SECTION 15600
HVAC EQUIPMENT
PART ONE - GENERAL
1.01
DESCRIPTION
A. Provide and install air conditioning, heating and ventilating equipment as indicated on the
drawings and as specified herein.
B. All work specified in this Section is subject to the provisions of Section 15010.
PART TWO – PRODUCTS
2.01
ROOF MOUNTED A/C UNITS (Electric Cooling/ Gas Heat and Dehumidification Cycle)
A. Furnish and install complete factory assembled, piped, wired, tested and shipped in one piece
with single point power connection. Units shall meet or exceed cooling/heating capacities and
operational characteristics as scheduled on the Contract Documents and as specified herein.
B. Outside air system, filters, switches and all standard operating safety controls shall be furnished
and factory installed. Units shall be specifically designed for outdoor curb mounting.
C. Units shall have decals and tags to indicate caution areas and aid unit service. An electrical
diagram shall be attached to control panels. Installation and maintenance bulletins shall be
supplied with each unit. Units shall be approved by U.L., A.G.A. or ETL.
D. Unit cabinet shall be constructed from heavy-gauge galvanized steel with a baked acrylic enamel
finish. Unit shall be equipped with individually removable exterior panels and an electric
compartment hinged access panel with quick release fasteners. The unit base shall overhang the
roof curb for water run-off and shall have a formed recess that seats on the roof curb gasket to
provide a positive watertight seal.
E. All units shall be designed for bottom supply and return duct connections. Minimum 1-inch thick,
3 lb. density neoprene faced fiberglass insulation shall be permanently fastened to the cabinet
interior.
F. Each unit shall be furnished with a direct expansion refrigeration system including a factory
charge of R-410a, coils fabricated of aluminum fins bonded to seamless copper tubes, refrigerant
metering device and liquid line filter--drier compressors shall be heavy-duty reciprocating, full
hermetic type with internal overload protection, crankcase heaters and high and low pressure
controls. Units nominal 7.5 tons and larger shall be provided with a minimum of two separate
refrigeration circuits with face-split evaporator coil. First stage of cooling shall be the lower half of
the coil. Each compressor shall have its own completely independent refrigeration circuit to
provide standby capacity. Units shall be protected from short cycling by a factory installed timing
device that prevents compressor re-start for a period of five minutes. Low ambient operation to
0° degrees F shall be standard on all units. Units shall also contain an integral de-humidification
cycle as indicated in equipment schedule, with hot gas reheat coil to permit de-humidification
without additional cooling being added to space if room temperature setpoint is satisfied.
Compressor shall be warranted for 5 years.
G. Gas heating section shall be 1 or 2-stage, indirect fired, multiple module gas furnace with
automatic spark ignition, suitable for operation on natural gas. Furnace shall have a power forced
draft combustion system, with venter fan on inlet to heat exchanger, out of the hot gas air stream.
700 Hall HVAC Replacement for
HVAC Equipment
Southern Crescent Technical College
15600.1
11009
Controls shall include automatic combination gas valve and pressure regulator, combination fan
cycle control thermostat, centrifugal switches, high limit thermostat flame sensor and auto-relight
system.
H. Supply fan shall be forward curved, double inlet centrifugal type. All units shall be belt driven by a
permanently lubricated motor with inherent overload protection. The motor shall have a variable
pitch cleave and adjustable base for proper alignment and belt tension adjustment.
I.
Unit shall be shipped complete with galvanized steel filter racks. Panel filters shall be 2" thick
throw-away glass fiber, 35% efficient pleated type.
J.
All units shall be complete with a motorized 0-25% outside air damper. Assembly shall consist of
low leak outside air, damper, damper motor and an adjustable linkage. Damper motor shall be of
the 2-position spring return type to close the outside air damper when the unit is not in operation.
K. Each unit shall be wired and tested at the factory before shipment. Wiring shall comply with NEC
requirements and shall conform to all applicable U.L. standards. All wiring shall be number coded
per the electrical diagrams. All electrical components shall be labeled according to the electrical
diagram and be U.L. recognized. Each unit shall have a 24-volt control circuit transformer and
control circuit fuse. The supply fan motor shall have contactors and over-load protection. Main
control panels shall be of weatherproof construction with hinged access panels and quick-release
latches. A terminal board shall be provided for the low-voltage control wiring. Knockouts shall be
provided in the bottom of the main control panel for field wiring entrance.
L. Shop drawings of required curb dimensions, wall thickness, and configuration, weight of
equipment to be supported and corner weights shall be submitted. Any special requirements such
as clearance to combustibles, minimum heights above roofs, interior compartments, conduits, etc
shall also be submitted and coordinated with other trades.
M. Refrigerant shall be R-410a.
N. Accessories to be provided:
1. Factory furnished and wired firestats. Return air firestats shall be set at 135 degrees and
supply air firestats at 245 degrees wired so as to shut down the supply air fan if a fire exists.
Firestats shall be of the manual reset type.
2. Low ambient operation kit (25 degrees F).
3. Fully automatic economizer cycle for units 7.5 tons and larger including factory installed
controls with moisture eliminators and minimum position rheostat including dampers with
modulating controllers and spring return operators. Provide barometric relief including
exhaust dampers and exhaust hood.
4. All rooftop units shall be furnished with an internal factory mounted 120 Volt convenience
outlet, internally wired through the roof curb assembly. Outlet shall be powered separately
from the rooftop unit to allow continued operation when the unit disconnect is off.
5. Units shall contain an integral de-humidification cycle with hot gas reheat coil as indicated in
equipment schedule.
6. Unit shall be provided with dehumidification cycle, which consist of hot gas reheat coil. All
associated wiring, tubing, and valves shall be provided and factory installed. Refer to
rooftop unit schedule for units requiring dehumidification cycle.
7. Units shall be provided with through the base electrical option.
8. Provide units with hail guard covers over the condenser coils.
O. Refrigeration controls shall include a minimum high and low pressure control, compressor
winding thermostat and overload, lockout circuit with reset at the unit control panel, contactors for
condenser/evaporator fans and compressor, and control power transformer.
700 Hall HVAC Replacement for
Southern Crescent Technical College
11009
HVAC Equipment
15600.2
P. Condenser fans shall be direct driven propeller type using three phase motors designed for
vertical discharge of air.
Q. The evaporator fan shall be belt driven forward curved type with an adjustable sheave and motor
sized to meet the air flow and static pressure as scheduled on the drawings. Motor shall have
thermal overload protection and motor and fan bearings shall be permanently lubricated. Blower
wheel shall be statically and dynamically balanced. Motor shall be two speed with two speed
starter where available.
R. Units shall be as manufactured by Trane, Carrier, or Lennox.
S. Minimum EER for units nominal 6.25 tons to 10.0 tons shall be 11.2. Minimum EER for nominal
12.5 ton units shall be 11.0. Minimum SEER for units nominal 5.0 tons and less shall be 13.0.
T. A full perimeter roof curb shall be provided for each unit. Units shall include factory or custom
curb as required to provide a curb meeting the separate roof curb specifications outlined in this
section. Curbs shall be designed to meet or exceed the minimum required height between roof
surface and unit flashing as outlined in the project roofing bond. Curbs shall also include
pressure treated wood nailers.
U. Controls shall be interfaced and connected per 15900 HVAC Instrumentation and Controls. Unit
shall interface with Johnson Control’s provided controls. Connection shall be via BACnet
interface.
V. Unit Controls
1. Unit control panel shall be a U.L. or ETL listed assembly. Unit controls shall include factory
mounted and wired control panel with wiring terminals, motor starters with three phase
overloads, and 24V control relay to interlock with building system controls. Controls shall be
installed in an easily accessible panel within the unit, or through separate exterior, hinged
access panel with NEMA 3R rating, flush mounted within the unit casing.
2. Unit manufacturer shall provide factory DDC controller for all internal controls to meet the
sequence of operation. The factory DDC controller SHALL meet the BACnet Protocol
Specification and shall have the BACnet Testing Laboratories (BTL) Approval Symbol for
certification and compliance of the BACnet standard. The BACnet Testing Laboratories
(BTL) is an independent testing laboratory (BTL – BACnet Testing Laboratory) that provides
testing for products that have BACnet capability. Only products that have been tested and
meet the BTL’s requirements are eligible to receive a BTL listing and stamp of approval. It is
the sole responsibility of the unit manufacturer to provide a DDC controller meeting the
BACnet Protocol that has been tested and certified by the BTL for a complete integration to
meet the sequence of operation.
3. The following points are a minimum the BACnet controller shall provide for
Integration/Interoperability into the building’s NATIVE BACnet Control System to meet the
required sequence of operation.
a. Monitored Sensor Value - These points shall provide current/status values.
1. Outside Air Temp
2. DX Coil Temp
3. Discharge/Supply Air Temp
4. Discharge/Supply Air Humidity
5. Heat Exchanger Temp
6. Fan Status
7. Mode of Operation - (Heating, Cooling, Dehumidification, Fan Only)
700 Hall HVAC Replacement for
Southern Crescent Technical College
11009
HVAC Equipment
15600.3
b. Commandable Points – These points shall be fully commandable by the existing NATIVE
BACnet Control System to allow the factory BACnet Controller to meet the sequence of
operation.
1. Unit Start/Stop
2. Mode of Operation – (Heating, Cooling, Dehumidification, Fan Only)
3. Occupied/Unoccupied
4. Fan Start/Stop – Override Functionality strictly for maintenance capability.
5. Compressor Start/Stop – Override Functionality strictly for maintenance capability.
6. Electric Duct Heat Start/Stop – Override Functionality strictly for maintenance
capability.
2.02
CENTRIFUGAL ROOF FANS
A. Fans shall be one-piece waterproof aluminum housing enclosing motor and drive, aluminum
centrifugal fan and fan shroud. Shaft bearings shall be self-aligning, pillow block ball type.
Bearings not permanently sealed and lubricated shall have extended grease fittings.
B. An internal power wiring post shall extend from motor compartment through curb cap. Seal all
penetrations where wiring post penetrates housing and curb cap.
C. Accessories shall include backdraft damper, bird screen, disconnect switch, and motor thermal
overload protection. Motor and drive shall be mounted on vibration isolators.
D. Units shall be complete with motor starters. Refer to starter specification section 15900 for
additional requirements.
E. Manufacturers shall be Greenheck, Penn, Cook, Acme, or approved equal.
F. A full perimeter roof curb shall be provided for each unit. All curbs requirements shall be
furnished by the equipment supplier to the contractor for coordination and fabrication of the
appropriate curbs and supports.
2.03
CUSTOM ROOF MOUNTING CURBS
A. Provide a pre-fabricated internally insulated, min. 14 gauge galvanized steel roof mounting curb
for all roof mounted equipment. Duct support members shall be provided to allow for prehandling of ductwork prior to unit installation. Provide gasketing to form a positive, weather tight
seal between the curb and unit base. Design shall comply with all requirements of the National
Roofing Contractors Association. Base of curb shall conform to roof slope and provide a level
base on which to mount equipment. Coordinate roof curb location and flashing. Top of curb shall
be level. Equipment shall be mounted level on curb. Top of roof curb shall provide the minimum
clearance required between roof finished surface and curb top as required by roofing
manufacturer. Mechanical contractor shall coordinate exact curb height required with general
division of work.
B. Shop drawing of each curb shall submitted for review. Curb shop drawings shall be sealed by a
licensed engineer. Curbs shall meet all requirements noted on plan detail.
C. Insulation shall be 1-1/2 inch thick, 3-lb. density rigid type
D. Basis of design curbs are manufactured by MGM: Equals are: Custom Curbs, RPS, Plenums,
Inc., Micro Metals or Creative Metals.
2.04
EQUIPMENT LABELING
700 Hall HVAC Replacement for
Southern Crescent Technical College
11009
HVAC Equipment
15600.4
A. Each A/C unit, exhaust fans, starter, disconnect switch, etc., shall be labeled to indicate the unit
designation as indicated on the contract documents.
B. Labels shall be exposed to view on all equipment located above ceilings, in mechanical rooms or
exterior mounted. Labels shall be concealed on equipment located in finished areas.
C. Labels shall be 2" high black film adhesive backed letters.
2.05
MOTOR STARTERS AND CONTACTORS
A. Furnish individual automatic motor starters for all single and three phase motors, unless
specifically specified as part of equipment furnished in other specification sections. All starters
furnished under Division 15 of the contract shall comply with the following requirements.
B. Starters shall be furnished with individual phase thermal overload protection, and with two (2)
normally open auxiliary contacts, "Hand-Off-Auto" switch, 24 VAC coil, 24 VAC control
transformer, and pilot light.
C. Single phase fractional horsepower motors shall have internal thermal overload protection.
D. Three phase starters shall have internal loss of phase protection.
E. Interior starters shall be mounted in individual NEMA-1 enclosures or factory built starter panel.
All external starters shall have NEMA-4X rated enclosures for weatherproof operation. All
starters serving two-speed motors shall be designed for two speed duty.
F. Motor starters shall be manufactured by Furnas, Square D, Westinghouse, Siemens, or General
Electric.
G. Voltage for holding coils shall not exceed 120 volts. Provide built-in transformers with fuses.
Provide auxiliary contacts as required by control circuits.
H. Each starter shall be provided engraved laminated plastic nameplates describing the piece of
equipment being served.”
2.06
AIR FILTERS
A. Contractor shall be responsible for maintenance of all filters until the final inspection. Units shall
not be operated without air filters at any time. Filters shall not be allowed to be overloaded with
dust or dirt. Upon completion of each phase of construction, when equipment is turned over to
Owner for their use, throw-away filters shall be removed from each unit and replaced with new
metal filter frames with replaceable media as specified in this section. Provide and install a
minimum of twelve (12) months of filters for each unit. Metal filter frames and media shall be
in place at the final inspection.
2.07
ELECTRIC CEILING HEATERS
A. Provide heavy duty, ceiling mounted, forced air heater of the voltage as specified under the
electrical division of work. Units shall be installed and wired in accordance with the
manufacturer's recommendations and applicable national and local codes.
700 Hall HVAC Replacement for
Southern Crescent Technical College
11009
HVAC Equipment
15600.5
B. Heater shall be a lay-in ceiling design mounted in the horizontal position. Unit to contain vertical
down discharge designed to supply heated air at the floor with unit mounted at 10'-0" above floor.
C. Fan motor shall be permanently lubricated, totally enclosed, shaded pole type with impedance
protection. A protective shield shall surround the motor to separate return air from the supply air.
D. Heating element assemblies shall consist of two or three corrosion resistant steel sheathed
elements, mechanically bonded to common corrosion resistant steel fins. Elements shall be
helically coiled nickel chromium alloy resistance wire completely embedded in and surrounded by
magnesium oxide, enclosed and swaged into corrosion resistant steel sheaths. Elements shall
have no more than 60 watts per inch.
E. Heaters shall be equipped with a zero voltage reset thermal overload, which disconnects the
motor and elements should normal operating temperatures be exceeded. Provide with manual
reset.
F. Provide integral thermostat.
G. Unit shall be U.L. Listed and be manufactured by Markel, Raywall, Q'Mark, or approved
equivalent.
2.08
ROOF MOUNTED ENERGY RECOVERY UNITS
A. Energy recovery units shall be roof mounted units consisting of a weather-proof housing mounted
on a full roof curb and containing supply and exhaust blowers, enthalpy wheel heat exchanger,
cooling coil, compressor, hot gas reheat, filters and controls. Unit refrigerant shall be R-410a, R407c or R-134a. The unit shall be completely factory assembled, pre-wired and thoroughly leak
and safety control tested. After assembly, each unit shall be charged and run tested.
B. Units shall be U. L. or E. T. L. listed. Performance shall be rated in accordance with ARI 340.
Efficiency shall exceed ASHRAE 90.1.
C. The housing shall be double wall construction. Steel shall have G-90 galvanized coating. The
outer housing shall be 18 gauge. Bases shall be 16 gauge. Inner liner shall be 22 gauge
galvanized steel or aluminum.
D. Cabinet insulation shall have a minimum of 1" thick closed cell foam insulation with an R value of
3.5 or 2" thick fiberglass insulation with an R value of 12.5.
E. The housing shall have access doors on each side of the unit for access to fan motors and filters.
Access doors shall be double wall construction and shall have full length stainless steel piano
hinges and quarter turn cam operated latches. Doors shall have full perimeter gasketing and rain
break overhangs.
F. Fresh air inlet and exhaust outlet shall have rain hoods, bird screens outside the unit. Fresh air
inlet and exhaust shall have motor operated dampers inside the unit which shall open before the
fans start. Supply and exhaust duct connections shall be inside the roof curb. The roof curb shall
not be used as a plenum.
G. The unit shall be provided with integral return air motorized dampers to allow the unit to provide
space humidity override during the unoccupied mode. Dampers shall be low leakage, airfoil
design with extruded vinyl blade edge and jamb seals. The dampers will be rated for a maximum
leakage rate of less than one percent of nominal airflow at 1 inch water gauge. Blades shall
rotate on bronze sleeve bearings. The actuators shall be direct drive.
700 Hall HVAC Replacement for
Southern Crescent Technical College
11009
HVAC Equipment
15600.6
H. The design of the cabinet shall allow access to the compressor and electrical control panel
without impairing unit operation.
I.
Unit base pan shall be constructed of stainless steel or aluminum with welded joints and seams
and with water dams around all openings. Unit base plan shall be coated with viscous petroleum
distillate to a uniform 1/4" wet depth, air dried, and cured to form a solid protective layer to
eliminate corrosive oxidation.
J.
All exterior screws, nuts, bolts and washers shall be zinc or cadmium coated and withstand a
minimum of 1,000 hours Salt Spray Test per ASTM B11797.
K. The housing which is constructed of G90 galvanized steel shall be chemically treated with zinc
phosphate. All housings, either steel or aluminum shall be coated with 0.3 MIL polyurethane or
alkyd primer, then finished with 0.8 MIL polyester or acrylic urethane top coat. Finish shall meet
or exceed 1,000 hour Salt Spray Test per ASTM B11797.
L. Roof curbs shall be full perimeter type constructed of 18 gauge galvanized steel. Curb shall be a
minimum of 12" high, shall be internally insulated with 1.5" thick rigid fiberglass and shall have a
wood nailer. The unit housing shall be designed to hang over the roof curb to provide an integral
curb counter flashing and for positive positioning of the unit on the curb.
M. Supply and exhaust blowers shall be backward inclined airfoil type or forward curved centrifugal
type with adjustable V-belt drive for balancing the air flow. The complete blower and motor
assembly shall be mounted on vibration isolators. The blower wheel shall be mounted on a solid
steel shaft supported by sealed ball bearings. The sealed bearings on both the blower shaft and
motor shall be permanently lubricated.
N. Fixed plates heat exchangers shall factory installed where indicated on drawings. The heat
exchanger shall be a cross flow plate air-to-air type. The alternate layers of plate create two
ducts, one for supply air and one for exhaust air. The plates shall be in pure aluminum for its
characteristics of corrosion resistance, ease of manufacture, flame proof, durability and excellent
heat transfer properties. Minimum plate thickness shall be .008”, with positive and negative
stamping for spacing and turbulence. The plates shall be sealed at air entry and exit to avoid air
leakage and separate exhaust and supply air by proper seals. The plates shall be housed inside
a casing composed of corner profiles and side walls. The corners of the exchanger package shall
be cast and sealed into especially rigid aluminum extrusions in the casing with permanent elastic
non acetic silicon (or polyurethane sealing). The side walls shall be manufactured from
galvanized steel sheets and bolted to the aluminum extrusions. The fixed plate heat exchanger
assembly shall be tested in accordance to ARI1060 and to ASHRAE 84-91. Access for all four
sides of the heat exchanger shall be provided for cleaning and inspection. Floor drain shall be
provided beneath the exhaust and supply sides of the heat exchanger. Drain connections
protrude through the side of the unit. Note: Drain lines must be properly trapped and freeze
protected in field.
O. Refrigerant cooling coils, condenser coils and hot gas reheat coils shall be aluminum fin,
mechanically bonded to seamless copper tubing. Coils on units with two refrigerant circuits shall
be face split type.
P. Compressors shall be hermetic scroll type with crankcase heater. Units with compressor capacity
larger than five tons shall have two compressors and two refrigerant circuits. Refrigerant circuit
shall include accumulator, filter-dryer, sight-glass, dual gauge connections and thermal expansion
valve. Safety controls shall include high pressure switch, low pressure switch and non-recycle
timer. Head pressure shall be controlled by a variable frequency drive on the condenser fan. Hot
gas by-pass control shall be provided to maintain minimum suction temperature. Compressors
shall have a five year warranty.
700 Hall HVAC Replacement for
HVAC Equipment
Southern Crescent Technical College
15600.7
11009
Q. Hot gas reheat coil shall be controlled by an electronically controlled step motor type valve
positioned by the control system to maintain a constant leaving air temperature. On two
compressor units the reheat coil shall be connected to the lead compressor only when the lead
compressor can provide sufficient reheat.
R. Condensate pan shall be constructed of stainless steel and shall be sloped to drain as required
by ASHRAE 82-1989.
S. Filter racks shall be provided in both supply and exhaust air streams ahead of the coils and
enthalpy wheel. Filters shall be 2" thick, pleated type with an efficiency of 30%. Filters shall be
sized for a maximum of 500 fpm face velocity.
T. The energy recovery units shall be completely factory assembled and pre-wired with a single
point electrical power connection. A main disconnect switch and motor starters with 3 overloads
shall be factory mounted and wired in a weather-proof control panel. Each circuit shall be
separately fused. Power wiring shall enter the unit from below inside the curb.
U. Controls shall be factory installed and pre-wired with a BACnet interface. Temperature and
humidity sensors, CO2 sensor, fan static differential pressure switches and BACnet interface
control module shall be furnished. All controls shall be furnished by the unit manufacturer and
interfaced with Johnson Controls via BACnet. A terminal strip shall be provided for connection of
the EMS LAN and duct mounted smoke detectors.
V. The following points are a minimum the BACnet controller shall provide for
Integration/Interoperability into the building’s NATIVE BACnet Control System to meet the
required sequence of operation.
a. Monitored Sensor Value - These points shall provide current/status values.
1. Outside Air Temp
2. DX Coil Temp
3. Discharge/Supply Air Temp
4. Discharge/Supply Air Humidity
5. Heat Exchanger Temp
6. Exhaust Air Temp
7. Exhaust Air Humidity
8. Fan Status
9. Mode of Operation - (Heating, Cooling, Dehumidification, Fan Only)
10. By-Pass Damper - (Opened / Closed)
b. Commandable Points – These points shall be fully commandable by the BACnet Control
System to allow the factory BACnet Controller to meet the sequence of operation.
1. Unit Start/Stop
2. Mode of Operation – (Heating, Cooling, Dehumidification, Fan Only)
3. Occupied/Unoccupied
4. Fan Start/Stop – Override Functionality strictly for maintenance capability.
5. Compressor Start/Stop – Override Functionality strictly for maintenance capability.
6. Electric Duct Heat Start/Stop – Override Functionality strictly for maintenance
capability.
W. A wiring diagram for the EMS controls shall be furnished to the unit manufacturer by Johnson
Controls.
X. Energy recovery units shall be controlled as follows:
700 Hall HVAC Replacement for
Southern Crescent Technical College
11009
HVAC Equipment
15600.8
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
A control module shall be provided for each unit.
Each ERU unit shall be programmed to start and stop according to the
occupied/unoccupied schedule provided by the Owner. The units shall not run when the
building is unoccupied, except when building humidity sensors senses a humidity level
above the set point.
Supply and exhaust fans and enthalpy wheel in the ERU shall run continuously when the
ERU unit is running.
A temperature sensor and humidity sensor located in the exhaust air intake shall provide
temperature and humidity input signals to the control module.
A CO2 sensor located in the exhaust air intake shall provide an indication of the average
CO2 level of the space.
When the temperature of the exhaust air is above 75oF or the relative humidity of the
exhaust air is above 50% the unit compressor shall run in the cooing cycle.
A temperature sensor located in the supply air shall control the hot gas reheat coil to
maintain a minimum leaving air temperature of 70oF when the compressor(s) is running.
A temperature sensor and a humidity sensor in the outside air steam of the leaving side of
the enthalpy wheel shall provide temperature and humidity indication only.
A temperature sensor in the outside air stream on the leaving air side of the cooling coil
shall provide temperature indication only.
Duct mounted smoke detectors, installed in the supply air duct of the ERU shall shut down
the unit when smoke is present.
When the unit is in the unoccupied mode, the outside air damper and exhaust air damper
shall close and the return air damper shall open. Upon a signal that the space humidity
exceeds set point, the unit shall energize the supply fan, dx cooling, ad modulate the reheat
coils as necessary to maintain the relative humidity set point.
Y. The unit manufacturer shall provide factory start-up. The start-up report shall be included in the
close-out documents. A copy of the start-up report shall be sent to the engineer as soon as the
start-up is completed.
Z. Energy recovery units shall be of the size and capacity scheduled on the drawings and shall be
as manufactured by Addison or approved equal by Innovent, Seasons Four, Aaon or Venmar.
2.09
MAKE-UP AIR UNIT (Applies to Alternate No. 1)
A. Make-up air units shall be roof mounted units consisting of a weather-proof housing mounted on
a full roof curb and containing supply cooling coil, compressor, hot gas reheat, filters and controls.
The unit shall be completely factory assembled, pre-wired and thoroughly leak and safety control
tested. After assembly, each unit shall be charged and run tested.
B. Units shall be U. L. or E. T. L. listed. Performance shall be rated in accordance with ARI 340.
Efficiency shall exceed ASHRAE 90.1.
C. The housing shall be double wall construction. Steel shall have G-90 galvanized coating. The
outer housing shall be 18 gauge. Bases shall be 16 gauge. Inner liner shall be 22 gauge
galvanized steel or aluminum.
D. Cabinet insulation shall have a minimum of 1" thick closed cell foam insulation with an R value of
3.5 or 2" thick fiberglass insulation with an R value of 12.5.
E. The housing shall have access doors on each side of the unit for access to fan motors and filters.
Access doors shall be double wall construction and shall have full length stainless steel piano
hinges and quarter turn cam operated latches. Doors shall have full perimeter gasketing and rain
break overhangs.
700 Hall HVAC Replacement for
Southern Crescent Technical College
11009
HVAC Equipment
15600.9
F. Fresh air inlet shall have rain hoods, bird screens outside the unit. Fresh air inlet shall have
motor operated dampers inside the unit which shall open before the fans start. Supply duct
connections shall be inside the roof curb. The roof curb shall not be used as a plenum.
H. The design of the cabinet shall allow access to the compressor and electrical control panel
without impairing unit operation.
I.
Unit base pan shall be constructed of stainless steel or aluminum with welded joints and seams
and with water dams around all openings. Unit base plan shall be coated with viscous petroleum
distillate to a uniform 1/4" wet depth, air dried, and cured to form a solid protective layer to
eliminate corrosive oxidation.
J.
All exterior screws, nuts, bolts and washers shall be zinc or cadmium coated and withstand a
minimum of 1,000 hours Salt Spray Test per ASTM B11797.
K. The housing which is constructed of G90 galvanized steel shall be chemically treated with zinc
phosphate. All housings, either steel or aluminum shall be coated with 0.3 MIL polyurethane or
alkyd primer, then finished with 0.8 MIL polyester or acrylic urethane top coat. Finish shall meet
or exceed 1,000 hour Salt Spray Test per ASTM B11797.
L. Roof curbs shall be full perimeter type constructed of 18 gauge galvanized steel. Curb shall be a
minimum of 12" high, shall be internally insulated with 1.5" thick rigid fiberglass and shall have a
wood nailer. The unit housing shall be designed to hang over the roof curb to provide an integral
curb counter flashing and for positive positioning of the unit on the curb.
M. Supply blowers shall be backward inclined airfoil type or forward curved centrifugal type with
adjustable V-belt drive for balancing the air flow. The complete blower and motor assembly shall
be mounted on vibration isolators. The blower wheel shall be mounted on a solid steel shaft
supported by sealed ball bearings. The sealed bearings on both the blower shaft and motor shall
be permanently lubricated.
O. Refrigerant cooling coils, condenser coils and hot gas reheat coils shall be aluminum fin,
mechanically bonded to seamless copper tubing. Coils on units with two refrigerant circuits shall
be face split type.
P. Compressors shall be hermetic scroll type with crankcase heater. Units with compressor capacity
larger than five tons shall have two compressors and two refrigerant circuits. Refrigerant circuit
shall include accumulator, filter-dryer, sight-glass, dual gauge connections and thermal expansion
valve. Safety controls shall include high pressure switch, low pressure switch and non-recycle
timer. Head pressure shall be controlled by a variable frequency drive on the condenser fan. Hot
gas by-pass control shall be provided to maintain minimum suction temperature. Compressors
shall have a five year warranty.
Q. Units shall be equipped with variable frequency drives. VFDs shall be provided with metal
enclosure and shall be factory wired and tested. VFDs shall control evaporator motor speed to
maintain duct static pressure setpoint. VFD setpoints shall be field adjustable from 0" w.g. to 3.5"
w.g. Drives shall include the following features:
1. Full digital control
2. Insulated gate bi-polar transistors (IGBT) used to produce the output pulse width modulated
(PWM) waveform, allowing for quiet motor operation
3. Inverters shall be capable of operation at a frequency of 8 kHz, so that no acoustic noise is
produced by the motor
4. NEMA 1 metal enclosure for reduction of radio frequency interference
5. Self diagnostics
6. Personal lockout code for additional security
700 Hall HVAC Replacement for
HVAC Equipment
Southern Crescent Technical College
15600.10
11009
7.
8.
9.
10.
Critical frequency avoidance
RS232C/RS485 capability
Electronic thermal overload protection
DC link feature for harmonic reduction and improved power factor
R. Hot gas reheat coil shall be controlled by an electronically controlled step motor type valve
positioned by the control system to maintain a constant leaving air temperature. On two
compressor units the reheat coil shall be connected to the lead compressor only when the lead
compressor can provide sufficient reheat.
S. Condensate pan shall be constructed of stainless steel and shall be sloped to drain as required
by ASHRAE 82-1989.
T. Filter racks shall be provided in both supply air streams ahead of the coils. Filters shall be 2"
thick, pleated type with an efficiency of 30%. Filters shall be sized for a maximum of 500 fpm
face velocity.
U. The make-up air units shall be completely factory assembled and pre-wired with a single point
electrical power connection. A main disconnect switch and motor starters with 3 overloads
shall be factory mounted and wired in a weather-proof control panel. Each circuit shall be
separately fused. Power wiring shall enter the unit from below inside the curb.
V. Controls shall be factory installed and pre-wired with a BACnet interface. Temperature and
humidity sensors, CO2 sensor, fan static differential pressure switches and BACnet interface
control module shall be furnished. All controls shall be furnished by the unit manufacturer and
interfaced with Johnson Controls via BACnet. A terminal strip shall be provided for connection
of the EMS LAN and duct mounted smoke detectors.
W. The following points are a minimum the BACnet controller shall provide for
Integration/Interoperability into the building’s NATIVE BACnet Control System to meet the
required sequence of operation.
a. Monitored Sensor Value - These points shall provide current/status values.
1. Outside Air Temp
2. DX Coil Temp
3. Discharge/Supply Air Temp
4. Discharge/Supply Air Humidity
5. Heat Exchanger Temp
6. Fan Status
7. Mode of Operation - (Heating, Cooling, Dehumidification, Fan Only)
8. By-Pass Damper - (Opened / Closed)
b. Commandable Points – These points shall be fully commandable by the BACnet Control
System to allow the factory BACnet Controller to meet the sequence of operation.
1. Unit Start/Stop
2. Mode of Operation – (Heating, Cooling, Dehumidification, Fan Only)
3. Occupied/Unoccupied
4. Fan Start/Stop – Override Functionality strictly for maintenance capability.
5. Compressor Start/Stop – Override Functionality strictly for maintenance capability.
6. Electric Duct Heat Start/Stop – Override Functionality strictly for maintenance
capability.
X. A wiring diagram for the EMS controls shall be furnished to the unit manufacturer by Johnson
Controls.
700 Hall HVAC Replacement for
HVAC Equipment
Southern Crescent Technical College
15600.11
11009
Y. Make-up air units shall be controlled as follows:
1. A control module shall be provided for each unit.
2. Each MAU unit shall be programmed to be enabled and disabled according to the
occupied/unoccupied schedule provided by the Owner. The units shall not run when the
building is unoccupied.
3. A temperature sensor and humidity sensor located in the supply air stream prior to the reheat
coil, shall provide temperature and humidity input signals to the control module.
4. A temperature sensor located in the supply air duct downstream of the reheat coil shall
o
control the hot gas reheat coil to maintain a minimum leaving air temperature of 72 F when
the compressor(s) is running.
O
5. When the outside temperature is 53 F or less the gas heating section shall activate and shall
O
modulate to deliver 72 F supply air.
6. Duct mounted smoke detectors, installed in the supply air duct of the MAU shall shut down
the unit when smoke is present.
Z. The unit manufacturer shall provide factory start-up. The start-up report shall be included in the
close-out documents. A copy of the start-up report shall be sent to the engineer as soon as the
start-up is completed.
AA. Unit control safeties shall include solid-state compressor lockout to shut-off the compressors
during internal or external overload, low pressure alarm, freeze protection for evaporator coil, high
pressure, or loss-of-charge.
BB. Gas heating module shall have Gas Furnace per schedule. One furnace will be capable of 25% to
100% modulation and the other shall have single stage control. A programmable controller shall
be factory mounted, wired and programmed to control the modulation and stage furnaces to allow
for smooth modulation turn down to 12.5:1. Each furnace shall have a 3/4" gas connection.
Furnaces shall be constructed with a 409 stainless steel heat exchanger that shall have stainless
steel heat tubes, vest panel, collector box, flue duct assembly that is sealed and downward
sloping with a stainless steel safety grill conforming to ANSI Z83.8 that includes drainage for
snow and water. The flue outlet and combustion air intake are shall be located a minimum of 24"
above grade to prevent blockage by snow, water and vegetation debris exceeding the minimum
of 12" set by the National Fuel Gas Code. The furnace shall be capable of supply air temperature
raises from 25 to 90 degrees F. and shall be capable of -40 degree operation. Furnace shall be
accessed by a tool type latched and hinged service door as required by ANSI but not requiring
any further tool access beyond the latched access door. The furnace shall be equipped with
direct spark ignition using a control with diagnostic LED indicator for service. Service of furnace
shall not require the service personnel to lay or kneel on the deck surface that could damage roof
seal integrity. The furnace shall not have any sealing surfaces in contact with the flue products in
the supply air stream. Only mechanically fastened inlet and outlet joints of the heat exchanger
tubes shall acceptable in the air stream to ensure minimal flue gas leakage potential into the
supply air stream. The furnace collector box shall be outside the supply air stream and make
provision to drain any potential condensate. The gas furnace shall not be constructed of 300
series stainless steel, which is be susceptible to stress crack corrosion from 140º to 300. Gas
heat shall modulate to provide 72F delivery temperature.
CC. Make-up air units shall be of the size and capacity scheduled on the drawings and shall be as
manufactured by Addison or approved equal by Innovent, Seasons Four or Venmar.
2.10
POWERED INDUCTION TERMINAL UNITS
A. Terminals shall be series flow type. Terminals shall be certified under ARI Standard 880-94
certification program and carry the ARI seal.
700 Hall HVAC Replacement for
Southern Crescent Technical College
11009
HVAC Equipment
15600.12
B. Terminals shall be designed, built, and tested as a single unit including motor and fan assembly,
primary air damper assembly, electric heating coil, multi-point pressure sensor, filter track, filters
and accessories as specified. Each unit shall be shipped as a complete assembly. All electrical
components shall be U.L. listed and installed in accordance with the NEC. Unit electrical
connection shall be a single point. All electrical components, including low voltage controls, shall
be mounted in sheet metal enclosures. The entire terminal shall be ETL or U.L. listed as a
complete assembly.
C. The terminal casing shall be minimum 20 gauge galvanized steel, internally lined with dual
density glass fiber insulation complying with U.L. 181 and NFPA code 90A. Exposed edges of
insulation shall be coated with NFPA 90A approved sealant to prevent entrainment of fibers in the
airstream. Terminals shall have round primary duct collar and a rectangular discharge flanged
duct connection. Terminal casing shall be designed for hanging by sheet metal straps.
D. The terminal casing shall have a bottom access panel designed to allow removal of the fan and
servicing of the terminal without disturbing duct connections.
E. The fan shall be forward curved type constructed of steel with a dynamically balanced wheel and
direct drive motor. Fan motor shall be energy efficient design, permanent split capacitor type, with
integral thermal overload protection and permanently lubricated bearings, and shall be designed
for use with an SCR for fan speed adjustment.
F. Terminals shall utilize a manual SCR to set fan airflow. Speed control shall incorporate a
minimum voltage stop to ensure motor cannot operate in a stall mode.
G. Primary air damper assembly shall be heavy gauge steel with shaft rotating in self-lubricating
bearings. Shaft shall be clearly marked to indicate damper position. The damper shall include a
mechanical stop to prevent over-stroking and a synthetic seal to limit close-off leakage.
H. Terminals shall include electric resistance heating coils. Heaters shall be factory installed, U.L.
recognized resistance, open-type heaters. Heaters shall contain a disc-type automatic pilot duty
thermal primary cutout, and a manual reset load carrying thermal secondary device. Heater
element material shall be nickel-chromium. Terminal connections shall be plated steel with
ceramic insulators. Heater shall be wired into unit to provide a single point unit power connection.
I.
Approved manufacturers: Metalaire, Carrier, Trane, Titus and Enviro-Tec.
PART THREE - EXECUTION
3.01
GENERAL
A. All equipment shall be installed as shown on plans and in accordance with the manufacturer's
recommendations.
B. Contractor shall be responsible for maintenance of all filters until the final inspection. The units
shall not be operated without air filters at any time. Filters shall not be allowed to be overloaded
with dust or dirt.
C. Upon completion of the project and immediately prior to acceptance by the Owner, the units shall
be provided with clean filters. Provide a minimum of twelve (12) months of filters for each unit.
D. Provide factory start up on all major pieces of equipment, with letter of certification stating proper
installation is present for the following components:
700 Hall HVAC Replacement for
HVAC Equipment
Southern Crescent Technical College
15600.13
11009
1.
2.
3.
4.
Rooftop Units
PIUs
ERUs
MAUs
E. Start-up of all equipment, including rooftop unit, shall include the completion of the Owner’s startup cards for each piece of equipment. See accompanying card at the end of this section. All
work shall be by a Georgia State Class II HVAC Technician.
F. All equipment shall be thoroughly cleaned before placing in service after initial test runs before
Owner occupancy.
G. All equipment containing fans and/or compressors hung from roof structure shall be supported by
a minimum of four (4) spring vibration isolation hangers.
H. A/C Contractor shall make out start-up cards for all heat and cool units as per start up card
furnished below and shall furnish same before final.
700 Hall HVAC Replacement for
Southern Crescent Technical College
11009
HVAC Equipment
15600.14
A/C Contractor shall make out start-up cards for all heat and cool units as per start up card furnished
below and shall furnish same before final inspection for each phase of construction.
A/C CONTRACTOR’S START-UP CARD
Southern Crescent Technical College
School Name
Date:
HVAC Contractor
Technician Name
Ga. License No.
(Required)
RTU #
ERU#____________
MAU#____________
PIU #
A/C EQUIPMENT
Rated Volts Rated Amps COOLING
HEATING
Discharge Pressure
Suction Pressure
Return Air Temp.
Supply Air Temp.
GAS FIRED EQUIPMENT
(Boilers, etc.)
Unit #
Unit #
Actual Manifold Pressure:
Mfg. Rated Manifold Pressure:
Actual Stack Pressure
Rated Stack Pressure
Actual Volts
ELECTRIC HEAT
Rated Volts
Rated Amps
Actual Amps
END OF SECTION 15600
700 Hall HVAC Replacement for
Southern Crescent Technical College
11009
HVAC Equipment
15600.15