Carrier | WeatherExpert N9 | Specifications | Carrier WeatherExpert N9 Specifications

HVAC Guide Specifications — Section 48N2,N3,N4,N5,N6,N7,N8,N9
Packaged Rooftop Cooling Unit with Gas Heat and ComfortLink Controls
Size Range:
75 to 150 Tons, Nominal
Carrier Model Number:
48N2 (Vertical Supply/Return, Constant Volume [CV] Application, Staged Air Volume
[SAV™])
48N3 (Vertical Supply/Return, Variable Air Volume [VAV] Application)
48N4 (Horizontal Supply/Return, Constant Volume Application, Staged Air Volume)
48N5 (Horizontal Supply/Return, Variable Air Volume Application)
48N6 (Vertical Supply/Horizontal Return, Constant Volume Application, Staged Air Volume)
48N7(Vertical Supply/Horizontal Return, Variable Air Volume Application)
48N8 (Horizontal Supply/Vertical Return, Constant Volume Application, Staged Air Volume)
48N9 (Horizontal Supply/Vertical Return, Variable Air Volume Application)
Part 1 — General
1.01 SYSTEM DESCRIPTION
Outdoor, roof-curb mounted, electronically controlled heating and cooling unit utilizing hermetic scroll
compressors with crankcase heaters for cooling duty and gas combustion for heating duty. Units shall
supply air vertically or horizontally and return air vertically or horizontally as shown on the contract
drawings.
1.02 QUALITY ASSURANCE
A. Units shall be manufactured in a facility registered to ISO 9001 manufacturing quality standard.
B. Unit shall be rated in accordance with AHRI Standard 340/360, latest edition.
C. Unit shall be designed to conform to ANSI/ASHRAE 15 (latest edition), ASHRAE 62, and UL
Standard 1995.
D. Unit shall be listed by ETL and ETL, Canada, as a total package.
E. Unit shall be designed to conform to ANSI Standard Z21.47 (U.S.A.)/CSA Standard 2.3 (Canada),
Gas- Fired Central Furnaces.
F. Roof curb shall be designed to NRCA criteria per Guideline B-1986.
G. Insulation and adhesive shall meet NFPA 90A requirements for flame spread and smoke
generation.
1.03 DELIVERY, STORAGE, AND HANDLING
A. All units shall be completely shrink-wrapped from the factory for protection during shipment.
Tarping of units is unacceptable.
B. Inspect for transportation damage and store in clean dry place and protect from weather and
construction traffic. Handle carefully to avoid damage to components, enclosures, and finish.
Part 2 — Products
2.01 EQUIPMENT
A. Factory-assembled, single-piece heating and cooling unit. Contained within the unit enclosure
shall be all factory wiring, piping, refrigerant charge (R-410A), operating oil charge, dual
refrigerant circuits, microprocessor- based control system and associated hardware, and all
special features required prior to field start-up.
B. Unit Cabinet:
1. Unit shall be double-wall construction with insulation sealed between the inner and outer
panels. Panel assemblies shall not carry an R-value of less than 8. The panels shall be
galvanized steel (designated G60 per ASTM Standard A653 - minimum coating weight of 0.6
oz of zinc per square foot), bonderized and primer-coated on both sides and coated with a
baked polyester thermosetting powder coating finish on the outer surface.
2. Unit casing shall be capable of withstanding ASTM Standard B117 500-hour salt spray test.
3. Casing shall be watertight at –7 in. wg of internal pressure when tested per the UL 1995 rain
test requirements. Leakage rate shall be tested and documented on a routine basis on
random production units.
4. Sides shall have person-size hinged access doors for easy access to the control box and
other areas requiring servicing. Each door shall seal against a rubber gasket to prevent air
and water leakage. Access doors shall be one piece, double-wall construction with insulation
sealed between the inner and outer panels. Panel assemblies shall not carry an R-value of
less than 8. Access doors shall be equipped with tiebacks.
5. Side panels shall be easily removable for access to unit and shall seal against a full perimeter
automotive style gasket to ensure a tight seal.
6. Interior cabinet surfaces within heat exchanger section shall be lined with sheet metal on all
surfaces, insulated on the side opposite the airstream.
7. Insulation shall be applied by means of adhesion using a water reducible adhesive sprayed
onto interior surface. Adhesive shall maintain a satisfactory adhesion and cohesion within the
temperature range of –20 to 180 F and have excellent resistance to water and water vapor
when cured.
8. Unit shall contain a double sloped drain pan, to prevent standing water from accumulating.
Pan shall be fabricated of stainless steel. Unit shall contain a factory-installed nonferrous
main condensate drain connection.
9. Top cover of airside section to be sloped to prevent standing water.
10. Units shall be equipped with lifting lugs to facilitate overhead rigging. Lifting lugs shall also be
suitable as tie down points.
C. Compressors:
1. Fully hermetic scroll type compressors with overload protection and short cycle protection
with minimum on and off timers.
2. Factory rubber-in-shear mounted for vibration isolation.
3. Reverse rotation protection capability.
4. Crankcase heaters shall only be activated during compressor off mode.
D. Coils:
1. Evaporator Coil:
a. Intertwined circuiting constructed of aluminum fins mechanically bonded to seamless
copper tubes.
b. Full-face active type during full and part load conditions.
c. Coils shall be leak tested at 150 psig and pressure tested at 650 psig.
2. Condenser Coils:
a. Condenser coils shall be microchannel design. The coils shall have a series of flat tubes
containing a series of multiple, parallel flow microchannels layered between the
refrigerant manifolds. Microchannel coils shall consist of a two-pass arrangement. Coil
construction shall consist of aluminum alloys for the fins, tubes and manifolds.
b. Air-cooled condenser coils shall be leak tested at 150 psig and pressure tested at 650
psig.
E. Fans:
1. Supply Fan:
a. Unit shall have only one fan wheel, scroll, and motor.
b. Fan scroll, wheel, shaft, bearings, drive components and motor shall be mounted on a
formed steel assembly which shall be isolated from the unit outer casing with factoryinstalled 2-in. deflection spring isolators and vibration-absorbent fan discharge seal.
c. Fan shall be double-width, double-inlet, centrifugal belt driven airfoil type with single
outlet discharge.
d. Fan wheel shall be designed for continuous operation at the maximum rated fan speed
and motor horsepower.
e. Fan wheel and shaft shall be selected to operate at 25% below the first critical speed and
shall be statically and dynamically balanced as an assembly.
f. Fan shaft shall be solid steel, turned, ground and polished, and coated with rust
preventative oil.
g. Fan shaft bearings shall be self-aligning, pillow-block, re-greasable ball or roller-type
selected for a minimum average life of 200,000 hours at design operating conditions in
accordance with ANSI B3.15.
h. A single motor shall be mounted within the fan section casing on slide rails equipped with
adjusting screws. Motor shall be mounted on a horizontal flat surface and shall not be
supported by the fan or its structural members. Motor speed shall be controlled by a
variable frequency drive.
i. Fan drive shall be constant-speed fixed-pitch. All drives shall be factory-mounted, with
belts aligned and tensioned.
j. A high-static supply fan option shall be available.
2. Condenser Fans:
a. Direct-driven propeller type.
b. Discharge air vertically upward.
c. Protected by PVC-coated steel wire safety guards.
d. Statically and dynamically balanced.
e. Three-phase, totally enclosed motors.
F. Variable Frequency Drive:
All supply fan (and power exhaust fan and/or return fan motors, if equipped) shall be equipped
with variable frequency drive (VFD) inverter. The VFD shall be provided with a metal enclosure
and shall be factory- mounted, wired, and tested. The variable speed drive shall include the
following features:
1. Full digital control with direct control from the unit ComfortLink controls.
2. Insulated gate bi-polar transistors (IGBT) used to produce the output pulse width modulated
(PWM) waveform, allowing for quiet motor operation.
3. Inverters capable of operation at a frequency of 8 kHz so no acoustic noise shall be produced
by the motor.
4. VFDs shall include EMI/RFI (electromagnetic / radio frequency interference) filters.
5. Digital display keypad module, mounted on the VFD enclosure.
6. Local/Remote and Manual/Auto function keys on the keypad.
7. UL-listed electronic overload protection.
8. Critical frequency avoidance.
9. Self diagnostics.
10. On-board storage of unit manufacturer's customer user settings, retrievable from the keypad.
11. RS485 communications capability (accessory card source required).
12. Internal thermal overload protection.
13. 5% swinging (non-linear) chokes for harmonic reduction and improved power factor.
14. All printed circuit boards shall be conformal coated.
G. Outdoor-Air Hood Assembly:
Factory-installed motorized outdoor-air damper shall allow intake of up to 100% nominal airflow
(on units not equipped with optional economizer).
H. Heating Section:
1. Induced-draft combustion type with energy saving direct spark ignition systems and
redundant main gas valves.
2. The heat exchanger shall be of the tubular section type constructed of a minimum of 20-gage
steel coated with a nominal 1.4 mil aluminum-silicone alloy for corrosion resistance.
3. Burners shall be of the in-shot type constructed of aluminized steel.
4. Induced Draft Fans:
a. Direct-driven, single inlet, forward-curved centrifugal type.
b. Statically and dynamically balanced.
c. Made from steel with a corrosion-resistant finish.
5. High-corrosion areas such as flue gas collection and exhaust areas shall be lined with
corrosion-resistant material.
6. All gas piping shall enter the unit cabinet at a single location.
I. Refrigerant Components:
Unit shall be equipped with dual refrigerant circuits, each containing:
1. Filter drier.
2. Moisture indicating sight glass.
3. Two electronic expansion valves.
4. Fusible plug.
J.
Filter Section:
1. Mixed air filter section shall consist of 2-in. thick, MERV 7 disposable fiberglass filters of
commercially available sizes. Optional pleated, bag and cartridge filters shall be available.
(See special features section.)
2. Optional final filters with pre-filters shall be available. (See special features section.)
K. Controls, Safeties, and Diagnostics:
1. Controls:
a. Control shall be accomplished through the use of a factory-installed, microprocessorbased control system and associated electronic and electrical hardware. Control system
shall determine control sequences through monitoring the following operational variables:
1) Day and Time.
2) Schedule (Unoccupied/Occupied).
3) Set points (Unoccupied/Occupied, Economizer, Duct Pressure, others).
4) Space temperature.
5) Outdoor-air temperature.
6) Unit supply-air temperature.
7) Unit return-air temperature.
8) Supply-air fan status.
9) Economizer position.
10) Compressor suction and discharge pressure.
11) Navigator™ display.
12) Accessory and/or field-supplied sensors, function switches and/or signals.
b. Controls shall be capable of performing the following functions:
1) Capacity control based on supply-air temperature and compensated by rate of
change of return-air temperature (VAV) or room temperature (CV). Capacity control
shall be accomplished through the use of compressor staging or optional variable
output compressors.
2) Perform a quick test to check the status of all input and output signals to the control
system using the Navigator™ display.
3) Control of integrated economizer operation, based on unit supply-air temperature.
4) Supply fan volume control shall control output from a variable frequency drive to
maintain duct static pressure at user-configured set point (VAV). Static pressure reset
in conjunction with Carrier communicating terminals to reduce supply fan power
requirements. Control system calculates the amount of supply static pressure
reduction necessary to cause the most open damper in the system to open more
than the minimum value (60%) but not more than the maximum value (90% or
negligible static pressure drop).
5) Heating control shall provide space temperature control for unoccupied period
heating, morning warm-up sequence and occupied period heating (when configured).
Leaving air temperature control shall be provided when unit is equipped with
modulating gas heat option.
6) Adaptive optimal start shall determine the time unit will commence cooling (or heating
or heating for morning warm-up) during the unoccupied mode to ensure occupied
space reaches the set point in time for occupied mode.
7) Adaptive optimal stop shall turn off the compressors a preset amount of time before
the end of the occupied mode to conserve energy (CV only).
8) Alerts and Alarms: Control shall continuously monitor all sensor inputs and control
outputs to ensure safe and proper system operation. Alerts shall be generated
whenever sensor conditions have gone outside criteria for acceptability. Alarms shall
be initiated when unit control detects that a sensor input value is outside its valid
range (indicating a defective device or connection that prevents full unit operation) or
that an output has not functioned as expected or that a safety device has tripped.
Current alarms shall be maintained in STATUS function; up to 9 (current or reset)
shall be stored in HISTORY function for recall.
9) Timed override function shall permit a system in unoccupied mode to be returned to
occupied mode for a user-configured period of 1, 2, 3 or 4 hours by pressing the
override button on the front of the space temperature sensor.
10) Nighttime Free Cooling (NTFC) shall start the supply fan and open the economizer
on cool nights to pre-cool the building structure mass using only outdoor air. Function
shall be restricted to operation above a user-configured low lockout temperature set
point.
11) Modulating power exhaust control shall utilize a VFD to modulate capacity of exhaust
fan system. Capacity of exhaust air shall be modulated in response to building static
pressure at user-configured set point. Power exhaust fan operation shall be
interlocked with supply fan operation.
12) Return fan control (on optional return fan equipped units only) shall measure supply
fan cfm and shall utilize a VFD to modulate the return fan to maintain constant cfm
differential between supply and return fan. Return fan operation shall be interlocked
with supply fan operation. Capacity of exhaust air shall modulated in response to
building static pressure at user-configured set point.
13) Smoke control functions: Control shall initiate any of four separate smoke control
functions in response to closure of field switches. Functions shall include:
Pressurization, Evacuation, Smoke Purge and Fire Shutdown. Should two or more
switches be closed simultaneously, Fire Shutdown shall be initiated.
14) Support demand controlled ventilation through a reset of the economizer's minimum
position. This reset based on differential CO2 ppm (outdoor and indoor) can be
chosen as linear or as fast or slow-acting exponential curves.
15) Indoor air quality (IAQ) mode shall admit fresh outdoor air into the space whenever
space air quality sensors detect unsuitable space conditions, by overriding
economizer minimum damper position. IAQ shall be permitted only during occupied
periods, unless configured to be allowed during unoccupied periods also.
16) Provide control for reheat via auxiliary heating coil or gas heat during ventilation.
17) IAQ pre-occupancy purge function shall provide complete exchange of indoor air with
fresh air during unoccupied periods, when outdoor conditions permit. Function shall
energize supply fan and open economizer two hours before next occupied period;
duration of purge shall be user-configured (5 to 60 minutes).
18) Outdoor Air Control (OAC) function shall maintain a minimum quantity of outdoor
airflow into an occupied space. OAC mode shall be available only during an occupied
period. Outdoor airflow shall be monitored by an airflow station and transducer.
Economizer maximum damper opening position during OAC mode shall be userconfigured.
19) Dehumidification and Reheat: Dehumidification function shall override comfort
condition set points to deliver cooler air into the space and satisfy a user-configured
humidity set point at the space or return air humidity sensor. Reheat function shall
energize an auxiliary heating device should dehumidification operation result in
cooling of the space down to the occupied heating set point.
20) Supply Air Temperature Set Point Reset: Control shall automatically reset the unit
supply air temperature set point on VAV models from either space temperature or
return-air temperature, at user-configured rate and limit. Control shall also reset
supply air temperature set point via external 2 to 10 vdc signal representing 0° to 20
F range of reset. Control shall respond to higher of either reset if both are active.
21) Space Temperature Offset function shall permit occupants to adjust space
temperature set point by ±5° F using T-56 space sensor (equipped with sliding scale
adjuster).
22) Lead-lag function shall distribute starts between the two refrigeration circuits in an
effort to equalize the running time on the two circuits.
23) Condenser-fan cycling control shall maintain correct head pressure down to 32 F.
24) Refrigeration system pressures shall be monitored via pressure transducers. Alarms
for low pressure, high pressure will be permitted.
25) Timed Discrete Output function shall control an external function or device via userconfigured activity schedule. This schedule shall be separate and different from the
unit's occupied/unoccupied time schedule.
26) Humidifier control shall provide control for either LEN (local equipment network)
communicating control valve or discrete-type output, to maintain space humidity
conditions at user-configured set points.
27) Two-step demand limit control (when used in conjunction with CEM [controls
expansion module]).
28) Display in Metric units: Display may be configured to display data in Metric or English
(Imperial) units of measure.
2. Safeties:
Unit components shall be equipped with the following protections:
a. Compressors:
1) Overcurrent using calibrated circuit breakers (shuts down individual compressor).
2) Crankcase heaters.
3) High-pressure switch (shuts down individual circuit, automatic reset type).
4) Low-pressure monitoring (shuts down individual circuit, automatic reset type).
b. Check filter switch.
c. Belt-Drive Fan Motors:
Overcurrent protection manual reset circuit breakers.
d. Heating Section:
1) Redundant gas valves.
2) Flame proving controls.
3) Induced-draft fan motor speed sensor.
4) High-temperature limit switch.
5) Flame rollout switch.
3. Diagnostics and Prognostics:
a. The display shall be capable of indicating a safety lockout condition (alarm).
b. The display shall also be capable of indicating an alert condition which does not lock out
the unit, but informs the system monitor of a condition which could be detrimental to
either the unit or the comfort of the occupantsif allowed to continue.
c. Test mode must also be capable of displaying outputs of microprocessor-controller and to
verify operation of every thermistor, actuator motor, fan, and compressor before unit is
started.
4. Navigator™ Display Interface:
The Navigator display module shall be a portable hand-held display module with a minimum
of 4 lines and 20 characters per line, of clear English language. Display menus shall provide
clear language descriptions of all menu items, operating modes, configuration points and
alarm diagnostics. Reference to factory codes shall not be accepted. An industrial grade
coiled extension cord shall allow the display module to be moved around the chiller. Magnets
shall hold the display module to any sheet metal panel to allow hands-free operation. Display
module shall have NEMA 4x housing suitable for use in outdoor environments. Display shall
have back light and contrast adjustment for easy viewing in bright sunlight or night conditions.
The display module shall have raised surface buttons with positive tactile response.
L. Operating Characteristics:
1. Unit shall be capable of starting and running at 115 F (125 F for high-efficiency models)
ambient outdoor temperature per maximum load criteria of AHRI Standard 340/360, latest
edition.
2. Unit shall be capable of mechanical cooling operation down to 32 F ambient outdoor
temperature (–20 F with low ambient accessory).
3. Provides multi-stage cooling capability.
4. Provides 2 stages of heating capability.
M. Motors:
1. Compressor motors shall be cooled by suction gas passing over motor windings.
2. Condenser-fan motors shall be 3-phase, totally enclosed type with permanently lubricated
ball bearings and internal over-temperature protection.
3. Supply and exhaust fan motors shall be of the 3-phase, NEMA rated, open drip-proof (ODP),
ball bearing type, with efficiencies per EISA of 2007 (U.S.A.) requirements.
N. Electrical Requirements:
All unit power wiring shall enter unit cabinet at a single location.
O. Special Features:
1. Digital Compressor:
A digital compressor shall be available on the lead circuit for constant volume and variable air
volume configurations. The ComfortLink control system shall be capable of unloading this
compressor in an infinite number of steps from 100% of unit capacity down to 50% of
compressor capacity.
2. Humidi-MiZer® Adaptive Dehumidification:
The Humidi-MiZer dehumidification system shall be factory installed and shall provide greater
dehumidification of the occupied space by using two modes of dehumidification instead of the
normal design cooling mode of the unit:
a. Subcooling mode shall further sub-cool the hot liquid refrigerant leaving the condenser
coil when both temperature and humidity in the space are not satisfied.
b. Hot gas reheat mode shall mix a portion of the hot gas from the discharge of the
compressor with the hot liquid refrigerant leaving the condenser coil to create a twophase heat transfer in the system, resulting in a neutral leaving-air temperature.
c. The system shall be equipped with modulating control valves to provide precise leaving
air temperature control. On-off, cycling type control shall not be acceptable.
3. Condenser Coil Protective Coating - E-Coated Microchannel Coil:
E-coated aluminum microchannel coils shall have a flexible epoxy polymer coating uniformly
applied to all coil external surface areas without material bridging between fins or louvers.
Coating process shall ensure complete coil encapsulation, including all exposed fin edges. Ecoat thickness of 0.8 to 1.2 mil with top coat having a uniform dry thickness from 1.0 to 2.0
mil on all external coil surface areas, including fin edges, shall be provided. E-coated coils
shall have superior hardness characteristics of 2H per ASTM D3363-00 and cross-hatch
adhesion of 4B-5B per ASTM D3359-02. E-coated coils shall have superior impact resistance
with no cracking, chipping, or peeling per NSF/ANSI 51-2002 Method 10.2.
4. Condenser Coil Louvered Guard:
Louvered panels complete with support retainers and fasteners shall be provided for
protection of condenser coils.
5. Condenser Coil Grille Guard:
Welded wire grille complete with support retainers and fasteners shall be provided for
protection of condenser coils.
6. Low Outdoor Sound:
Low sound fans for outdoor sound reduction shall be available as a factory-installed option for
all units (except 90-ton high-efficiency, 105- ton, 120-ton high-efficiency, 130-ton highefficiency and 150-ton units).
7. Low Ambient Control:
a. Control shall regulate fan motor speed in response to the saturated condensing
temperature of the unit. The control shall be capable of operating with outdoor
temperatures at –20 F.
b. Motormaster® low ambient control shall be available as a factory-installed option or fieldinstalled accessory for all units.
8. Service Valves:
Shall be equipped with ball type service valves in the suction, discharge and liquid line for
each circuit.
9. Replaceable Core Filter Drier:
Shall be equipped with a replaceable core filter drier with isolation valves in each liquid line.
10. Hot Gas Bypass:
Unit shall be factory equipped with hot gas bypass valve and tubing to maintain capacity
control at minimal cooling loads.
11. Evaporator Coil Options:
12.
13.
14.
15.
a. Copper-fin coils shall be constructed of copper fins mechanically bonded to copper tubes
and copper tube sheets. Galvanized steel tube sheets shall not be acceptable. A polymer
strip shall prevent coil assembly from contacting the sheet metal coil pan to minimize
potential for galvanic corrosion between coil and pan. All copper construction shall
provide protection in moderate coastal environments.
b. E-coated aluminum-fin coils shall have a flexible epoxy polymer coating uniformly applied
to all coil surface areas without material bridging between fins. Coating process shall
ensure complete coil encapsulation. Color shall be high gloss black with gloss - 60 deg of
65 to 90% per ASTM D523-89. Uniform dry film thickness from 0.8 to 1.2 mil on all
surface areas including fin edges. Superior hardness characteristics of 2H per ASTM
D3363-92A and crosshatch adhesion of 4B-5B per ASTM D3359-93. Impact resistance
shall be up to 160 in./lb (ASTM D2794-93). Humidity and water immersion resistance
shall be up to minimum 1000 and 250 hours respectively (ASTM D2247-92 and ASTM
D870-92). Corrosion durability shall be confirmed through testing to be no less than 1000
hours salt spray per ASTM B117-90. Coil construction shall be aluminum fins
mechanically bonded to copper tubes.
Motorized Outdoor Air Damper:
a. Package consisting of dampers, actuator, and linkages in conjunction with control system
to provide outdoor air.
b. Dampers shall be an ultra low-leakage type with blade and edge seals. Dampers shall
exhibit a maximum leakage rate of 4 cfm per square foot of area at 1 in. wg pressure
differential when tested in accordance with AMCA Standard 500.
c. Dampers shall function as intended after 100,000 cycles when tested in accordance with
Section 8, UL standard 555S.
Ultra Low Leak Economizer:
Dry bulb, differential dry bulb temperature, enthalpy, or optional differential enthalpy
controlled integrated type consisting of dampers, actuator, and linkages in conjunction with
control system to provide primary cooling using outdoor air, enthalpy permitting,
supplemented with mechanical cooling when necessary.
a. Economizer shall meet the requirements of the California Energy commission airside
economizer acceptance test.
b. Dampers shall be an ultra low-leakage type with blade and edge seals. Dampers shall
exhibit a maximum leakage rate of 4 cfm per square foot of area at 1 in. wg pressure
differential when tested in accordance with AMCA Standard 500.
c. Dampers shall function as intended after 100,000 cycles when tested in accordance with
Section 8, UL standard 555S.
d. Actuator shall have a spring-return feature which shuts dampers upon a power
interruption or unit shutdown. Actuators are capable of internal diagnostics.
e. Equipped with a solid-state humidity sensor that is capable of sensing outdoor-air heat
content (temperature and humidity) and controlling economizer cut-in point at most
economical level. The user can also configure dew point limiting.
Modulating Power Exhaust with VFD:
Package shall include a double-width, double-inlet centrifugal belt drive, forward-curved
power exhaust fan with variable frequency drive control to maintain a field adjustable interior
space pressure set point.
a. Fan bearings shall be of the pillow block type with an average design life of 200,000
hours.
b. Fans shall be statically and dynamically balanced.
c. Installation:
1) Site installation shall require supply and installation of building pressure (BP) sensing
pick-up and tube to connect to BP transducer in unit.
2) All other wiring and pressure tubing shall be factory-supplied and factory-installed.
d. Bypass for the VFD shall be available as a factory-installed option.
e. A high-static power exhaust option shall be available.
Return Fan/Building Pressure Control:
a. Functions provided shall be:
16.
17.
18.
19.
20.
1) Airflow control for return duct path (dedicated to overcoming flow losses in return duct
system).
2) Modulate return airflow rate to track supply fan airflow rate and maintain a user set
delta cfm between the supply and return airflow.
3) Maintain building pressure by sensing building pressure and modulating fan motor
speed.
b. Option shall consist of following hardware:
1) Plenum fan assembly, with welded steel airfoil blade fan.
2) Spring isolation.
3) Belt-drive fan system, fixed pitch for maximum belt life and reliability.
4) Variable frequency drive (VFD) for return fan modulation control.
5) Supply air cfm and return air cfm sensors to measure supply and return airflow.
6) Exhaust damper with outlet hood.
7) Building pressure transducer.
c. Installation:
1) Site installation shall require supply and installation of building pressure (BP) sensing
pick-up and tube to connect to BP transducer in unit.
2) All other wiring and pressure tubing shall be factory-supplied and factory installed.
d. A high-static return fan option shall be available.
Extended Lube Lines:
Unit shall be equipped with extended lube lines to facilitate lubrication of fan bearings from
one side of the unit.
Belt Guard:
Unit shall be equipped with belt guard on all belt-driven fans. The guard shall completely
enclose the drive system and be removable for service.
Mixed Air Filters:
Unit shall be factory equipped with:
a. 4 in. MERV 8 pleated filters having the following characteristics: Efficiency of no less than
30% based on testing per ASHRAE Standard 52 and a minimum average arrestance of
95%.
b. 4 in. MERV 14 pleated filters having the following characteristics: Efficiency of no less
than 90% based on testing per ASHRAE Standard 52 and a minimum average
arrestance of >98%.
c. 12 in. MERV 14 bag filters having the following characteristics: Efficiency of no less than
90% based on testing per ASHRAE Standard 52 and a minimum average arrestance of
>98%. This option shall be available with 2 in. or 4 in. pre-filters.
d. 19 in. MERV 15 bag filters having the following characteristics: Efficiency of > 95% based
on testing per ASHRAE Standard 52. This option shall be available with 2 in. or 4 in. prefilters.
e. 12 in. MERV 14 cartridge filters having the following characteristics: Efficiency of no less
than 90% based on testing per ASHRAE Standard 52 and a minimum average
arrestance of >98%. This option shall be available with 2 in. or 4 in. pre-filters.
f. Field use filter section. The section shall be 4 ft in length and include 2 in. MERV 7
pleated filters.
Final Air Filters:
Unit shall be factory equipped with:
a. 12 in. MERV 14 cartridge filters having the following characteristics: Efficiency of no less
than 90% based on testing per ASHRAE Standard 52 and a minimum average
arrestance of >98%. This option shall be available with 2 in. or 4 in. pre-filters.
b. 19 in. MERV 15 bag filters having the following characteristics: Efficiency of > 95% based
on testing per ASHRAE Standard 52. This option shall be available with 2 in. or 4 in. prefilters.
c. 12 in. MERV 17 HEPA filter. This option shall be available with 2 in. or 4 in. pre-filters.
Totally Enclosed Fan Cooled (TEFC) Motors:
Unit shall be equipped with premium efficiency TEFC supply fan motor. Power exhaust or
return fan motor (if equipped) shall also be TEFC type.
21. VFD Bypass:
a. VFD Bypass shall be UL Listed by the drive manufacturer as a complete assembly and
carry a UL 508 label.
b. The VFD bypass shall be a complete factory-wired and tested bypass system consisting
of an output contactor and bypass contactor. Overload protection and shall be provided in
both drive and bypass modes.
c. The following operators shall be provided:
1) Drive mode selector.
2) Bypass mode selector.
d. When selector set to bypass, normally open contacts shall close to provide the bypass
status to the unit's control system. While in bypass mode, the control system shall
operate the supply fan using relay contacts to control the bypass contactor.
e. Motor overload protection shall be included.
22. Supply Fan Static Pressure Control (VAV Units):
Variable air volume units shall be equipped with a supply fan VFD. The VFD shall control
motor speed to maintain set point static pressure control at the supply duct sensor tube
location. The supply fan drive shall be field-adjustable to maintain supply duct static pressure
set point from 0.0-in. wg to 5-in. wg, adjusted via scrolling marquee display or Navigator™
display. A pressure transducer shall be factory-mounted and wired. (Control tubing from
sensor tube location to transducer shall be field-supplied and installed.) Transducer shall
provide a 4 to 20 mA signal to the unit control module; unit control module shall provide a 4 to
20 mA signal to the VFD indicating desired VFD output level.
23. Staged Air Volume (SAV) Units:
Staged air volume units shall be equipped with a supply fan VFD. The VFD shall control
motor speed to user configurable speeds. High speed shall be a percentage of 60 Hz, and
shall be user configurable. The range of adjustment for high speed shall be between 50 and
100% of 60 Hz. Low speed shall be a percentage of 60 Hz, and shall be user configurable.
The range of adjustment for low speed shall be between 33 and 67% of 60 Hz. The control
shall allow user-configurable fan speeds for cooling and heating modes.
24. Modulating Gas Heat:
a. Modulating gas heat option shall monitor unit supply-air temperature and control the unit
heat exchanger to provide the following sequences:
1) First-stage demand heating control, with modulation to maintain user-configured
heating supply air temperature set point. Turndown ratio to be at least 7:1 for the
smallest low heat option, ranging up to 18:1 for the high heat options.
2) Full-fire demand heating on heating control command.
3) Tempering heat control, based on user-configured ventilation supply air temperature
set point, to eliminate cold draft conditions with low mixed-air temperatures.
b. Modulating gas control option shall consist of:
1) Modulating controller capable of ensuring the proper fuel air mixture at operating
firing rates.
2) Supply-air temperature thermistors with duct-mounting base.
3) Limit switch temperature thermistor.
4) Stainless steel heat exchanger tubes.
c. Field installation shall be limited to installing three supply air temperature thermistors in
the supply duct. All other hardware, wiring and piping shall be factory-completed.
25. Stainless Steel Gas Heat Exchanger:
Heat exchanger shall be constructed of minimum 20-gage Type 409 Stainless Steel for
corrosion resistance. Tubing material shall be suited for high temperature and corrosion
resisting service. Tubing material shall comply with ASTM A268, Grade TP409. Tubing shall
be welded and annealed.
26. Blank section:
A 4 ft or 8 ft blank section shall be available for field installation of field-supplied devices.
27. Extended Chassis:
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Extended chassis designs shall contain an added length module, after the evaporator
section, as shown in the contract drawings. Module shall contain tracks to accept fieldsupplied and installed auxiliary heating coil.
Agion® Interior:
Interior panels shall be pre-coated with a silver zeolite antimicrobial material registered by the
US EPA for use in HVAC applications.
Split Unit:
The unit shall be available for shipment in two sections dependent upon the options selected.
UV-C Germicidal Lamps:
Emitters and fixtures for UV-C lamps shall be designed for use inside an HVAC system and
shall be covered by a 1-year warranty. Individual lamp output shall be measured in an ASME
nozzled test apparatus using a 45 F airstream moving at not less than 400 fpm. Lamp output
at 253.7 nm shall not be less than 10 μW/cm2 per inch of arc length measured at a distance
of one meter.
a. Power supplies for UV-C lamps shall be a high-efficiency electronic type which are
matched to the emitters and are capable of producing the specified output intensity with
an input power no more than 80 watts.
b. Fixtures for UV-C lamps shall be factory-installed and wired to a SPDT disconnect switch
and door interlock switches in each door. Fixtures are wired for 120 v/single phase
requiring a minimum circuit ampacity of 15 amps. Field power connections are made at
the switch box mounted on the exterior of the unit. Lamps shall ship separately for field
installation to minimize the chance for bulb damage.
c. Emitters and fixtures shall be installed in sufficient quantity and arranged so as to provide
an equal distribution of UV-C energy on the coil and drain pan.
d. The minimum UV-C energy striking the leading edge of the coil pan shall be not less than
820 μW/cm2 at the closest point and through placement, not less than 60% of that value
at the farthest point. Equal amounts are to strike the drain pan, either directly or indirectly
through reflection.
e. Emitters and fixtures shall be installed such that UV-C energy strikes all surfaces of the
coil, drain pan, and the available line of sight airstream.
Marine Lights:
Marine Lights shall be:
a. Cast, non-ferrous metal, weatherproof, fixture.
b. Cast, non-ferrous metal, weatherproof, electrical junction box.
c. Gasketed, heat and shock resistant glass globe protects against moisture and debris.
d. Cast, non-ferrous metal lamp guard to protect glass globe.
e. UL listed.
f. 100 watt type 'A' lamp maximum capacity.
g. Each fixture is equipped with a 75 watt, 130 volt, long life, vibration resistant, lamp
(8000+ hour typical lamp life), factory installed.
h. Metallic, single gang, electrical junction box, UL listed.
i. Factory-supplied and wired, SPST, UL listed toggle switch.
j. Each fixture is factory wired to an externally mounted switch box. (Field power
connections are made to the switch box mounted externally on the unit.)
k. All factory wiring penetrating through the panel is protected in 'RIGID' type metal conduit.
Non-Fused Disconnect:
A non-fused electrical disconnect for main unit power shall be factory installed. The
disconnect shall be an interlocking through-the-door type.
Fused Disconnect:
A fused electrical disconnect for main unit power shall be factory installed. The disconnect
shall be an interlocking through-the-door type.
115-Volt Convenience Outlet:
A duplex GFCI (ground fault circuit interrupt) receptacle shall be factory mounted in a
weatherproof enclosure and wired for a 10-amp load. It will remain powered when all unit
circuit breakers have been turned off. The outlet will be deenergized by the unit disconnect.
Phase/Voltage Monitor:
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Package shall include a device capable of detecting under/over voltage, phase loss or phase
shift. The device shall take action to protect the unit if an abnormal condition is detected.
Short Circuit Current Rating (SCCR):
An optional SCCR of 65 kA shall be provided for 460-volt units. An optional of 25 kA shall be
provided for 575-volt units.
Navigator™ Display Module Accessory:
The Navigator display module shall be a portable hand-held display module with a minimum
of 4 lines and 20 characters per line, of clear English language. Display menus shall provide
clear language descriptions of all menu items, operating modes, configuration points and
alarm diagnostics. Reference to factory codes shall not be accepted. An industrial grade
coiled extension cord shall allow the display module to be moved around the rooftop.
Magnets shall hold the display module to any sheet metal panel to allow hands-free
operation. Display module shall have NEMA 4x housing suitable for use in outdoor
environments. Display shall have back light and contrast adjustment for easy viewing in bright
sunlight or night conditions. The display module shall have raised surface buttons with
positive tactile response.
Controls Expansion Module (CEM):
Factory-installed package shall include all hardware for additional control of base unit
operation and product integrated controls features. The functions supported are:
a. Building pressurization, evacuation, and smoke purge control.
b. Supply air reset from external 4 to 20 mA signal.
c. Two-step demand limit inputs (when used with the CCN network).
d. Indoor air quality (IAQ) switch monitoring.
e. Outdoor airflow monitoring
f. Outdoor humidity monitoring.
g. Space humidity monitoring (required for dehumidification control, reheat and humidifier
control).
h. Return air humidity monitoring.
i. Demand limiting from an external 4 to 20 mA signal.
j. Static pressure reset from an external 4 to 20 mA signal.
k. Pre and post filter switch monitoring.
Relative Humidity Sensors:
Package shall contain either duct-mounted or wall-mounted sensors to measure the relative
humidity of the air within the occupied space (specify location) or return duct and/or outside
air.
NOTE: For relative humidity sensor monitoring, the CEM must also be ordered.
Indoor Air Quality (CO2) Sensor:
a. Shall have the ability to provide demand ventilation indoor-air quality (IAQ) control
through the economizer with an indoor air quality sensor.
b. The IAQ sensor shall be available in duct mount, wall mount, and wall mount with LED
display of CO2 in parts per million. The set point shall have adjustment capability.
Return Air Smoke Detector:
The smoke detector shall send input to the controller to shut down the unit in case smoke is
detected.
Airflow Sensor:
Airflow sensor package shall contain a airflow station with airflow sensor, a transducer and all
hardware required to measure the quantity of air. Optional economizer and CEM are required
with this option. Sensor package shall be available for outdoor air, supply air, and exhaust air
flows.
Differential Enthalpy Switch or Sensors (when equipped with both return air and outdoor air
humidity sensors):
a. For use with economizer only.
b. Capable of comparing heat content (temperature and humidity) of outdoor and return air
and controlling economizer cut-in point at the most economical level.
Phase/Voltage Monitor:
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Package shall include a device capable of detecting under/over voltage, phase loss or phase
shift. The device shall take action to protect the unit if an abnormal condition is detected.
BACnet Communication Option:
Shall provide factory-installed communication capability with a BACnet MS/TP network.
Allows integration with i-Vu® Open control system or a BACnet Building Automation System.
MODBUS Protocol Translator:
A controller-based accessory module shall provide CCN access to MODBUS Remote
Terminal Unit (RTU) protocol conversion.
LonWorks Protocol Translator:
A controller-based accessory module shall provide CCN access to LON FT-10A ANSI/EIA709.1 protocol conversion.
Space Temperature Sensor (T-56):
The T-56 space temperature sensor (for CV applications) shall monitor space temperature.
Device shall be suited for wall mounting in the occupied space. The T-56 sensor shall
incorporate a front-panel located slider switch to effect a remote change in set point of ±5° F.
The T-56 sensor shall also include a button used to initiate Unoccupied Override function.
Space Temperature Sensor (T-56) with CO2 Sensor:
This device shall incorporate interior space temperature sensing and interior space CO2 level
monitoring functions. Space temperature sensor shall sense the actual temperature in the
conditioned space via 10,000-ohm thermistor. Temperature set point adjustment
potentiometer via slide scale shall provide ±5° F adjustment. The CO2 sensor shall provide
CO2 measurement range of 0 to 2000 ppm. IAQ signal to unit base board terminals shall be 4
to 20 mA. Sensor shall be equipped with an override button for timed override. Sensor must
be powered by a separate field-supplied 24-v transformer.
Roof Curb:
Designed to comply with criteria established by NRCA Guideline B-1986. Formed 14-gage
galvanized steel with wood nailer strip as perimeter curb supporting the air-handling portion
of unit, and rail for supporting the condenser portion of the unit.
Roof Curb Condenser Section:
Formed 14-gage galvanized steel with wood nailer strip for supporting condenser section of
the unit to complete a full perimeter curb under entire unit.
Low Compressor Sound Blanket:
Low compressor sound blanket accessory shall be available for field installation.
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