MG3P Installation Manual

15
NOTES:
With reducer installed: Opening to duct is 10-1/4” x 13-1/4”.
With reducer removed: Opening to duct is 13-1/4” x 13-1/4”.
REDUCER
(See Notes)
FELT-SEAL
SPACER
S
DUCT CONNECTOR TABS
FIBERGLASS
INSULATION
Figure 12. Duct Connector
REAR WALL OF CLOSET OR ALCOVE
10”
13 1/4”
13 1/4”
Floor Cut-Out for
Duct Connector
FURNACE CABINET OUTLINE
FUEL
LINE
HOLE
AL
T. FUEL
LINE HOLE
C
L
C
L
Figure 13. Floor Cutout Dimensions
If Floor Cavity
(“X”) is:
Duct Connector
Type & Part Number
Finger Tab Screw Down
7/8” (22) 901987A 904008
2” (51) 901988A 904009
4-1/4” (108) 901989A 904010
6-1/4” (159) 901990A 904011
8-1/4” (210) 901991A 904012
10-1/4” (260) 901992A 904013
12-1/4” (311) 901993A 904014
NOTE: Dimensions shown as Inches (Millimeter)
Table 3. Duct Connector Sizes
“X”
FLOOR OPENING
FLOOR CAVITY
SUPPLY AIR DUCT
Downflow Furnace Installation
NOTE: These Installation procedures are suggested for typical
furnace installations. Since all installations are different from
each other, the sequence of instructions may differ from the
actual installation.
WARNING:
The furnace must not be installed directly on
carpeting, tile, or any combustible material other
than wood flooring.
The MG3S series gas furnace is certified for use on wood flooring
or supports, but must be installed on a special duct connector
(Figure 12). This factory supplied accessory must be installed
in the floor cavity and attached to the supply air duct before the
downflow furnace is installed.
The depth of the floor cavity (shown as “X” in Table 3) will
determine the duct connector size to use. Several connector
sizes are listed in Table 3.
Locating & Cutting Floor Openings
IMPORTANT NOTE:
Cut-outs in the floor, must be carefully located to avoid
misalignment of the furnace. To locate standard ducts, see
Figure 8 (page 10).
1. Measure from the rear wall or alcove and mark the centerline
of the cut-out on the floor. Using the centerline as a starting
point, draw the rest of the duct cut-out to the dimensions
shown in Figure 13.
2. Cut out the floor opening to within 1” of the actual cutout
drawn.
3. Measure from the top of the floor down to the top of the supply
air duct to obtain the depth of the floor cavity.NOTE: The depth
of the floor cavity shown as “X” in Table 3 will determine the
correct duct connector.
4. Determine which duct connector to use from the table.
5. Measure and drill gas hole and cut out for cooling coil (if
applicable).
Installing Finger Tabbed Duct Connectors
The standard duct connector is designed for use on ducts
12” in width. However ducts narrower than 12” may not allow
sufficient clearances for this type of installation. See Narrow
Duct Attachment for an alternate installation method.
1. Center the duct connector in the floor opening with bottom
tabs resting on top of the supply air duct.
2. Mark the cut-out area on the supply air duct by tracing
around the connector tabs (Figure 14 (page 16)) of the
duct connector.
3. Remove the duct connector and cut out the marked area of
the supply air duct 1/16” larger the actual cutout drawn.
4. Install the duct connector back in the floor opening with the
bottom tabs extending into the supply air duct.
5. Install the mounting plate (Figure 14) under the back side of
the duct connector. Align the screw holes in both components.
6. Secure the duct connector and the mounting plate to the
wood floor with appropriate size screws.
7. Secure the duct connector and the mounting plate to the
wood floor with appropriate size screws.
8. Install 2 plates (Figure 15) on top of the duct connector, one
on each side (left and right) of the opening. Align the screw
holes in both components.
9. Secure both plates and duct connector to the wood floor with
appropriate size screws.