463
237 128 466 289
282 131 526 345
317 134 575 386
1
2
3
22
23
24
43
47
50
28
33
37
34
36
37
78 50
86 59
92 67
49 123 78 65 189 113 89 257 154 106 341
51 136 93 67 206 134 91 282 182 109 374
52 146 104 69 220 150 94 303 205 111 402
200
238
268
125 436
128 479
131 515
257 146 542 314
305 149 596 372
342 152 642 417
1
2
3
1
2
3
1
2
3
1
2
3
1
2
3
1
2
3
22
23
24
21
22
24
21
22
23
20
21
22
19
21
22
18
19
20
40
44
47
50
53
55
54
57
60
62
64
66
71
73
75
82
83
84
27
32
36
30
35
40
31
37
42
33
39
44
36
43
48
37
44
50
35
36
37
33
35
36
89 53
96 63
102 71
31
33
34
113 59
118 70
123 79
33
34
35
30
32
33
28
30
31
Common Vent Capacity
Vent
Height
H
(ft)
6
8
10
15
20
30
50
100
136
72 48
80 57
87 64
4
99 56
105 66
110 74
133 64
137 76
141 86
158 66
161 79
163 89
5
72
86
96
49 114 76 64 176 109 84 243 148 100 320
51 128 90 66 195 129 86 269 175 103 356
53 139 101 67 210 145 88 290 198 105 384
47 142 83 64 220 120 88 298 163 110 389
49 153 99 66 235 142 91 320 193 112 419
51 163 111 68 248 160 93 339 218 115 445
46 157 87 62 246 125 86 334 171 107 436
48 167 104 64 259 149 89 354 202 110 463
50 176 116 66 271 168 91 371 228 113 486
45 181 93 60 288 134 83 391 182 103 512
47 190 110 62 299 158 85 408 215 105 535
48 198 124 64 309 178 88 423 242 108 555
43 216 101 57 349 145 78 477 197 97 627
45 223 119 59 358 172 81 490 234 100 645
46 229 134 61 366 194 83 502 263 103 661
40 262 104 53 442 150 73 611 204 91 810
42 267 123 55 447 178 75 619 242 94 822
44 272 138 57 452 200 78 627 272 97 834
194
230
258
214
253
286
224
265
300
238
282
317
257
306
343
266
316
355
118 408
121 454
123 492
134 493
137 532
140 565
131 552
134 587
137 618
125 649
129 679
132 706
120 797
123 820
126 842
7
273 162 609 333
323 165 658 394
365 167 700 444
285 158 681 347
339 161 725 414
383 164 764 466
305 151 802 372
360 155 840 439
405 158 874 494
330 144 984 403
392 148 1014 478
441 151 1043 538
112 1038 341 135 1285 417
115 1054 405 139 1306 494
118 1069 455 142 1327 555
Type B Double-Wall Common Vent Diameter — D (in.)
6
248 138 507 303
294 141 564 358
330 143 612 402
8
9
10
Combined Appliance Input Rating in Thousands of Btu per Hour
FAN FAN NAT FAN FAN NAT FAN FAN NAT FAN FAN
NAT FAN FAN NAT FAN FAN NAT FAN FAN NAT
+FAN+NAT+NAT+FAN +NAT +NAT+FAN+NAT +NAT+FAN +NAT +NAT+FAN +NAT +NAT+FAN+NAT+NAT+FAN+NAT+NAT
92
101
110
125
136
152
167
175
81
65
90
73
97
79
112 91
123 102
138 118
153 134
163 NA
140
155
169
195
215
244
279
311
116
129
141
164
183
210
244
277
103
114
124
144
160
185
214
NA
204
224
243
283
314
361
421
489
161
178
194
228
255
297
353
421
147
163
178
206
229
266
310
NA
309
339
367
427
475
547
641
751
248
275
299
352
394
459
547
658
200 404
223 444
242 477
280 556
310 621
360 720
423 854
479 1025
314
348
377
444
499
585
706
873
260
290
315
365
405
470
550
625
547
602
649
753
842
979
1164
1408
434
480
522
612
688
808
977
1215
335
378
405
465
523
605
705
800
672
740
800
924
1035
1209
1451
1784
520
577
627
733
826
975
1188
1502
410
465
495
565
640
740
860
975
CHIMNEYS AND VENTS
Table 8-10 continued
Table 8-10 [NFPA 54:Table 13.2(a)] Continued
Vent Connector
Height Rise
H
R
(ft)
(ft)
6
2
4
6
2
4
6
2
4
6
2
4
6
2
4
6
2
4
6
2
4
6
2
4
6
8
10
15
20
30
50
100
12
14
H
(ft.)
6
Appliance Type:
Appliance Vent Connection:
764 496
897 616
NA NA
822 516
952 644
1050 772
870 536
997 664
1095 792
967 568
1085 712
1181 856
1051 596
1162 748
1253 900
1217 632
1316 792
1400 952
1479 689
1561 860
1631 1031
1923 712
1984 888
2035 1064
223
230
NA
238
244
252
249
256
263
272
279
286
291
298
307
286
294
303
273
281
290
254
263
272
12
16
18
1046
1231
NA
1126
1307
1445
1195
1371
1509
1334
1499
1632
1443
1597
1726
1664
1802
1920
2023
2139
2242
2644
2731
2811
14
653
827
NA
696
884
1072
730
924
1118
790
1006
1222
840
1064
1288
910
1160
1410
1007
1291
1575
1050
1346
1642
281
287
NA
298
305
313
311
318
325
336
344
351
357
365
373
367
376
384
350
359
369
326
336
346
1371
1617
NA
1478
1719
1902
1570
1804
1989
1760
1978
2157
1911
2116
2287
2183
2366
2524
2659
2814
2951
3490
3606
3714
853
1081
NA
910
1150
1390
955
1205
1455
1030
1320
1610
1095
1395
1695
1190
1510
1830
1315
1685
2055
1370
1760
2150
990
815 1735
1336 1065
10
1076
841 712 1542 1200
995 2093
1625 1300
20
1405 1116 916 2006 1588 1290 2722
30
50
100
1247
24
346
352
NA
365
372
380
379
387
395
408
416
424
430
438
450
461
474
485
435
447
461
402
414
426
1772
2069
NA
1920
2211
2434
2049
2332
2556
2317
2579
2796
2533
2778
2984
2891
3110
3299
3548
3730
3893
4707
4842
4968
NAT FAN
NAT
FAN NAT FAN NAT
Max Min Max Max Min Max Max MinMax Max
1080
1370
NA
1150
1460
1770
1205
1535
1865
1305
1665
2025
1385
1765
2145
1540
1920
2340
1665
2135
2605
1740
2220
2700
NA
NA
NA
NA
471
478
NA
486
494
NA
523
533
NA
554
567
NA
619
632
NA
580
594
NA
523
539
FAN FAN NAT FAN FAN NAT FAN FAN NAT FAN FAN NAT FAN
+FAN +NAT+NAT+FAN +NAT +NAT +FAN +NAT +NAT
994
22
NA
NA
NA
NA
2737
3018
NA
2887
3169
NA
3197
3470
NA
3447
3708
NA
3840
4080
NA
4601
4808
NA
5982
6143
NA
NA
NA
NA
1800
2180
NA
1890
2290
NA
2060
2510
NA
2180
2650
NA
2365
2875
NA
2633
3208
NA
2750
3350
NA
NA
NA
NA
560
568
NA
581
589
NA
624
634
NA
661
671
NA
728
741
NA
709
724
NA
639
654
NA
NA
NA
NA
3319
3665
NA
3502
3849
NA
3881
4216
NA
4190
4511
NA
4861
4976
NA
5569
5826
NA
7254
7453
NA
NA
NA
NA
2180
2640
NA
2280
2760
NA
2490
3030
NA
2630
3190
NA
2860
3480
NA
3185
3885
NA
3330
4070
Combined Appliance Input Rating in Thousands of Btu per Hour
696 588 1284
15
20
Type B Double-Wall Common Vent Diameter — D (in.)
16
18
20
22
900
8
Category I
Type B Double-Wall Vent Connector
Appliance Input Rating Limits in Thousands of Btu per Hour
FAN NAT FAN
NAT FAN NAT FAN
Min Max Max Min Max Max Min Max Max Min Max
174
180
NA
186
192
198
196
201
207
214
221
228
223
230
237
216
223
231
206
213
221
192
200
208
Two or More
Type B Double-Wall Vent Connector Diameter – D (in.)
Common Vent Capacity
Vent
Height
Number of Appliances:
773 652 1423 1103
912 1927
986 825 1794 1410 1158 2440
1658 1327 1025 2373 1892 1525 3220
2024 1640 1280 2911 2347 1863 3964
2569 2131 1670 3732 3076
2450 5125
1491 1190
1910 1510
2147 1690
2558 1990
3183 2430
4202 3200
1660 3488 2677
1970 4206 3226 2390
2665
2030 4241 3278
2400 5123 3957 2920
2507 1936
3162
2439
2727 2113
1645
3184 2484
3561 2798
4197 3326
5184 4149
6749 5509
1510
1910
2140
2520
3075
4050
3444
4026
4548
5303
6567
8597
24
2180
+NAT +NAT
2838
NA
NA
NA
NA
2590
3130
NA
2710
3270
NA
2960
3600
NA
3130
3790
NA
3410
4150
NA
3790
4620
NA
3950
4810
NAT FAN FAN NAT FAN FAN NAT
+FAN
1345
NA
NA
NA
NA
3957
4373
NA
4175
4593
NA
4631
5035
NA
5005
5392
NA
5606
5961
NA
6633
6943
NA
8650
8892
FAN
+FAN +NAT +NAT
2253 1732
NA
NA
NA
NA
662
669
NA
686
694
NA
734
743
NA
772
785
NA
847
860
NA
851
867
NA
769
786
3133
3552
4193
5240
6986
+FAN+NAT +NAT +FAN +NAT +NAT
1860 3890 2998
2360 4971 3862
2640 5573 4352
3110 6539 5157
3800 8116 6458
5000 10681 8648
2200 4695 3616 2680
2790 6016 4670 3400
3120 6749 5261 3800
3680 7940 6247 4480
4500 9837 7813 5475
5920 13004 10499 7200
137
2007 CALIFORNIA MECHANICAL CODE
Table 8-11
Table 8-11 Type B Double-Wall Vent with Two or More Appliances and Single-Wall Metal Connector [NFPA 54:Table 13.2(b)]
Number of Appliances:
Appliance Type:
Two or More
Category I
Appliance Vent Connection: Single-Wall Metal Connector
3
Vent Connector
Height
Rise
H
(ft)
6
8
10
15
20
30
50
100
R
1
2
3
1
2
3
1
2
3
1
2
3
1
2
3
1
2
3
1
2
3
1
2
3
FAN
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
49
52
55
47
51
54
46
49
52
45
48
51
NAT
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
56
59
62
60
62
64
69
71
72
79
80
81
26
31
34
27
32
35
28
33
36
29
34
39
30
36
40
31
37
42
34
40
45
34
41
46
FAN
Height
H
4
NAT
NA
NA
NA
NA
NA
NA
NA
84
89
79
83
87
78
82
87
77
81
85
75
79
83
71
75
79
NA
NA
NA
NA
NA
NA
NA
85
91
87
94
100
97
103
107
110
115
119
128
132
136
150
153
157
46
55
62
48
57
64
50
59
67
52
62
70
54
64
72
57
67
76
60
72
82
61
73
85
FAN
NAT
FAN
NAT
NA
NA
121
NA
125
130
119
124
129
116
121
127
115
120
125
112
117
122
109
114
119
104
110
114
NA
NA
131
NA
126
138
121
134
144
138
150
160
152
163
172
175
185
193
207
215
221
249
255
260
71
85
95
75
89
100
77
91
102
81
97
109
84
101
113
89
106
120
96
113
123
98
115
129
NA
168
175
NA
184
191
182
189
197
177
185
193
175
182
190
169
177
185
162
170
178
153
160
168
NA
182
198
NA
193
208
186
203
217
214
230
243
238
252
264
278
290
300
336
345
353
424
428
433
102
123
138
106
127
144
110
132
148
116
138
157
120
144
164
129
152
172
137
164
186
140
167
190
FAN
Min Max
207
215
222
226
234
241
240
248
257
238
246
255
233
243
252
226
236
244
217
226
235
205
212
222
223
251
273
240
266
287
253
278
299
291
314
333
325
346
363
380
397
412
460
473
486
585
593
603
NAT
Max
140
167
188
145
173
197
150
183
203
158
189
215
165
197
223
175
208
235
188
223
252
192
228
256
8
5
10
15
20
30
50
100
138
NA
78
64
NA
113
NA
94
76
163
137
87
71
NA
NAT
262
271
279
285
293
302
302
311
320
312
321
331
306
317
326
296
307
316
284
294
304
269
279
289
293
331
361
316
353
381
335
369
398
380
411
438
425
453
476
497
521
542
604
623
640
774
788
801
183
219
247
191
228
256
196
235
265
208
248
281
217
259
294
230
274
309
245
293
331
249
299
339
FAN NAT
FAN FAN NAT
FAN FAN NAT
FAN
99
126
111
218
331
436
120
200
158
144
237
189
174
173
159
304
244
196
357
292
236
269
218
398
467
FAN
FAN
NAT
Min Max Max Min Max Max
325
334
344
352
360
370
372
381
391
397
407
418
390
400
412
378
389
400
364
376
387
345
358
368
373
422
462
403
450
489
429
473
511
482
522
557
538
574
607
630
662
690
768
793
816
993
1011
1027
234
281
316
244
292
328
252
302
339
266
317
360
276
331
375
294
349
394
314
375
423
321
383
431
6
7
8
9
Combined Appliance Input Rating in Thousands of Btu per Hour
FAN FAN NAT FAN FAN NAT
NA
FAN
Min Max Max
Type B Double-Wall Vent Diameter — D (in.)
(ft) +FAN +NAT+NAT +FAN +NAT +NAT +FAN +NAT +NAT +FAN +NAT +NAT +FAN
6
10
Appliance Input Rating Limits in Thousands of Btu per Hour
Min Max Max Min Max Max Min Max Max
Common Vent Capacity
Vent
Single-Wall Metal Vent Connector Diameter — D (in.)
5
6
7
8
9
4
Min Max Max
(ft)
Vent Connector Capacity
447
458
468
481
492
501
506
517
528
556
568
579
546
558
570
528
541
555
507
520
535
476
490
506
463
524
574
502
560
609
534
589
637
596
646
690
664
709
750
779
819
855
951
983
1013
1236
1259
1280
286
344
385
299
355
400
308
368
413
324
387
437
336
403
457
358
425
482
384
458
518
393
469
527
10
NAT FAN FAN NAT FAN FAN NAT
+NAT +NAT +FAN +NAT +NAT+FAN +NAT+NAT
310
342
369
257
541
429
332
665
515
309
638
512
398
787
617
285
592
473
373
730
569
407
460
487
121
108
88
189
159
140
275
221
200
416
343
274
544
434
357
738
599
456
905
718
553
145
132
113
236
202
180
350
286
257
533
446
349
703
570
459
958
790
593 1183
952
723
153
NA
131
159
166
118
145
98
128
208
268
297
177
233
263
156
208
NA
305
406
469
247
337
398
223
296
NA
463
622
726
383
529
633
302
410
464
606
833
999
487
686
846
395
535
606
824
1139
1378
673
954
1185
512 1013
689 1418
780 1741
808
1157
1459
626
838
948
CHIMNEYS AND VENTS
Table 8-12
Table 8-12 Masonry Chimney with Two or More Appliances and Type B Double-Wall Connector [NFPA 54:Table 13.2(c)]
Number of Appliances:
Appliance Type:
Appliance Vent Connection:
Vent Connector Capacity
Vent Connector
Height Rise
H
R
6
1
2
3
1
2
3
1
2
3
1
2
3
1
2
3
1
2
3
1
2
3
1
2
3
(ft.) (ft.)
8
10
15
20
30
50
100
3
Type B Double-Wall Vent Connector Diameter — D (in.)
4
FAN
NAT FAN
Two or More
Category I
Type B Double-Wall Connector
5
6
7
8
Appliance Input Rating Limits in Thousands of Btu per Hour
FAN
NAT
FAN NAT FAN
NAT
FAN
NAT
NAT
9
FAN
MinMax Max Min Max Max Min Max Max Min Max Max Min Max Max Min Max Max Min
24
26
27
24
26
27
24
26
27
24
25
26
24
25
26
24
25
26
23
24
26
23
24
25
33
43
49
39
47
52
42
50
55
48
55
59
52
58
63
54
60
64
51
59
64
46
53
59
21
28
34
22
29
34
22
29
35
23
31
35
24
31
35
25
32
36
25
32
36
24
31
35
39
41
42
39
40
42
38
40
41
38
39
41
37
39
40
37
38
40
36
37
39
35
37
38
62
79
92
72
87
97
80
93
105
93
105
115
102
114
123
111
122
131
116
127
135
108
120
130
40
52
61
41
53
62
42
54
63
44
55
64
46
56
65
48
58
66
51
61
69
50
60
68
52
53
55
55
57
59
55
57
58
54
56
57
53
55
57
52
54
56
51
53
55
49
51
53
Common Vent Capacity
12
106
133
155
117
140
159
130
153
170
154
174
189
172
190
204
192
208
221
209
225
237
208
224
237
67
85
97
69
86
98
71
87
100
74
89
102
77
91
104
82
95
107
89
102
115
92
105
118
65
67
69
71
73
75
74
76
78
72
74
76
71
73
75
69
72
74
67
70
72
65
67
69
194
230
262
213
246
269
232
261
284
277
299
319
313
335
353
357
376
392
405
421
435
428
444
458
101
124
143
105
127
145
108
129
148
114
134
153
119
138
157
127
145
163
143
161
180
155
174
193
87
89
91
94
97
99
101
103
106
100
103
105
98
101
104
96
99
101
92
95
98
88
92
94
274
324
369
304
350
383
324
366
397
384
419
448
437
467
493
504
531
554
582
604
624
640
660
679
141
173
203
148
179
206
153
184
209
164
192
215
173
199
222
187
209
233
213
235
260
237
260
285
104
107
109
113
116
119
120
123
126
125
128
131
123
126
129
119
122
125
115
118
121
109
113
116
370
436
491
414
473
517
444
498
540
511
558
597
584
625
661
680
715
746
798
827
854
907
933
956
201
232
270
210
240
276
216
247
281
229
260
292
239
270
301
255
287
317
294
326
357
334
368
399
10
124
127
129
134
137
139
142
145
147
153
156
159
150
153
156
145
149
152
140
143
147
134
138
141
NAT
FAN
479
562
633
539
615
672
582
652
705
658
718
760
752
805
851
883
928
968
1049
1085
1118
1222
1253
1282
253
300
349
267
311
358
277
321
366
297
339
382
312
354
396
337
378
418
392
433
474
454
497
540
145
148
151
156
160
163
165
168
171
184
187
190
180
184
187
175
179
182
168
172
176
161
165
169
Minimum Internal Area of Masonry Chimney Flue (in.2)
28
38
50
63
78
19
NAT
Max Max Min Max Max
599
694
795
682
776
848
739
825
893
824
900
960
943
1011
1067
1115
1171
1220
1334
1379
1421
1589
1626
1661
319
378
439
335
394
452
348
407
463
375
432
486
397
452
505
432
484
535
506
558
611
596
651
705
113
Vent
Combined Appliance Input Rating in Thousands of Btu per Hour
Height
H
FAN FAN NAT FAN FAN NAT FAN FAN NAT FAN FAN NAT FAN FAN NAT FAN FAN NAT FAN FAN NAT FAN FAN NAT
(ft.)
6
8
10
15
20
30
50
100
+FAN +NAT +NAT +FAN +NAT+NAT +FAN +NAT +NAT +FAN +NAT +NAT +FAN +NAT +NAT +FAN +NAT+NAT+FAN +NAT +NAT +FAN +FAN +NAT
NA 74
25
NA 119 46
NA
178
71
NA
257
103
NA
351
143
NA
458 188 NA
582
246 1041
853 NA
NA 84
31
NA 138 56
NA
207
90
NA
299
131
NA
409
177
606
538 236 776
686
302 1226
1010 454
419 1513
1286 648
NA 80
NA NA
NA NA
28
36
41
NA NA
NA
NA NA
NA
NA NA
NA
NA 130 53
NA 152 67
NA NA 75
NA NA NA
NA NA NA
NA NA NA
NA
NA
NA
NA
NA
NA
193
82
233
106
270
137
250
NA
NA
122
NA
NA
NA
NA
NA
NA
NA
NA
279
334
368
404
119
152
172
198
NA NA
NA NA
NA
523
565
615
NA
NA
384
467
508
564
620
NA
163
212
243
278
328
348
NA
682
742
816
879
NA
501 218 724
611 283 874
668 325 955
747 381 1062
831 461 1165
NA 499 NA
636
781
858
969
278 1144
365 1374
496 1702
1089 606 1905
NA
669 2053
937
408
1156 546
1473 749
1692 922
1921 1058
139
2007 CALIFORNIA MECHANICAL CODE
Table 8-13
Table 8-13 Masonry Chimney with Two or More Appliances and Single-Wall Metal Connector [NFPA 54: Table 13.2(d)]
Number of Appliances:
Appliance Type:
Two or More
Category I
Appliance Vent Connection:
3
Vent Connector
Height Rise
H
R
FAN
(ft.)
6
8
10
15
20
30
50
100
(ft.)
1
2
3
1
2
3
1
2
3
1
2
3
1
2
3
1
2
3
1
2
3
1
2
3
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NAT FAN
21
28
34
21
28
34
22
29
34
23
30
34
23
30
35
24
31
35
24
31
35
NA NA 23
NA NA 30
NA NA 34
H
(ft)
6
8
10
15
20
30
50
100
140
12
5
NAT
NA
NA
NA
NA
NA
NA
NA
NA
97
NA
92
96
87
91
96
86
91
95
85
89
94
84
88
93
NA
NA
NA
NA
NA
NA
NA
NA
102
NA
103
112
99
111
119
108
119
127
113
123
131
39
52
61
40
52
62
41
53
62
43
54
63
45
55
64
47
57
65
50
60
68
104 49
115 59
124 67
19
6
7
8
Appliance Input Rating Limits in Thousands of Btu per Hour
FAN
Min Max Max Min
Common Vent Capacity
Vent
Height
Vent Connector Capacity
Single-Wall Metal Vent Connector Diameter — D (in.)
4
Min Max Max
Single-Wall Metal Connector
NA
NA
134
NA
137
143
130
136
143
129
135
141
128
134
140
126
132
138
124
130
136
Max
NAT
NA
NA
153
NA
139
156
151
150
166
151
170
185
167
185
199
187
203
216
204
218
231
122 200
127 215
133 228
FAN
Max Min
66
84
97
68
85
98
70
86
99
73
88
101
76
90
103
80
93
105
87
100
112
179
186
193
195
202
210
202
210
217
199
207
215
197
205
213
193
201
209
188
196
205
NAT
Max Max
191
227
258
208
240
264
225
255
277
271
295
315
303
325
343
347
366
381
392
408
422
89 182 410
102 190 425
115 199 438
100
123
142
103
125
145
106
128
147
112
132
151
117
136
154
124
142
160
139
158
176
151
169
188
FAN
Min
Max
243
253
262
617
636
654
231
239
247
250
258
266
267
276
284
268
277
286
265
274
282
259
269
277
252
262
271
271
321
365
298
343
376
316
358
389
376
411
439
425
455
481
492
518
540
567
588
607
NAT
Max
FAN
Min
Max
232 315
254 326
279 337
875
899
921
140
172
202
146
177
205
151
181
207
161
189
213
169
195
219
183
205
229
208
230
255
292
301
309
313
323
332
333
343
352
349
359
368
345
355
365
338
348
358
328
339
349
366
432
491
407
465
509
434
489
530
502
548
586
569
610
644
665
699
729
778
806
831
NAT
Max
200
231
269
207
238
274
213
244
279
225
256
289
235
266
298
250
282
312
287
320
351
328
361
392
9
FAN
Min
10
NAT
Max Max
FAN NAT
Min
362 474 252 499
373 557 299 509
381 634 348 519
387 530 263 529
397 607 309 540
407 663 356 551
410 571 273 558
420 640 317 569
430 694 363 580
445 646 291 623
456 706 334 634
466 755 378 646
439 734 306 614
450 787 348 627
461 831 391 639
430 864 330 600
442 908 372 613
452 946 412 626
417 1022 383 582
429 1058 425 596
440 1090 466 610
38
50
316
376
437
331
391
450
343
403
459
366
424
479
387
443
496
421
473
524
492
545
597
402 1181 444 560 1537 580
415 1210 488 575 1570 634
427 1238 529 589 1604 687
Minimum Internal Area of Masonry Chimney Flue (in.2)
28
Max Max
594
696
793
672
766
838
727
813
880
808
884
945
921
986
1042
1089
1145
1193
1302
1346
1386
63
Combined Appliance Input Rating in Thousands of Btu per Hour
78
113
FAN FAN NAT FAN FAN NAT FAN FAN NAT FAN FAN NAT FAN FAN NAT FAN FAN NAT FAN FAN NAT FAN FAN NAT
+FAN +NAT +NAT +FAN +NAT+NAT +FAN+NAT +NAT +FAN +NAT +NAT +FAN +NAT+NAT +FAN +NAT +NAT +FAN+NAT+NAT +FAN+FAN +NAT
NA
NA
25
NA 118 45
NA
NA
31
NA 136 56
NA
NA
NA
NA
NA
NA
NA
NA
28
36
NA
NA
NA
NA
NA
NA
NA
NA
NA 128 52
NA
NA
NA
176 71
190 81
205 89
NA
NA
NA
255
276
295
102
118
129
NA 348 142
NA
NA 405 175
NA
NA 380 162
NA NA 66
NA
230105
NA
335
150
NA 400 210
NA NA NA
NA
NA135
NA
398
195
NA 558 275
NA
NANA
NA NA 74
NA NA NA
NA NA NA
NA
NA
247120
NANA
NA
NA
NA
362
NA
NA
170
NA
NA
NA 503 240
NA 612 325
NA NA NA
NA
455
497
532
187
217
234
NA 579 245
NA 633 277
771
680 300
846 NA
1216 1000 450
677
602
280
866
808
739
377
1052 957 490
494
NA NA 663 2006 1885 1046
765
NA
NA
661
821
NA
321
456
947
772 360
NA
1136 928 405
849 415
1152 1076 600
1359 1139 540
1495 1264 640
1682 1447 740
1879 1672 910
CHIMNEYS AND VENTS
Table 8-14
Table 8-14 Single-Wall Metal Pipe or Type B Asbestos Cement Vent with Two or More Appliances [NFPA 54: Table 13.2(e)]
Number of Appliances:
Two or More
Appliance Type:
Draft Hood Equipped
Appliance Vent Connection:
Direct to Pipe or Vent
Vent Connector Capacity
Total vent Heigh
Connector
Rise
(ft.)
(ft.)
15
30
and up
4
21
28
34
23
30
35
25
31
36
40
53
61
44
56
64
49
58
68
5
6
7
8
68
86
98
77
92
102
84
97
107
102
124
147
117
134
155
129
145
164
146
178
204
179
194
216
190
211
232
205
235
275
240
265
298
270
295
321
Maximum Appliance Input Rating in Thousands of Btu per Hour
1
2
3
1
2
3
1
2
3
6-8
3
Vent Connector Diameter – D (in.)
Common Vent capacity
Total Vent Height
6
8
10
15
20
30
50
4
48
55
59
71
80
NA
NA
5
78
89
95
115
129
147
NA
Common Vent Diameter – D (in.)
6
111
128
136
168
186
215
NA
7
155
175
190
228
260
300
360
8
205
234
250
305
340
400
490
10
320
365
395
480
550
650
810
12
NA
505
560
690
790
940
1190
141
2007 CALIFORNIA MECHANICAL CODE
Table 8-15
Table 8-15 Exterior Masonry Chimney [NFPA 54: Table 13.2(f)]
Special Use:
Minimum Allowable Input Rating of Space-Heating Appliance in Thousands of Btu per Hour
Number of Appliances:
Single
Appliance Type:
Appliance Vent Connection:
Vent Height
(ft)
NAT
Type B Double-Wall Connector
Internal Area of Chimney (Square Inches)
28
38
50
63
37˚F or greater
6
8
10
15
20
30
50
12
19
0
0
0
NA
NA
NA
NA
0
0
0
0
NA
NA
NA
Local 99% winter design temperature: 37˚F or greater
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
123
190
249
184
0
NA
NA
NA
393
334
NA
NA
NA
NA
NA
0
0
0
0
0
0
579
6
8
10
15
20
30
50
0
0
0
NA
NA
NA
NA
0
0
51
NA
NA
NA
NA
68
82
97
NA
NA
NA
NA
116
127
141
NA
NA
NA
NA
156
167
183
233
NA
NA
NA
180
187
201
253
307
419
NA
212
214
225
274
330
445
NA
266
263
265
305
362
485
763
6
8
10
15
20
30
50
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
197
214
NA
NA
NA
NA
215
226
245
296
352
NA
NA
259
264
278
331
387
507
NA
349
352
358
398
457
581
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
312
331
393
450
NA
NA
416
423
430
485
547
682
972
27˚F to 36˚F
17˚F to 26˚F
5˚F to 16˚F
6
8
10
15
20
30
50
-10˚F to4˚F
6
8
10
15
20
30
50
–11˚F or Lower
142
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
Local 99% Winter Design Temperature: 27 to 36˚F
Local 99% Winter Design Temperature: 17 to 26˚F
Local 99% Winter Design Temperature: 5 to 16˚F
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
289
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
Local 99% Winter Design Temperature: –10 to 4˚F
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
78
NA
NA
NA
NA
NA
NA
NA
Local 99% Winter Design Temperature: –11˚F or Lower
Not recommended for any vent configuration
113
484
494
513
586
650
805
1003
CHIMNEYS AND VENTS
Table 8-16 – Table 8-17
Table 8-16 Exterior Masonry Chimney [NFPA 54: Table 13.2(f)]
Special Use:
Combined Appliance Maximum Input Rating in Thousands of Btu per Hour
Number of Applications:
Two or More
Appliance Type:
NAT + NAT
Appliance Vent Connection:
Type B Double-Wall Connector
Vent
Height
(ft)
12
6
8
10
15
20
30
50
100
25
28
31
NA
NA
NA
NA
NA
Internal Area of Chimneys (Square Inches)
19
46
53
56
67
NA
NA
NA
NA
28
71
82
90
106
NA
NA
NA
NA
38
50
103
119
131
152
NA
NA
NA
NA
143
163
177
212
NA
NA
NA
NA
63
188
218
236
283
325
NA
NA
NA
78
113
246
278
302
365
419
496
NA
NA
NA
408
454
546
648
749
922
NA
Table 8-17 Exterior Masonry Chimney [NFPA 54: Table 13.2(g)]
Special Use:
Combined Appliance Minimum Input Rating in Thousands of Btu per Hour
Number of Applications:
Two or More
Appliance Type:
NAT + NAT
Appliance Vent Connection:
Vent
Height
(ft)
37˚F or Greater
Type B Double-Wall Connector
Internal Area of Chimney (Square Inches)
12
19
6
8
10
15
20
30
50
100
0
0
0
NA
NA
NA
NA
NA
0
0
0
0
NA
NA
NA
NA
0
0
0
0
NA
NA
NA
NA
6
8
10
15
20
30
50
100
0
0
0
NA
NA
NA
NA
NA
0
0
51
NA
NA
NA
NA
NA
68
82
NA
NA
NA
NA
NA
NA
27˚F to 36˚F
28
38
50
Local 99% Winter Design Temperature:
37˚F or Greater
0
0
0
0
NA
NA
NA
NA
63
78
113
0
0
0
0
NA
NA
NA
NA
0
0
0
0
184
393
NA
NA
0
0
0
0
0
334
NA
NA
NA
0
0
0
0
0
579
NA
NA
NA
NA
NA
NA
NA
NA
NA
180
187
201
253
307
NA
NA
NA
212
214
225
274
330
445
NA
NA
NA
263
265
305
362
485
763
NA
Local 99% Winter Design Temperature:
27 to 36˚F
NA
NA
NA
NA
NA
NA
NA
NA
143
2007 CALIFORNIA MECHANICAL CODE
Table 8-17 continued – Table 8-18
Table 8-17 [NFPA 54: Table 13.2(g)] Continued
17˚F to 26˚F
Local 99% Winter Design Temperature:
6
8
10
15
20
30
50
100
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
6
8
10
15
20
30
50
100
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
5 to 16˚F
4˚F or Lower
17 to 26˚F
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
Local 99% Winter Design Temperature:
5 to 16˚F
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
264
278
331
387
NA
NA
NA
NA
352
358
398
457
581
862
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
430
485
547
682
NA
NA
Local 99% Winter Design Temperature:
4˚F or Lower
Not recommended for any vent configurations
Table 8-18 Exterior Masonry Chimney with Two or More Appliances, FAN + NAT [NFPA 54: Table 13.2(h)]
Special Use:
Combined Appliance Maximum Input Rating in Thousands of Btu per Hour
Number of Applications:
Two or More
Appliance Type:
FAN + NAT
Appliance Vent Connection:
Type B Double-Wall Connector
Vent
Height
H
(ft)
6
8
10
15
20
30
50
100
144
12
74
80
84
NA
NA
NA
NA
NA
19
119
130
138
152
NA
NA
NA
NA
28
178
193
207
233
250
NA
NA
NA
Internal Area of Chimney (Square Inches)
38
257
279
299
334
368
404
NA
NA
50
351
384
409
467
508
564
NA
NA
63
458
501
538
611
668
747
831
NA
78
582
636
686
781
858
969
1089
NA
113
853
937
1010
1156
1286
1473
1692
1921
CHIMNEYS AND VENTS
Table 8-19
Table 8-19 Exterior Masonry Chimney with Two or More Appliances, FAN + NAT [NFPA 54: Table 13.2(i)]
Special Use:
Minimum Allowable Input Rating of Space-Heating Appliance in Thousands of
Btu per Hour
Number of Applications:
Two or More
Appliance Type:
FAN + NAT
Appliance Vent Connection:
Type B Double-Wall Connector
Vent
Height
(ft)
Internal Area of Chimney (Square Inches)
12
19
6
8
10
15
20
30
50
100
0
0
0
NA
NA
NA
NA
NA
0
0
0
0
NA
NA
NA
NA
0
0
0
0
123
NA
NA
NA
6
8
10
15
20
30
50
100
0
0
0
NA
NA
NA
NA
NA
0
0
51
111
NA
NA
NA
NA
68
82
97
142
187
NA
NA
NA
37˚F or greater
27˚F to 36˚F
17˚F to 26˚F
28
38
50
63
78
113
0
0
0
0
249
398
NA
NA
0
0
0
0
184
393
714
NA
0
0
0
0
0
334
707
NA
0
0
0
0
0
0
579
1600
156
167
183
233
284
319
NA
NA
180
187
210
253
307
419
672
NA
212
214
225
274
330
445
705
NA
266
263
265
305
362
485
763
1554
182
197
214
263
316
429
NA
NA
215
226
245
296
352
470
723
NA
259
264
278
331
387
507
766
NA
349
352
358
398
457
581
862
1669
252
269
289
346
408
531
797
NA
301
312
331
393
450
580
853
NA
416
423
430
485
547
682
972
1833
296
320
339
404
468
603
NA
NA
349
371
397
457
528
667
955
NA
484
494
513
586
650
805
1003
NA
Local 99% Winter Design Temperature:
37˚F or Greater
0
0
0
0
190
334
NA
NA
Local 99% Winter Design Temperature:
27˚F to 36˚F
116
127
141
183
230
330
NA
NA
Local 99% Winter Design Temperature:
6
8
10
15
20
30
50
100
0
52
NA
NA
NA
NA
NA
NA
55
74
90
NA
NA
NA
NA
NA
6
8
10
15
20
30
50
100
NA
NA
NA
NA
NA
NA
NA
NA
78
94
111
NA
NA
NA
NA
NA
Local 99% Winter Design Temperature:
5 to 16˚F
121
166
214
135
182
230
149
198
250
193
247
305
NA
293
360
NA
377
450
NA
NA
NA
NA
NA
NA
6
8
10
15
20
30
50
100
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
145
159
175
NA
NA
NA
NA
NA
5˚F to 16˚F
-10˚F to 4˚F
-11˚F or Lower
99
111
125
167
212
NA
NA
NA
17˚F to 26˚F
141
154
169
212
258
362
NA
NA
Local 99% Winter Design Temperature:
–10˚F to 4˚F
196
213
231
283
333
NA
NA
NA
249
269
292
351
408
NA
NA
NA
Local 99% Winter Design Temperature:
–11˚F or Lower
Not recommended for any vent configurations
145
2007 CALIFORNIA MECHANICAL CODE
146