5
AIR FLOW
AIR FL
OW
Figure 10
LESS THAN
7 INCHES
FIGURE 9
OFFSET
AT LEAST
9 INCHES
AIR FLOW
Figure 7
AIR FLOW
Figure 6
AIR FLOW
Figure 5
HIGHBOY FURNACE
(Figure 8)
Installation beneath furnace.
Filter mounts horizontally,
where return air enters from
below. Raise furnace and in-
stall beneath base.
COUNTERFLOW
FURNACE (Figure 6)
Filter is mounted horizontally
in return duct or plenum, just
above furnace.
HIGHBOY FURNACE
(Figure 7)
Side installation. Filter is
mounted vertically, where
return air enters side inlet
of furnace.
OFFSET INSTALLATION
(Figure 9)
Typical use of duct offset to match air filter opening.
If duct connection to furnace allows less than nine
inches for mounting the air filter, shorten the lateral
trunk, or attach an offset fitting to the elbow.
HORIZONTAL FURNACE
(Figure 10)
Filter is mounted vertically in
the return duct near furnace.
BASEMENT FURNACE
(LOWBOY) (Figure 5)
Filter is mounted horizon-
tally in return plenum, just
above furnace.
TYPICAL MOUNTING POSITIONS
