Filters; Duct System - Lennox G61MPVT-36B-070 Installation Instructions Manual

G61MPVT UNIT
PROPERLY
SIZED FLOOR
OPENING
FIGURE 10
Installation on Cooling Cabinet
1 − Refer to reverse−flow coil installation instructions for
correctly sized opening in floor and installation of cabi-
net.
2 − When cooling cabinet is in place, set and secure the
furnace according to the instructions that are provided
with the cooling coil. Secure the furnace to the cabinet.
3 − Seal the cabinet and check for air leaks.
Return Air Opening −− Downflow Units
Return air may be brought in only through the top opening
of a furnace installed in the downflow position.The follow-
ing steps should be taken when installing plenum:
1 − Bottom edge of plenum should be flanged with a
hemmed edge (See figure 11 or 12).
2 − Sealing strips should be used to ensure an airtight seal
between the cabinet and the plenum.
3 − In all cases, plenum should be secured to top of fur-
nace using sheet metal screws.
4 − Make certain that an adequate seal is made.
PLENUM
(Field Provided)
É É É É
SEALING STRIP
(Field Provided)
Side View
FIGURE 11
SUPPLY AIR PLENUM
ADDITIVE BASE
SECURE FROM
OUTSIDE CABINET
CABINET
SIDE PANEL
Page 9
PLENUM
(Field Provided)
É É É É
SECURE FROM
INSIDE CABINET
Side View
FIGURE 12

Filters

This unit is not equipped with a filter or rack. A field−pro-
vided filter is required for the unit to operate properly. Table
3 lists recommended minimum filter sizes.
A filter must be in place when the unit is operating.
NOTE − In upflow applications where side return air fil-
ter is installed on same side as the condensate trap, fil-
ter rack must be installed beyond condensate trap to
avoid interference.
Furnace
Cabinet Size
Side Return
445mm 406 X 635 X 25 (1)
533mm 406 X 635 X 25 (1)
622mm 406 X 635 X 25 (2)

Duct System

Use industry-approved standards to size and install the
supply and return air duct system. This will result in a quiet
and low-static system that has uniform air distribution.
NOTE − Operation of this furnace in heating mode (indoor
blower operating at selected heating speed) with an exter-
nal static pressure which exceeds 200 Pa (0.8 inches w.c.)
may result in erratic limit operation.
Supply Air Plenum
If the furnace is installed without a cooling coil, a removable
access panel should be installed in the supply air duct. The
access panel should be large enough to permit inspection
(either by smoke or reflected light) of the heat exchanger
for leaks after the furnace is installed. If present, this ac-
cess panel must always be in place when the furnace is op-
erating and it must not allow leaks into the supply air duct
system.
Return Air Plenum
Return air must not be drawn from a room where this
furnace, or any other gas appliance (ie., a water heat-
er), is installed. When return air is drawn from a room, a
negative pressure is created in the room. If a gas ap-
pliance is operating in a room with negative pressure, the
flue products can be pulled back down the vent pipe and
SEALING STRIP
(Field Provided)
CABINET
SIDE PANEL
TABLE 3
Filter Size −− mm
Bottom Return
406 X 635 X 25 (1)
508 X 635 X 25 (1)
610 X 635 X 25 (1)