Sterling QVES - Manual (Page 7)

7
Figure 3 - Recommended Design for Field
Installation of Ductwork for Straight-
Through Arrangement
Figure 4 - Recommended Ductwork Design for
Elbowed Arrangement
DUCTWORK
Properly designed and installed ductwork, providing
a uniformly distributed flow of air across the 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 250°F (121°C) minimum.
Any attempt to straighten the 90°
duct connection fl anges 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
baffl es and/or turning vanes in the ductwork.
Figures 3 and 4 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 specifi ed on the appliance
rating plate.
INSTALLATION
COMBUSTION INLET AIR VENTILATION
Inlet Air From Another Room — If the duct furnace is
installed in a tightly constructed 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/hr.
(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 must not be smaller than one square
inch (6.452 square centimeters) of free area for each
2500-3000 Btu/hr. (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.
Insure that all hardware used in
the suspension or each unit heater is more than
adequate for the job. Failure to do so may result
in extensive property damage, personal injury
or death.