507768-04P
Page 11 of 56
Issue 1933
Return Air Guidelines
Return air can be brought in through the bottom or either
side of the furnace installed in an upflow application. If the
furnace is installed on a platform with bottom return, make
an airtight seal between the bottom of the furnace and the
platform to ensure that the furnace operates properly and
safely. The furnace is equipped with a removable bottom
panel to facilitate installation.
Markings are provided on both sides of the furnace cabinet
for installations that require side return air. Cut the furnace
cabinet at the maximum dimensions shown on Page 2.
Furnace applications which include side return air and a
condensate trap installed on the same side of the cabinet
(trap can be installed remotely within 5 ft.) require either a
return air base or field-fabricated transition to accommodate
an optional IAQ accessory taller than 14.5”. See Figure 14.
Figure 14. Side Return Air
(with Transition and Filter)
Return
Air
Plenum
Transition
20” X 25” X 1”
(508mm X 635mm X 25mm)
Air Filter
Figure 15. Optional Return Air Base
(Upflow Applications Only)
