Installation
GUNE-SVX001A-EN
11
Ductwork
Properly designed and installed ductwork, providing a
uniformly distributed flow of air across all surfaces of the
heat exchanger, is essential to satisfactory unit
performance and life of the equipment.
All duct connection flanges/seams must be sealed to
prevent air leaks. Sealant/tape must be suitable for
temperatures of 250°F (121°C) minimum.
Note:
Any attempts to straighten the 90° duct connection
flanges on the duct furnaces will affect the
operation of the furnace and will void the warranty.
If uniform air distribution is not obtained, install additional
baffles and/or turning vanes in the ductwork.
illustrate recommended ductwork
designs for both the straight-through and elbowed air inlet
arrangements.
Access panels large enough to observe smoke and
reflected light, and to detect the presence of leaks in the
heating equipment, are required both upstream and
downstream from gas duct furnaces. These panels must
be sealed to prevent air leaks. If allowed by local
regulations, install canvas connectors between the
ductwork and fan discharge opening to eliminate the
transmission of mechanical vibration.
Air Flow
The installation is to be adjusted to obtain an air
throughput within the range specified on the appliance
rating plate.
Combustion Inlet Air Ventilation
Inlet Air From Another Room
If the duct furnace is installed in a separate room or
compartment, provide two inlet air openings. The size of
each vent opening should be no less than one square inch
(6.452 square centimeters) of free area for each
1000 Btu/h (293 W) input. Each opening must not be less
than 100 square inches (645 square centimeters).
Inlet Air From Outdoors
If the enclosed space is to have inlet combustion air from
the outside, the vent opening should be no less than one
square inch (6.452 square centimeters) of free area for
each 2500–3000 Btu/h (733–879 W) input. Each opening
must not be less than 100 square inches (645 square
centimeters).
Bypass
When a gas duct furnace is installed to operate in
conjunction with a summer air conditioning system, the
CFM air delivery of the system blower should be adjusted
to meet the design air volume requirements for cooling. If
this CFM delivery is greater than that required for heating,
resulting in a low air temperature rise, install a damper
bypass around the gas duct furnace to bypass a portion of
the air.
Figure 5.
Recommended ductwork design for straight-
through arrangement
Figure 6.
Recommended ductwork design for elbowed
arrangement