Dip Switch
See “Wiring
Diagram”
for switch settings
24 VAC 
HUM
FUSE
DEHUM
Diagnostic Light
115 VAC HUM
EAC
A07780
!WARNING
CARBON MONOXIDE POISONING HAZARD
Failure to follow this warning could result in personal injury or death.
Cool air passing over heat exchanger can cause condensate to form resulting in heat exchanger failure.
Connections
NOTE: Return air can enter through either side, both sides, the bottom or a side and the bottom. Return air can not enter through rear of the furnace. When the furnace is located in an area near or adjacent to the living area, the system should be carefully designed with returns to minimize noise transmission through the return grille. Any blower moving a high volume of air will produce audible noise which could be objectionable to when the unit is located very close to living areas. It is advisable to route the return
58HDV
Fig. 41 - Control Connections
DUCTWORK AND FILTER
!WARNING
CARBON MONOXIDE POISONING HAZARD
Failure to follow this warning could result in personal injury or death.
Do NOT draw return air from inside a closet or utility room where furnace is located. Return air duct MUST be sealed to furnace casing.
Installation
NOTE: Design and install the air distribution system to comply with Air Conditioning Contractors of America manuals and/or NFPA pamphlets 90A and 90B or other approved methods that conform to local codes and good trade practices.
1.When furnace supply ducts carry air outside furnace area, seal return air duct to furnace casing and terminate duct outside furnace space.
2.Install air conditioning cooling coil (evaporator) on outlet side of furnace.
3.For furnaces installed without a cooling coil, it is recommended that the outlet duct be provided with a removable access panel. This panel should be accessible when the furnace is installed so the exterior of the heat exchanger can be viewed for inspections. The access panel MUST be sealed to prevent leaks.
4.If separate evaporator and blower units are used, install good sealing dampers for air flow control. Chilled air going through the furnace could cause condensation and shorten the furnace life.
NOTE: Dampers (field supplied) can be either automatic or manual. Manually operated dampers MUST be equipped with a means to prevent furnace or air conditioning operation unless damper is in the full heat or cool position.
air ducts under the floor or through the attic.
1.For side connections using a 16″ x 25″ (406.4 x 635mm) filter, cut out the embossed area shown in Fig. 42. This will
provide a 141/2″ x 221/2″ (368.3 x 571.5mm) approximate opening.
A = 14 /2″ (368.3mm) Height of Cutout for 16″ x 25″ (406.4 x 635mm) Filter B = 221/2″ (571.5mm) Width of Cutout for 16″ x 25″ (406.4 x 635mm) Filter
B
Embossed Area on Side of Furnace
A
Furnace
Bottom
A07728
Fig. 42 - Side Return Air Cutout
NOTE: Furnaces with 5 TONS cooling capacity may require two(2) side returns or one side return with bottom return.
2.Bottom returns can be made by removing the knockout panel in the furnace base. Do NOT remove
3.Installation of
4.
5.If air return grille is located close to the fan inlet, install at least one, 90° air turn between fan and inlet grille to reduce noise.
NOTE: To further reduce noise, install acoustical air turning vanes and/or line the inside of duct with acoustical material.
Sizing
Existing or new ductwork MUST be sized to handle the correct amount of airflow for either heating only or heating and air conditioning.
Insulation
1.Insulate ductwork installed in attics or other areas exposed to outside temperatures with a minimum of 2″ (50.8mm) insulation and vapor barrier.
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