Land Use and Environmental Service Agency
(Code Enforcement)
Mechanical Q & A 2005
Attention: 3 Denotes a new question!
z Denotes a revised/revisited question.
June 2005
General:
1)
2)
(Q) Are service ladders (access) required on existing structures higher
than the current Code required 16 feet above grade?
(A) Not on an exact equipment replacement. Access requirements
would be those that were in place when the original job was
installed.
(Q) Does piping, duct, etc. installed in walls that will be finished at a later
date, have to meet the Code requirements now OR later when the walls
are completed.
(A) ALL mechanical installations shall meet the Code as they are
installed. Materials and devices installed in an open wall (rough),
marked for future completion, shall meet ALL the Code requirements
now.
2nd Quarter
3)
4)
5)
6)
7)3
(Q) May nylon duct strap be used to hang items other than flex or fibrous
duct?
(A) No!
(Q) Will the inspection department allow the setting of a gas meter without
an appliance installation?
(A) No!
(Q) What is the policy governing “future” gas outlets?
(A) Future Gas Policy:
• Future gas piping in fire places for appliances shall not be
connected to source until future appliance is installed.
• Future low pressure (7”) piping extended to future
appliance location shall be sized based on maximum
capacities and properly capped.
• Future 2lb piping extended to future appliance location
shall be sized based on maximum capacities, installed
pressure regulator and properly capped.
(Q) Would the bare liquid line of a AC line-set, touching a support strap
made if dissimilar material, require protection from galvanic action?
(A) Yes!
(Q) Is there anything in the Code that Governs the termination of exhaust
vents with reference to a gas meter?
(A) The Code does not govern or restrict gas meters!
Land Use and Environmental Service Agency
(Code Enforcement)
Mechanical Q & A 2005
Attention: 3 Denotes a new question!
z Denotes a revised/revisited question.
June 2005
Equipment:
1)
2)
3)
4)
(Q) Would the equipment accessibility requirements of the Code be met
when the only accessibility to a tenant’s piece of equipment is through the
space of another tenant?
(A) No! DOI and the ICC have determined that accessibility to
equipment shall be provided to “all” tenants, at any time. Due to the
security (alarms) of independent tenants and or bonding requirement
of their insurance companies, accessibility can not be assured at any
time. Therefore, roof access ladders/stairs shall be accessible from a
common stairwell or exterior ladder.
(Q) Does the condensate drain in an attic need to be insulated?
(A) No!
(Q) Where does condensing furnace condensate have to discharge?
(A) Same requirements as evaporator condensate unless
specifically required in appliance installation instructions.
(Q) Are drip legs required on pressure regulators?
(A) Not unless required to do so by the manufacturer.
2nd Quarter
5)3
(Q) Does the Code require an I ½ “ clearance all the way around the pan
when said pan is placed under equipment?
( A) No! The Code only requires that the pan be 3” larger the
equipment size. NCDOI has not published an interpretation that
would require the equipment centered within the pan.
Land Use and Environmental Service Agency
(Code Enforcement)
Mechanical Q & A 2005
Attention: 3 Denotes a new question!
z Denotes a revised/revisited question.
June 2005
Duct:
1)
2)
(Q) Does a stud cavity used as a return, have to be lined with metal?
(A) No!
(Q) Can flex duct insulation be stretched over the supply boots to meet
the insulation requirements?
(A) No! Not completely. The diameter of the flex duct is less than
that of the boot so additional insulation would have to be added to
completely cover the boot. The insulation should not be stretched to
the point where it is compressed resulting in an loss of the R value.
2nd Quarter
3)
4)
5)
6)
7)
8)3
(Q) Does the Code require access doors for duct detectors?
(A) Yes! Per 606.3
(Q) Would a 6” deep box be required when tapping a furnace housing
with round duct?
(A) No! Not unless a filter rack was installed with the tap.
(Q) What is the proper connection procedure for duct connector material
used as bath exhaust duct?
(A) The same as UL 181 flex duct installation (ADA) requirements.
(Q) Does the installation of duct smoke detectors require access panels?
(A) Yes! NFPA section 5.14.5.3 (referenced by the Code) states that
“ access doors or panels” shall be provided for cleaning.
(Q) What type of tape is required secure duct wrap (insulation)?
(A) DOI states the insulation wrap installed on metal duct shall be
secured with tape having a 25/50 smoke/flame spread rating.
(Q) Does a return have to be located 10 feet (10’) or more from an unvented fireplace?
(A) Yes! Section 918.6 (item 1) of the NC Mechanical Code states
that a return shall not be taken from the following locations:
1. Closer than 10 feet (3048 mm) from an appliance vent outlet, a vent
opening from a plumbing drainage system or the discharge outlet of
an exhaust fan, unless the outlet is 3 feet (914 mm) above the outside
air inlet.
Land Use and Environmental Service Agency
(Code Enforcement)
Mechanical Q & A 2005
Attention: 3 Denotes a new question!
z Denotes a revised/revisited question.
June 2005
Gas Pipe:
1)
2)
3)
4)
5)
6)
(Q) Where does the sediment trap have to installed?
(A) At the appliance down stream of the regulator (if applicable).
(Q) May the required shut for a residential range be installed behind the
appliance?
(A) Yes!
(Q) May galvanized pipe be used as gas piping?
(A) Yes!
(Q) Does galvanized gas pipe and fittings installed above grade, outside a
building, require painting?
(A) No!
(Q) May gas piping be installed in return ceiling plenums?
(A) Yes! Provided there are no unions or flare fittings in the gas line.
(Q) may pressure regulators be installed in return ceiling plenums?
(A) No! Pressure regulators, valves or fossil fuel appliances shall
not be installed in a return ceiling plenum.
2nd Quarter
7)
8)
9)
10)
(Q) The Code requires that a brass nipple (fitting) be installed between
copper and steel because they are dissimilar materials. May the copper
ftp adapter be soldered to the mpt brass nipple?
(A) No!
(Q) What is the proper burial depth when a gas line is protected?
(A) 12”! The code mentions an 8” burial depth for pipe not subject
to damage such as digging. Inspector’s call.
(Q) May flexible exterior pvc conduit be used to protect gas line (other
than steel) installed in the -3” to +36” area referenced by the DOI
interpretation?
(A) Yes! Flexible electrical type B conduit would serve as an
equivalent to protect a gas line from string trimmers.
(Q) Do the Track Pipe installation instructions allow the substitution of
flexible metal conduit for protection instead of a hardened striker plate?
(A) No! The manual speaks of flexible metal conduit in addition to
hardened striker plates in certain situations.
Land Use and Environmental Service Agency
(Code Enforcement)
Mechanical Q & A 2005
Attention: 3 Denotes a new question!
z Denotes a revised/revisited question.
June 2005
Exhaust/Flue:
1)
2)
3)
4)
(Q) May a flex duct connector be used for bath exhaust in a residence?
(A) Yes! Provided you don’t exceed a total of 14 feet of duct
connector.
(Q) What is the required slope requirement for horizontally installed type I
grease exhaust duct?
(A) The Code states:
506.3.8 Prevention of grease accumulation. Duct systems serving a
Type I hood shall be constructed and installed so that grease cannot
collect in any portion thereof, and the system shall slope not less than
one-fourth unit vertical in 12 units horizontal (2-percent slope) toward the
hood or toward an approved grease reservoir. Where horizontal ducts
exceed 75 feet (22 860 mm) in length, the slope shall be not less than one
unit vertical in 12 units horizontal (8.3-percent slope). Exhaust fans shall
be positioned so that the discharge will not impinge on the roof, other
equipment or appliances or parts of the structure. A vertical discharge fan
shall be manufactured with an approved drain outlet at the bottom of the
housing to permit drainage of grease to an approved grease reservoir.
(Q) What type of tape should be used on residential dryer exhaust?
(A) Any type of tape is sufficient.
(Q) May dryer exhaust be assembled with rivets?
(A) No! Rivets would be considered the same as a screw.
2nd Quarter
5)
6)
(Q) May PVC be used to vent down draft range hoods installed in
residences?
(A) Yes! See section 505.1 exception 2 for details.
(Q) When is fan assisted flue piping considered to be installed in a
horizontal position?
(A) Any portion of flue piping installed at an angle other than vertical
( ) is considered horizontal!