15
Over-the-Floor Return Air System
(Non-Ducted)
1.
If floor underneath furnace is made of com-
bustible material, locate a pan fabricated of
non-combustible material with 1" upturned
flanges under furnace return air opening
(see Figure 16). Ensure that return air
passage has no openings through support-
ing structure that would permit flame or hot
gases to travel from space below up into
space above supporting structure.
2.
Use optional upflow stand with filters or
construct a suitably braced mounting plat-
form in closet (see Figure 15 or 16).
3.
Install 240V supply circuit(s) and 24V wir-
ing to closet (see Figure 14 for appropriate
locations).
4.
Position optional coil cabinet onto upflow
stand or mounting platform and secure with
three or more fasteners.
5.
Position furnace in upflow mode onto coil
cabinet and secure with two or more fasteners.
6.
Use optional upflow duct connector or field
supplied connector to attach furnace to
overhead supply duct. (see Figure 15)
7.
Install return air grille in closet preferably at
same level as upflow stand or below mount-
ing platform (see Figure 16).
NOTE: Be certain to provide an adequate free
return air area as described under Return Air
Codes and Requirements and Closed-Off Space
Requirements.
Through-the-Floor Return Air System (Ducted)
1.
Prepare Floor Opening(s):
a. Mark floor opening(s) as shown in Figure
17. Provide minimum clearances at rear
and left side walls of closet for installation of
furnace and wiring.
b. Cut floor opening on outside edge of
marked line so that opening is slightly larger
than area marked.
c. Additional provisions may be necessary
for optional air conditioning if refrigerant
lines are installed other than at the front of
the furnace.
2.
If return air duct is made of combustible
material, locate a pan fabricated of non-
combustible material with 1" upturned
flanges under furnace return air opening.
Ensure that return air passage has no
openings through supporting structure that
would permit flame or hot gases to travel
from space below up into space above
supporting structure.
Coil Cabinet
Air Filter
Braced
Mounting
Platform
Front
Grille
Non-combustible
Pan or
Enclosure
WALL
FLOOR
Figure 16. Over-the-Floor Return Air
System
Figure 15. Over-the-Floor Return Air
System with Upflow Stand
Upflow Duct
Connector
Furnace
Filters
Upflow Stand
3.
Install 240V supply circuit(s) and 24V wir-
ing to closet (see Figure 14 for appropriate
locations).
4.
Position optional coil cabinet over floor
cutout and secure with three or more fas-
teners.
5.
Position furnace onto coil cabinet and se-
cure with two or more fasteners.
6.
Use optional upflow duct connector or field
supplied connector to attach furnace to
overhead supply duct (see Figure 15).