MG2S Installation Manual

12
For proper air circulation, closet installations require
a return air grill installed in the door or side wall that
exchanges with the living area of the home. A partially
louvered door may also be used across the opening. Grilles
placed in a side wall require a 6” clearance from the wall
to the furnace so that the air may enter the front grille
of the furnace. All return air systems, including the floor
and ceiling systems, must meet the following conditions:
• The return air opening, regardless of its location in the
closet, must not be smaller than size specified on unit
data label. If located in the floor, the opening must be
provided with a means of preventing its inadvertent
closure by flat object(s) placed over the opening.
• The cross-sectional area of the return duct system (in
floor or ceiling) leading into the closet must not be less
than 235 in
2
(1,516 cm
2
).
CAUTION:
HAZARD OF ASPHYXIATION: Negative pressure
inside the closet, with closet door closed and
the furnace blower operating on high speed,
shall be no more negative than minus 0.05 inch
water column.
• Test the negative pressure in the closet with the air-
circulating fan operating at high speed and the closet
closed. The negative pressure in the closet must not
be less than minus 0.05 inches water column with the
closet door closed and the fan operating at high speed.
The negative pressure is to be no more negative than
minus 0.05” water column as this indicates a dirty filter
or a restricted return air system.
• For closet installation with less than 6” front clearance,
but not less than 1”, a louvered door must be used
having a minimum 250 in
2
(1,613 cm
2
) free area opening
directly in line with openings in the furnace door. For
1” clearance from furnace, use a fully louvered door
with at least 400 in
2
(2,580 cm
2
) of free airflow area.
Furnace Filter
WARNING:
Never operate the furnace without a filter in place.
Accumulating dust in the return air can build
up on internal components, resulting in loss of
efficiency, equipment damage, and possible fire.
• Front return furnaces are supplied with a single reusable
air filter when shipped from the factory. Accessing the
filter does not require tools and can be easily removed
from the inside of the access door. The filter is secured
to the door with a retaining bracket.
• Top return furnaces are shipped with a non-reusable
single 18”x18”x1” air filter from the factory. Accessing
the filter does not require tools and can be easily
removed from inside the blower compartment. The
filter is secured with a U-shaped retaining bracket. It
is recommended that the filter be cleaned or replaced
monthly. Newly built or recently renovated homes may
require more frequent changing until the construction
dust has minimized.
1. Slide the standard 18”x18”x1” filter into the space
between the combustion air pipe and the blower
assembly. See Figure 7 (page 13). NOTE: Make
sure the airflow arrows on the filter point towards
the blower assembly.
2. Push the filter to the rear of the furnace cabinet and
angle it up over the blower. Make sure the filter is
pushed back as far as possible.
3. Position the filter retainer under the filter and insert
the stepped ends into the 0.25 holes in the rear of
the furnace. NOTE: The stepped ends should be
facing upwards in the holes.
4. Evenly align the filter over the opening in the top of
the furnace cabinet and position the other end of
filter retainer up over the flange in the furnace’s top
panel. NOTE: To properly secure the filter, make
sure the filter retainer is properly positioned in the
top panel of the furnace. There should be no visible
air gaps. The retainer may slide left or right slightly,
but must not have any movement between the front
and rear. See Figure 7.
• Replacement filters are available at most local retailers.
Inspect filters frequently and replace when necessary
with filter of same dimensional size. Filters designed to
remove smaller particles such as pollen, may require
additional maintenance.
Dampers
An automated shut off damper is required when the home
is air conditioned by a self-contained unit. A damper
is required to prevent chilled air from flowing over the
furnace heat exchanger. This damper is designed to fit
in the feeder duct cavity, directly under the furnace. For
proper installation, refer to the instructions provided with
the damper. See replacement parts list provided online.