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1.1
AIR HANDLING UNIT
Unit Construction
The following sections describe in detail construction requirements for the unit base, cabinet, access doors,
insulation and paint finish. Unit shall be built for outdoor installation.
Unit Base
Each unit shall be constructed on a base fabricated from ASTM A36 welded structural steel channel.
Tubular or formed metal channel bases are not acceptable. Channel bases shall be sized as a function of
air handling length as follows:
A.H. UNIT / LENGTH
MINIMUM / CHANNEL SIZE
UP to 10’
4” x 1-5/8”
(5.4lbs/Lin.Ft.)
11’ to 20’
6” x 2”
(8.2lbs/Lin.Ft.)
21’ to 30’
8” x 2-1/2”
(11.5lbs/Lin.Ft.)
41’ to 50’
12” x 3”
(20.7lbs/Lin.Ft.)
Heavy removable lifting lugs shall be added to the perimeter channel along the longest length of the unit.
The unit floor shall be fabricated of 16-gauge hot rolled galvanized steel sheets. (Other materials such as
aluminum, stainless and tread plates in various thickness are available.) The floor shall be supported by
structural and minimum 12-gauge formed galvanized steel members. Max spacing of floor support shall be
24” centers. These formed members shall be welded to other members for maximum strength. Floor skin
shall be supplied with standing seams design and drive cleats to maintain water and airtight seal. The
flooring shall be spot welded to the members below –no penetrations thru the floor skin shall be
acceptable. Welds shall be below the floor and spaced no greater than 6” on center.
Fans, coils and major components shall be supported with structural steel members.
Housing
The unit housing side and roof panels shall be constructed of 16-gauge galvanized steel, (other materials
such as aluminum, stainless and tread plates in various thickness are available.) and shall utilize a standing
seam modular panel type construction. The panels shall be caulked and attached to each other, to the
roof, and to the floor using nuts and bolts. Drive screw attachment is not acceptable. All panels shall be
removable. All seams shall be sealed with an acrylic latex sealant prior to assembling the panels and after
completion of the assembly. All floor openings shall have 12 gauge galvanized steel-framed flange around
the entire perimeter of opening for duct connection.
Minimum sound transmission loss (STL) through unit panels shall be as follows:
2” - 1½ PCF Insulation
125
250
25
29
4” – 3 PCF Insulation
26
36
500
36
1K
42
2K
47
4K
48
47
56
57
58
8K
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Hinged, double wall, insulated, man size access doors shall be provided in all sections requiring
access for maintenance or service. Access doors shall be fully gasketed with a closed cell,
replaceable neoprene gasket. The gasketing material shall be installed to allow for easy
removal and replacement. Access door must not leak more than 25 CFM @ 6” static pressure.
Submit test results from independent testing laboratory for engineer review.
Door hinges and latches shall be easily adjustable, without the use of shims or special tools, to
allow for a tight seal between the door and the doorframe as the gasketing material compresses
over time. The door hinge design shall allow for field modification of door swing and doors shall
be easily removable. Provide door detail drawing with submittal package.
Latches shall utilize phenolic knurled knobs. The latch assembly shall incorporate a built-in
safety catch to release cabinet operating pressure prior to opening the door.
Doors entering into any section of the air handler that contains rotating fans shall be provided
with zinc-plated nuts in lieu of knurled knobs. The nuts shall limit access to personnel with
proper tools. Include a 10” x 10” wire reinforced glass view window in each fan access door.
On ETL listed equipment, a door switch shall be interlocked with fan starter to stop the fan
before access door is opened.
Insulation
Insulation shall be 2” thick, 1½ lbs per cubic foot density, (other densities are available, 3.0 lbs/
ft3 and 6.0 lbs/ft3, 4” thickness is available) neoprene coated fiberglass to cover all walls, ceilings and under floors. Insulation shall meet NFPA-90A smoke and flame spread requirements.
There shall be no raw edges of insulation exposed to the airstream. Plenum fan sections shall
have a 20 gauge perforated galvanized sheet metal liner covering all wall and ceiling surfaces in
the blast area of fan.
Drain Pans
Drain pans shall be constructed from 16-gauge, 304 stainless steel. Galvanized steel drain pans
are not acceptable. The drain pan shall be insulated with 2.0”, 1½ # density insulation to prevent
condensation under the drain pan. Insulation shall be protected with an 18-gauge galvanized
steel liner. Drain pans must be sized such that the entire coil, including headers and return
bends, are inside the drain pan. Drain pans must slope in two directions so there is no standing
water in drain pan. Stainless steel condensate connection shall be provided on one side of the
unit. Coils shall be supported on 10 gauge stainless steel members to prevent immersion of the
coil in condensate and allow for complete cleaning of drain pan beneath the coils.
Paint Finish
After final assembly the unit exterior shall be coated with an industrial grade, high solids, and
polyurethane paint. In addition, all fan bases, springs and structural steel supports shall be
coated with the same finish. The paint system shall meet ASTM B117 Salt spray test for a minimum of 2000 hours in a 5% solution.
1.2
INTERNAL COMPONENTS
A. Fan Assembly
Plenum fan assemblies shall be arrangement one. Arrangement three plenum fans are not acceptable because they are less efficient and generate more noise. The air handling unit
manufacturer, for the purpose of sole source responsibility, shall manufacture all fan assemblies
including fan wheels supplied for the air handlers.
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Fan performance shall be based on tests run in an AMCA certified laboratory and administered
in accordance with AMCA Standard 210. Fan performance tests shall be taken with fans
running inside the cabinet to include any affects from the unit cabinet and other internal components. Fans shall bear AMCA seal for air and sound.
Plenum fans shall be configured so that both fan bearings are on the drive side of the wheel
with the wheel over hung (Arrangement #1). There shall be no obstructions (i.e., bearings or
bearing supports, etc.,) at the inlet of the fan. Fan wheel shall be aluminum with aluminum
extruded airfoil blades. Fan bearings shall have a minimum L10-200,000 Hr. operating life and
be mounted on a structural steel channel or machined surface. On DWDI fans the structure
supporting the bearing shall be fabricated from structural steel and be detachable to allow for
removal of the fan wheel and shaft as one piece. The fan discharge shall be isolated from the
cabinet by means of a neoprene-coated flexible connection. Plenum fans shall be provided with
spring-style thrust restraints.
Each fan shall be sized to perform as indicated on the equipment schedule. The wheel diameter shall not be less than that shown on the equipment schedule. The fan shall be constructed
to AMCA Standards for the Class Rating as indicated on the Equipment Schedule.
Provide grease fittings and extend lubrication lines to the motor side of the fan just inside the
access door.
B. Fan Base, Spring Isolation, and Support Framing
Mount fan and motor on an internal, fully welded, rigid steel base. Base shall be free-floating at
all four corners on spring type isolators with earthquake restraints. The fan assembly shall be
isolated from the cabinet by steel springs with minimum deflection of 2.0” or as indicated on
schedules. The spring isolators shall be mounted to structural steel members. All isolators shall
be rated for zone 4 seismic requirements. The spring isolators shall be mounted on a waffle pad
for vibration isolation.
C. Balancing
The fan shaft shall be sized not to exceed 75% of the first critical speed for maximum RPM of
Class specified. The critical speed will refer to the top of the speed range of the fans’ AMCA
class. The lateral static deflection shall not exceed 0.003” per foot of the length of the shaft.
Fans shall be balanced to ISO standard G6.3.
A copy of the above balance test data for this project showing calculations for deflection and
critical speed of the shaft and wheel assembly shall be submitted to the engineer and a copy
forwarded to the Owner.
D. Motors and Drive
Furnish premium-efficiency open drip proof, NEMA frame, ball bearing type motors. Reliance
“XE”, Century “E-Plus”, or Marathon “ZRI” with grease lubricated bearings and alemite fittings.
Horsepower’s as shown on the schedule are minimum allowable.
The motor shall be mounted on an adjustable slide rail motor base with two adjusting bolts per
side. The fan motors shall be factory wired to an external junction box with flexible conduit of
adequate length so that it will not have any affect on the vibration isolation.
Provide V-belt type, cast-iron sheaves, and reinforced rubber belts. The belts shall be selected
for 150% of the motor nameplate horsepower. Drives shall be “Browning” or equal
by “Woods.”
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E. Coils
Chilled water coils shall be of the plate fin extended surface type. Tubes shall be 5/8” outside diameter seamless copper with a 0.020” minimum wall thickness. Each coil shall have
individually replaceable return bends of 0.025 wall thickness on both sides of the coil. Coils incorporating a
“hairpin” type design are not acceptable. Tubes shall be expanded into the fin collars to provide a
permanent mechanical bond
The secondary surface shall be formed of 0.006” (.008, .010) aluminum (copper) fins and shall be
spaced not closer than 12 fins per inch with integral spacing collars that cover the tube surface.
Headers shall be non-ferrous seamless copper, outside the airstream and provided with brazed
copper male pipe connections. Drain and vent tubes shall be extended to the exterior of the air
handling unit.
All coils shall have counterflow construction with connections left or right hand as shown on the
drawings. The use of internal restrictive devices to obtain turbulent flow will not be accepted.
Cooling coil casings shall be of minimum 16-gauge, 304 stainless steel with double-formed
11/4” stacking flanges and 3/4” flanges on the side plates. All other coil casing shall be of
16gauge galvanized steel. Flanged tube sheets shall have extruded tube holes to prevent raw edges
of tube sheets cut into copper tubes because of thermal expansion of tubes in tube holes. Tube
holes with raw sheet metal edges are not acceptable. Reinforcing shall be
furnished so that
the unsupported length is not over 60”. All coil assemblies shall be tested under water at 300 psi
and rated for 150-psi working pressure. Headers are to be located inside the cabinet casing with
only the pipe connections extending through the casing. All sides of coils shall be carefully blanked
off to ensure all air passes through the coil.
Intermediate condensate pans are to be furnished on multiple coil units and single coils greater
than 48” high. The pans shall be 16Ga. 304 stainless steel and drain to the main drain pan through
copper downspouts.
All water coils shall be rated in accordance with ARI Standard 410.
The air handling unit manufacturer, for the purpose of sole source responsibility, shall
ture all coils supplied for the air handlers.
F.
manufac-
Filters
Filter sections shall be fabricated as part of the air-handling unit. Filters shall be arranged for upstream, downstream, or side loading as shown on the drawings. Provide filter-holding frames to
accommodate scheduled filters. Filter frames shall be 16 Ga. galvanized steel and shall be fully
welded to reduce leakage of air through corners.
Factory install at each filter bank a Dwyer Magnehelic “Series 2000” pressure gauge complete with
static pressure tips, hardware and fittings. Enclose the gauge in a protective sheet metal box with a
hinged inspection door. Paint to match unit.
G. Dampers and Louvers
Dampers shall be supplied with low leak extruded aluminum airfoil blades. Blades shall be supplied with rubber edge seals and stainless steel arc end seals. Rubber edge seals shall be backed
by the damper blade to assure a positive seal in the closed position. Dampers shall be provided
with nylon bearings within extruded openings. Damper leakage shall not exceed
6 CFM/ft2 at
5.0” of static pressure. Leakage testing shall be in accordance with AMCA
standard 500 figure
5.5. Test results must be from independent testing laboratory. Provide louvers for outside air and
exhaust air for units located outdoors. OSA Louvers shall be sized for a maximum face velocity of
500 fpm based on gross louver area. Louvers shall have zero water penetration at 600-ft/min air
velocities. )RUPRUHLQIRUPDWLRQ&$//
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Maximum louver pressure drop shall be 0.03” in w. g. at 500 ft/min. Provide test results from independent
testing laboratory. Test must be conducted in accordance to AMCA Standard 500 figure 5.5. Louver
water carry over must be less than 0.01 oz/ft2 at 1100 ft/min of free louver area. Test must be conducted
by independent testing laboratory per AMCA 500-89 figure 5.6. Hoods in lieu of louvers are not
acceptable.
H. Economizer / Mixing Box
Economizer section shall include dampers for return air, fresh air and exhaust air. Dampers shall be
opposed blade type. Dampers shall be sized for not greater than 1200 fpm face velocity based upon gross
damper area. Dampers shall meet above specifications. Furnish full height 24” wide access doors for
damper and linkage service.
I.
Air Flow Measuring Stations
Fans shall be supplied with a complete flow measuring system capable of supplying a 4 – 20mA. Output
signal to the EMS system that is proportional to airflow. The flow measuring station and a flow transmitter
shall be factory mounted. The flow measuring station shall consist of pressure taps pick-ups located in the
inlet cone of each fan. There shall be no obstruction created on the inlet of the fan by installation of flow
measuring device. Flow measuring stations installed in the inlet of fan will obstruct the fan inlet and will
decrease fan efficiency and increase sound power levels.
Provide a gauge with CFM scale on external side of the fan sections, which indicates the fan volume.
The electronic flow transmitter shall be mounted on the exterior of the fan section. It shall be capable of
receiving signals of total and static pressure from a flow element, of amplifying, extracting the square root,
and scaling to produce a 4 - 20 mA or 0 - 5 VDC output signal linear and scaled to air volume or velocity.
The flow transmitter shall be capable of the following performance and application criteria.
Calibrated spans from 0 - 896 FPM, in eight flow range increments. Output signal 4 -20 mA or 0-5 VDC
standard. Integral zeroing means 3-way zeroing valve with manual switch. Temperature effect ± 2.0% of
full span from 40° to 120°F.
The transmitter shall not be damaged by over-pressurization up to 200 times greater than span, and shall
be furnished with a factory calibrated span and integral zeroing means. The transmitter shall be housed in
a NEMA 12 enclosure with external signal tubing, power, and output signal connections.
The electronic differential pressure transmitter shall be Setra Model 264 or equal.
J.
Electrical Requirements:
Provide single source power panels (SSPP’s) that are constructed according to N.E.C. regulations and
carry a U.L.508 listing. The panel shall include a non-fused main disconnect switch, starters, transformer,
Hand–Off–Auto switches, relays and pilot lights for complete operation of the unit. The single source
power panels shall be factory wired to all factory furnished devices such as motors and interlocks.
The air handling unit manufacturer, for the purpose of sole source responsibility, shall manufacture all
electrical panel assemblies supplied for the air handlers. The air handling unit manufacturer shall be a U.L.
508 listed panel shop.
The main control panel shall have access door (s) for direct access to the controls. The panel shall be
NEMA type 3R (rainproof) and shall contain a single externally operated, non-fused disconnect, suitable
for copper wire up to and including 3” conduit. The electrical contractor shall bring separate 460/3/60
power to the single source power panel.
Provide vapor tight marine lights in each access section, factory wired to a single weatherproof
switch located on exterior of cabinet. Provide weatherproof, 15 amps, GFIC receptacle near the
light switch wired to the lighting circuit. The Electrical Contractor shall bring separate 120/1/60
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All wiring shall be run in EMT conduit, raceways are not acceptable.
If the unit requires splits, junction boxes shall be furnished on each section to allow the electrical
contractor to make final connections in the field. Wiring shall be clearly labeled to allow ease in final
interconnections.
K. Variable Frequency Drive
A single manufacturer of both motors and drives shall provide, coordinate and start-up a variable
speed drive system to ensure proper application of equipment to the driven load. The variable
frequency drive and motor shall be manufactured by Reliance Electric Company.
Motor and VFD shall be of the same manufacturer for single source responsibility. Factory warranty for
a period of at least three (3) years from date of start-up shall apply for both motor and drive.
VFD shall be current rated at 8 kHz carrier frequencies for VFD's 1-75 HP and 4 kHz for VFD's
100
-400 HP. All HP ratings shall meet or exceed Table 430-150 of the National Electric Code. Three
phase motor full load currents, HP, maximum current, and rated voltage shall appear on the drive
nameplate. No derating of the VFD shall be required due to increasing the switching frequency for
motor noise reduction. All drives designed at greater than 8 kHz carrier frequency (regardless of kHz
rating level of VFD) shall include an output voltage rise time reduction device as part of the VFD.
CODES/STANDARDS
VFD and options shall be ULTM 508 listed.
NEMA 12 enclosed VFD shall be ULTM approved for mounting in conditioned air ducts and plenums.
The drive and options shall comply with the applicable requirement of the latest standards of ANSI,
NEMA, National Electric Code NEC, NEPU-70, IEEE 519-1992, FCC Part 15 Subpart J, and CE96.
QUALITY ASSURANCE
Each drive shall be subjected to the following test and quality control procedures.
Every VFD shall be functionally tested under motor load. During this load test the VFD shall be
monitored for correct phase current, phase voltages, and motor speed. Correct current limit operation
shall be verified by simulating a motor overload.
Verification of proper factory presets by scrolling through all parameters shall be performed to ensure
proper microprocessor settings. The computer port should also verify that the proper factory settings
are loaded correctly in the drive.
All options shall be functionally tested including operation of a motor in the bypass mode if supplied.
Proper heater coil installation in motor overload, if supplied, shall be verified.
SERVICE
The VFD manufacturer shall maintain and staff worldwide service centers. The manufacturers shall
have the ability to test both the drives and motors in these service centers.
Start-up shall be included for each VFD provided.
Service engineers shall be employed by the manufacturer or be certified by the manufacturer and provide start-up service including physical inspection of drive and connected wiring and final adjustments
to meet specified performance requirements.
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DRIVE FUNCTIONS
The VFD shall have the following basic features:
An electronic overload circuit designed to protect an A-C motor operated by the VFD output from extended
overload operation on an inverse time basis. This electronic overload shall be ULTM and NEC recognized
as adequate motor protection. No additional hardware such as motor overload relays or motor thermostats
shall be required.
An LED display mounted on the door of the cabinet that digitally indicates:
•
•
•
•
•
•
•
•
Frequency output
Voltage output
Current output
Motor RPM
Input kW
Elapsed time
Time stamped fault indication
DC Bus volts
The VFD shall have the capability of riding through power dips up to 10 seconds without a controller trip
depending on load and operating condition. In this extended ride through, the drive shall use the energy
generated by the rotating fan as a power source for all electronic circuits.
RS232 Port and Windows TM based software for configuration, control and monitoring.
An isolated 0-20mA, 4-20mA or 0-4, 0-8, 0-10, volt analog speed input follower.
An isolated 0-10 volt or 4-20mA output signal proportional to speed or load.
PROTECTIVE CIRCUITS AND FEATURES
The VFD shall include the following protective circuits and features:
• Motor current exceeds 200% of drive continuous current rating.
• Output phase-to-phase short circuit condition.
• Total ground fault under any operating condition.
• High input line voltage.
• Low input line voltage
• Loss of input or output phase.
• External fault (this protective circuit shall permit wiring of remote N.C. safety contact to
shutdown the drive). User supplied end switches, thermal switches; fire stats, freeze
stats inputs will be connected to this VFD supplied circuit.
•
Metal oxide varistors for surge suppression shall be provided at the VFD LQSXWWHUPLQDOV
Complete contactor bypass shall be provided to allow motor to be safely transferred from VFD output to the
A-C line, or from the A-C line to the VFD, while the motor is at zero speed. The contactor bypass shall
utilize two motor contactors electrically interlocked. One contactor is to open and close the connection
between the VFD output and the motor. The other contactor will open and close the connection between
the bypass power line and the motor, providing "across the line" starting. Motor protection is to
be provided in the "bypass" mode by a bi-metallic Class 20 Smart Motor Protection adjustable
overload relay. Relay control logic shall also be included within the VFD enclosure to allow the
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operate the motor in either mode. The relay logic shall be 115 volts. The bypass circuit shall include a
second disconnect installed in the VFD to provide the ability to safely troubleshoot and test the controller,
both energized and de-energized, while the motor is running in the "bypass" mode. A contact closure shall
be provided to indicate that the drive is in the "bypass" mode. A remove/local selector switch shall also be
provided to transfer control from the keypad to user wired signals. Form "C" normally open and normally
closed contacts shall be provided for both run and IET/drive stopped. The entire bypass option shall be
packaged with the controller enclosure and be mechanically isolated from the VFD.
Input line fuses shall provide protection for the input rectification circuit using Class J fuses with interrupting
rating of 200,000 AIC. The series interrupting rating of the VFD and fuses shall be a minimum of 30,000
AIC and shall be stated in the VFD instruction manual as required by UL.
A main input disconnect shall mount within the standard NEMA 1 or NEMA 12 enclosure for positive power
disconnect of the VFD. It shall have the capability for door padlocking.
A three phase 3% impedance input line reactor shall be provided to minimize drive harmonics on an A-C
line and protect the drive from damaging electrical system transients.
Johnson Controls MetasysTM option card allows direct connection from the VFD to the Johnson N2 bus architecture. All configuration and control functions can be accessed through this card. Allows direct
communication between the VFD microprocessor and the host Johnson system. Fault diagnostics,
start/stop, speed commands, and all drive feedbacks shall be available over a single RS485
communication connection. Discrete signals such as bypass run or interlock open shall also be mapped
through the drive terminal strip to the MetasysTM system. The card shall have the ability to be used in a
"monitor only" mode where control shall be from an AHU or similar type controller directly wired to the drive.
L.
Unit Mounted Controls
All controls shall be factory mounted by the Air Handling Unit manufacturer. These controls shall include all
damper actuators, temperature sensors, pressure sensors, and airflow measuring sensors, filter switches,
smoke and fire detectors as indicated on the control drawings.
Electric and electronic controls shall be wired to a terminal block in a sheet metal enclosure located at a
common location mounted on the air-handling unit. All pressure sensing controls shall be piped to a common point on the unit with 1/4” compression fittings.
All controls shall be supplied by the temperature controls contractor and shipped to the Air Handling Unit
Manufacturer for installation.
M. Unit piping
All chilled water and hot water control valves shall be factory mounted by the Air Handling Unit
manufacturer.
In addition, all necessary piping specialties including strainers, shut-off valves,
thermometers, pressure taps, air vents, etc. shall be included as indicated on the piping diagram. Control
valve wiring (electric) or control tubing (pneumatic) shall be extended to a common point on the Air
Handling Unit.
N.
Sound Power and Performance Certification
The manufacturer shall perform actual sound test on one selected AHU in accordance with AMCA
Standard 300-96. Reverberant Room Method for sound testing of fans, and AMCA Standard 210,
Laboratory Methods of Testing Fans for rating. The mechanical engineer shall select the test AHU after
review of the submittal.
Air handling unit sound power data shall be submitted for review by Owner’s representative. Sound power
data shall be given at the supply connection (s) (outlet) and return connection (s) (inlet) in addition to
radiated sound power from the cabinet.
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Raw fan sound power data shall be derived from tests done in accordance with AMCA Standard 300-96.
Data extrapolated from non-like fan sizes and types scheduled are not acceptable. Attenuation assumed
for the cabinet configuration, type of insulation, opening locations and sizes, etc., shall be verified
through actual test measurements. The mechanical engineer may, at his option, request copies of such
tests.
If the AHU manufacturer is incapable of performing the AMCA Standard 300 sound test, substitute
method shall be proposed for review by the mechanical engineer. The proposed substitute method shall
clearly identify the measurement instrumentation, the test reference to a nationally known test standard
and qualifications of personnel who will perform the test.
The mechanical and acoustics engineers shall be allowed to witness the sound test. The AHU
manufacturer shall notify the mechanical engineer a minimum of ten (10) days prior to test as to the
location and date of the sound test. The travel costs incurred by test witnesses shall be borne by the
equipment manufacturer.
If the sound test indicates the AHU noise levels exceed levels of units specified, the Contractor shall take
corrective measures to reduce the sound. Any modifications that are necessary to meet scheduled
sound levels shall be applied to all AHU’ s represented by the test unit. Test results shall be submitted to
the Owner’s Representative for approval prior to shipment of any equipment.
O. Air Performance Testing
The manufacturer shall perform an air performance test on one selected unit in accordance to AMCA
210-85/ANSI 51-1985 “Standard for Laboratory Measurement of Airflow”. Air handling unit air performance data shall be submitted for review by Owner’s representative. The mechanical engineer shall be
allowed to witness the airflow test. The AHU manufacturer shall notify the mechanical engineer a minimum of ten (10) days prior to test as to the location and date of the test. The travel costs incurred by test
witnesses shall be borne by the equipment manufacturer.
P. Air Leakage Test
Air handling unit leakage data shall be submitted for review by Owner’s representative. The mechanical
engineer shall be allowed to witness the leakage test. The AHU manufacturer shall notify the mechanical
engineer a minimum of ten (10) days prior to test as to the location and date of the test. The travel costs
incurred by test witnesses shall be borne by the equipment manufacturer.
The manufacturer shall perform the leak test as follows:
A U-Tube manometer shall be used to measure the static pressure exerted on the unit cabinet. The
manometer must have graduations no larger than 0.2” (inches of water gauge).
A pressure blower that is capable of producing the required pressure without operating at a stall shall be
used to perform the test. The pressurizing fan shall be attached to a flow metering station which shall
measure the volume flow rate by pressure drop through calibrated nozzles. The test apparatus shall
have a means of dampering such that the required pressure may be exerted without over-pressurizing
the cabinet.
Procedure
The air-handling unit shall have all duct openings, damper, and louver openings sealed with plywood or
sheet metal and caulked or taped.
The static pressure tap shall be arranged with one leg open to atmosphere and one leg tapped to the
cabinet interior.
A static pressure load of 1.5 times the maximum calculated internal static pressure or 10”
whichever is less, will be exerted on the cabinet.
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The leakage rate will be recorded at the flow measuring apparatus. The air density at which the test was
performed will be determined. The test results will be corrected to standard air. An AHU will be considered
acceptable if it leaks at a rate of not more than one percent of the design volume.
Q. Warranty and Start-Up Service
Manufacturer shall provide factory start-up service for each air-handling unit. Manufacturer shall provide a
one (1) year parts and labor warranty.
PART III - EXECUTION
DELIVERY, STORAGE, AND HANDLING
Store in clean dry place and protect from weather and construction traffic. Handle carefully to avoid damage to components, enclosures and finish. All fans must be periodically rotated during storage period per manufacturer recommendation.
ENVIRONMENTAL REQUIREMENTS
Do not operate units for any purpose, temporary or permanent, until ductwork is clean, filters are in place, bearings are
lubricated, and fan has been test run under observation
INSTALLATION
A.
Install in accordance with manufacturer’s instructions.
B.
Install in conformance with ARI 435.
C.
Assemble high-pressure units by bolting sections together. Isolate fan section with flexible duct connections.
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