Bohn H-IM-AH Installation Manual

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
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 sucient 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 sucient 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 eciency 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
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 conguration�
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 eectiveness of vibration isolators�
The water supply should always be connected to the bottom inlet of the coil� The coil connections are identied 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
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