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Bulletin No� H-IM-AH August 2002 Part Number 4346B001
(Replaces H-IM-71A, August 2002)
Installation &
Operations Manual
Air Handler Unit
Table of Contents
Inspection �������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������2
Shipment of Units
Handling
Suspended Units
Installation
Motors & Drives
Steam Coils
Steam Coils �����������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������3
Water Coils
Direct Expansion Coils
Start-up ������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������4
Maintenance
Condensate Drain Traps
Internal Isolation
Section Assembly �����������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������5
Coil Stacking
Freezing Temperatures �������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������6
Weights ������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������7
Shipment of Sections
Filter Quantities ���������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������������8
Replacement Parts
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Installation and Operations Manual
Inspection
Shipment should be checked against the bill of lading
to verify that all items listed have been received� All
parts should be carefully inspected to determine if any
damage was incurred in shipment�
Any shortage and/or claims for damage should be
immediately reported to the delivering carrier, followed
by ling a claim for shortages and/or damages�
Shipment of Units
Depending on the unit size and accessories included, the
shipment may be in two or more sections�
Handling
Special care should be taken when handling and
assembling component sections of the unit� Rough
handling at the jobsite can result in damaged bearings,
bent shafts, etc�
All units are shipped on wooden skids� It is recommended
that units not be moved removed from skids until they
are at a place of installation� The mounting legs/rails
provided for isolators should be used when lifting units
into place�
Suspended Units
Sizes 03 through 41 may be ceiling-suspended from
the mounting legs/based rails with 5/8” diameter rods
(not furnished)� These rods will pass through the 11/16”
diameter mounting holes provided� Sizes 50, 65 and 75
cannot be ceiling-suspended�
Installation
It is very important that the unit be installed in a level
position to prevent distortion and to ensure proper
damper operation and coil drainage�
Allow sucient space around the unit for proper
maintenance� Consider factors such as lter removal for
cleaning or replacement, access to all removal panels,
removal of coils and shaft if necessary, lubrication access
or motor belt adjustment� Canvas duct connections
should be used between the unit and supply and return
air ducts�
Units are furnished with 1-1/4” FPT drain connection
on each side of the coil section� The drain line from
the drain pan connection must be adequately pitched
and should have a water seal of sucient depth to
compensate for the air pressure within the units�
(See Condensate Drain Traps on page 4�)
When the unit is located on the roof, it must be mounted
on support beams that span load-bearing walls� If not,
excessive vibration may occur because of the resiliency
of the roof�
2 Part # 4346B001
© 2007, Heatcraft Refrigeration Products LLC
Fan noise is a function of fan design, volume ow,
pressure and fan eciency and could be loud enough
to disturb those in occupied areas� Therefore, on critical
applications we recommend extra sound attention�
Motors and Drives
All units will normally be shipped with motor and drive
installed� When mounting a motor on the adjustable
base (installed on the unit), extreme care should be
taken to ensure proper alignment and belt tension� All
electrical work should be done in strict accordance with
local codes and regulations�
Steam Coils
Type J and NFS coils have supply and return connections
on the same end� Types R, S and RA coils have
supply and return connections on opposite ends�
Type NFD coils have supply connections on each end
of the coil, with a single return connection on one
end only�
All piping should be in accordance with accepted
industry standards and local codes� Support all piping
independent of coil and provide adequate swing joints in
all piping to absorb expansion and contraction strains�
Run return piping the full size of the coil return
connection from the coil to a dirt pocket� (Do not use
reducing ttings�) Install drip traps in steam mains ahead
of coils� Do not drip steam mains through the coils�
Install a vacuum breaker (1/2” 15º check valve) ahead
of the trap on low-pressure, open-gravity return systems
and on high pressure systems� Install a 1/2” 15º swing
check valve in a 1/2” vacuum-equalizing line, bypassing
the condensate trap, on low pressure vacuum systems�
When two or more steam coils are furnished in a unit,
provide separate traps for each coil� Size traps with ample
capacity using the maximum heating load and service
factor recommended by the trap manufacturer�
Select control valves in accordance with the
recommendations of the control manufacturer using
actual heating loads�
Install suitable strainer ahead of all automatic valves and
traps to catch dirt and scale� Provide adequate air vents
to expel air and other non-condensable material�
Control valves used for type J, NFS, RA and NFD coils
must be gradual-acting, modulating type with veeport�
Where a control valve is used for type S or R coils and
the entering air temperature is below 35ºF, use a twoposition valve� Locate control element in the entering air
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Air Handler Units
stream so that valve will remain open with a minimum
of ve pounds steam pressure when the entering air
temperature is below 35ºF� At system start-up, the
damper should remain closed for approximately ten
minutes after the steam valve is opened�
Properly locate all temperature sensing elements at a
point of true average air mixture temperature� Refer to
Diagrams 1 and 2 for controls positioning and piping
conguration�
When face and bypass dampers are used, it is good
practice to install a valve that closes with the face damper
to prevent overheating because of damper leakage or
heat from the exposed coil face�
Diagram 1� Typical Steam Coil Piping
Low Pressure, Open Gravity Return System
Steam Main
Water Piping
All piping must be supported independent of coils�
Swing joints or exible ttings must be provided to
absorb expansion and contraction strains� Rigid piping
may also reduce eectiveness of vibration isolators�
The water supply should always be connected to the
bottom inlet of the coil� The coil connections are
identied with stickers�
Water coils (3 through 10 rows) are supplied with a vent
and drain connection (1/4” MPT) that extends through
the unit casing� Coils must be adequately vented in order
to prevent air binding� For protection of coils exposed to
freezing temperatures, refer to page 6�
Direct Expansion
Both the liquid distributor and the suction line extend
through the casting� The expansion valve utilized must
be the external equalizer tube type� The expansion valve
bulb must be placed on the suction line between the
coil and the 1/4” external equalizer tube� Never put the
bulb in a trap�
Gate Valve
Strainer
Control Valve
Union
Vacuum Breaker
1/2”-15” Check Valve
Vent
Gate Valve
12” Minimum
Union
Strainer
Dirt Pocket
Union
Combination Float
and
Thermostatic Trap
Return Main
Diagram 2� Typical Steam Coil Piping
High Pressure System
Gate Valve
Strainer
Control Valve
Union
Vacuum Breaker
Vent
1/2”-15” Check Valve
Open Vent
Steam Main
All refrigerant piping practices should be in accordance
with local codes and latest ANSI Standard B9 Safety Code�
Hard-drawn type L or K copper tubing should be used�
Soft tubing may be used where bending is required,
provided it is in accordance with local codes�
Remember to check for adequate vacuum, clear tubes of
foreign material, etc�
Gate Valve
12” Minimum
Union
Strainer
Dirt Pocket
Union
Float or
Bucket Trap
Return Main
Air Handler Unit Installation & Operations Manual, August 2002 3