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18-CE12D1-1D-EN
1.
Upflow Furnaces:
When the upflow furnace is installed in the horizontal right or left
application and a return duct is attached to the top side, do not
install a filter in the return duct directly above the furnace. Install
the filter in a remote location.
When the upflow furnace is installed in the horizontal right or left
application and a close coupled (less than 36") return duct is
attached to the bottom side of the furnace as shown above,
securely attach a 1/2" mesh metal hardware cloth protective
screen to the inside bottom of the filter grill
to prevent personal
injury from contacting moving parts when reaching into
the return opening to replace the filter.
Close coupled (less than 36") return (filter directly beneath
bottom side return) is not recommended due to noise
considerations.
2.
Connect the duct work to the furnace. See Outline Drawing for
supply and return duct size and location.
Flexible duct connectors are recommended to connect both
supply and return air ducts to the furnace.
If only the front of the furnace is accessible, it is recommended
that both supply and return air plenums are removable.
3.
When replacing a furnace, old duct work should be cleaned out.
Thin cloths should be placed over the registers and the furnace
fan should be run for 10 minutes. Don’t forget to remove the
cloths before you start the furnace.
4.
The horizontal installation of the upflow furnace requires
an external filter section. Filter kits are available for
horizontal applications.
Figure 1. Horizontal furnace with side return
FILTER
CLOSE COUPLED (LESS THAN 36”)
RETURN (FILTER DIRECTLY BENEATH BOTTOM
SIDE RETURN) NOT RECOMMENDED DUE TO
NOISE CONSIDERATIONS. IF USED, SECURELY
ATTACH 1/2” MESH METAL HARDWARE CLOTH
PROTECTIVE SCREEN TO THE INSIDE BOTTOM
OF THE FILTER GRILL.
LESS THAN 36”
RETURN AIR FILTERS FOR UPFLOW FURNACE IN HORIZONTAL
CONFIGURATION
When the Upflow Furnace is installed in the horizontal configuration,
the return air filters must be installed exterior to the furnace cabinet.
Remote filter grilles may be used for homeowner convenience or the
filters may be installed in the duct work upstream of the furnace.
TYPICAL DOWNFLOW FURNACE RETURN AIR FILTER
INSTALLATIONS
Filters are not factory supplied for downflow furnaces. Filter size
needed will be dependent on type of filter and CFM requirement.
Filters must be installed externally to the unit.
Downflow Return Air Filters
Furnace Width
Filter
Qty and Size
17–1/2”
2 — 14” x 20” x 1”
21”
2 — 16” x 20” x 1”
24–1/2”
2 — 16” x 20” x 1”
