Quick Start Manual
8
Installation, Operation & Maintenance  WDG AIR HANDLER SERIES  Heat Controller, LLC
Installation
Air Handlers are designed for upfl ow, horizontal, and downfl ow 
applications. The coils have a dry nitrogen holding charge and 
are equipped with brazing stub refrigerant connections for easy 
installation. Both models come equipped with a factory installed 
TXV.
The installer should read the installation manual supplied with 
the compressor section for refrigerant line set sizing, connec-
tion procedure, and other important information pertaining to the 
system installation.
The installer should:
1. Where precise forming of refrigerant lines is required, a copper 
tubing bender is recommended for small diameter tubing. One 
should avoid sharp bends and contact of the refrigerant lines 
with metal surfaces.
2. Refrigerant lines should be protected where they pass through 
the raw edges of holes.
3. Air Handler must be level for proper condensate drainage.
4. Seal the openings into the cabinet to reduce risk of conden-
sate blow off from the coil.
Air Handler Installation
 WARNING! 
WARNING! Electric furnaces may be connected to more than 
one supply circuit.
Charging the System
Air Handlers are designed to match HTS split units. For correct 
charging, please refer to the Compressor Section IOM.
Upfl ow Installation
1. Position unit on plenum box or other suitable foundation. Provide 
a minimum height for proper unrestricted airfl ow based on CFM 
requirement for each unit size.
2. If a return air duct is connected to the air handler, it must be the 
same dimensions as shown in the outline drawing in Figure 2.
3. Plenum box and unit should be isolated from the foundation 
using a suitable isolating material.
4. Openings where fi eld wiring enters the cabinet must be 
completely sealed. Location of power entry is shown on the 
outline drawing. 
5. After ductwork connections are made, seal airtight and per local 
codes.
Downfl ow Installation
1. Position unit on plenum box or other suitable foundation. Provide 
a minimum height for proper unrestricted airfl ow based on CFM 
requirement for each unit size.
2. If a return air duct is connected to the air handler, it must be the 
same dimensions as shown in the outline drawing in Figure 2.
3. Plenum box and unit should be isolated from the foundation 
using a suitable isolating material.
4. Openings where fi eld wiring enters the cabinet must be 
completely sealed. Location of power entry is shown on the 
outline drawing.
5. After ductwork connections are made, seal airtight and per local 
codes.
6. The unit is then placed with the blower side down and the coil is 
replaced on the coil channel supports with the drain connections 
at the bottom. The unit is now in downfl ow position with front 
access.
  Position the ECM wire harness connection at the 4 to 8 o’clock 
position to prevent condensation from entering motor controller.
7. If a return duct is connected to the air handler, it must be the 
same dimensions as the return opening.
8. After ductwork connections are made, seal airtight and per local 
codes.
Horizontal Right Installation
  For maximum effi ciency and customer ease of fi lter 
maintenance, it is recommended that a properly sized remote 
fi lter grille be installed for horizontal applications. Airfl ow should 
not exceed the face velocity of the fi lter being used. The factory 
installed fi lter should then be removed from the unit.
1. To convert the unit to horizontal right, front access, slide the coil 
out on the coil channel supports and rotate the complete coil 180 
degrees.
2. The coil is then inserted back into the cabinet on the opposite 
side coil channel supports. The unit is now horizontal right with 
front access.
  Position the ECM wire harness connection at the 4 to 8 o’clock 
position to prevent condensation from entering motor controller.
3. If the unit is suspended, it must be supported from the bottom 
near both ends as well as the middle to prevent sagging. The 
service access must remain unobstructed. If the unit is supported 
along the length of the front and back with rails, the air handler 
only needs to be suspended at both ends. See Figure 1.
  If the unit is not suspended it must be supported as mentioned 
above and isolated carefully to prevent sound transmission. 
Vibration isolators (purchased locally) must be placed under the 
unit.
4. It is always recommended that an auxiliary drain pan be installed 
under a horizontal air handler (See Condensate Piping) to prevent 
possible damage to ceilings.
5. Isolate the auxiliary drain pan from the unit or from the structure.
6. Connect the auxiliary drain line to a separate drain line (no trap is 
needed in this line) and terminate according to national and local 
codes.
7. If a return duct is connected to the air handler, it must be the 
same dimensions as the return opening shown in the outline 
drawing on Figure 2.
8. Openings where fi eld wiring enters the cabinet must be 
completely sealed.
9. After ductwork connections are made, seal airtight and per local 
codes.
Horizontal Left Installation
1. For maximum effi ciency and customer ease of fi lter 
maintenance, it is recommended that a properly sized remote 
fi lter grille be installed for horizontal applications. Airfl ow should 
not exceed the face velocity of the fi lter being used. The factory 
installed fi lter should then be removed from the unit.
2.  Unit is shipped from the factory in the upfl ow or horizontal 
left confi guration. Unit conversion is not required. Conversion 
is required: Rotate motor to ensure connection at the 4 to 8 
o’clock position.










