Filters - Read This Section Before Installing The Return Air Ductwork; Upright Installations; Circulation Air Filters - Intertek MES80 Installation Instructions Manual

When a furnace is installed so that supply ducts carry air
circulated by the furnace to areas outside the space containing
the furnace, the return air shall also be handled by a duct
sealed to the furnace casing and terminating outside the space
containing the furnace.
E
DGES OF SHEET METAL HOLES MAY BE SHARP
PRECAUTION WHEN REMOVING SHEET METAL FROM RETURN AIR
.
OPENINGS
Filters - Read This Section Before Installing The
Return Air Ductwork
Filters must be used with this furnace. Discuss filter
maintenance with the building owner. Filters do not ship with
this furnace, but must be provided by the installer. Filters must
comply with UL900 or CAN/ULCS111 standards. Damage or
repairs due to failure to install filters in the furnace are not
covered under the warranty.
NOTE: An undersized opening will cause reduced airflow.
Refer to the Filter Sizing Chart to determine filter area
requirements.

Upright Installations

Depending on the installation and/or customer preference,
differing filter arrangements can be applied. Filters can be
installed in the central return register or a side panel external
filter rack kit (upflows). As an alternative, a media air filter or
electronic air cleaner can be used as the primary filter. The
following figure shows possible filter locations.
CENTRAL
RETURN
GRILLE
SIDE RETURN
EXTERNAL FILTER
RACK KIT
(EITHER SIDE)
Upright Upflow
WARNING
. U
SE GLOVES AS A
AIR FLOW
Figure 12

Circulation Air Filters

One of the most common causes of a problem in a forced
air heating system is a blocked or dirty filter. Circulating air
filters must be inspected monthly for dirt accumulation and
replaced if necessary. Failure to maintain clean filters can
cause premature heat exchanger failure.
A new home may require more frequent replacement until all
construction dust and dirt is removed. Circulating air filters are
to be installed in the return air duct external to the furnace
cabinet.
Upflow / Horizontal
Models
*MES800403AU 1 - 16 X 25 Side or 1 -14 X 24 Bottom Return
*MES800603AU 1 - 16 X 25 Side or 1 -14 X 24 Bottom Return
*MES800604BU
*MES800804BU
*MES800805CU 2 - 16 X 25 Side Return, 1 - 20 X 25 Bottom Return
^Larger filters may be used, filters may also be centrally located
19
Minimum Recommended Filter Size^
1 - 16 X 25 Side or Bottom Return
1 - 16 X 25 Side or Bottom Return
Table 7