GM9S80 Installation Manual
16
One of the most common causes of a problem in a forced
cause premature heat exchanger failure.
A new home may require more frequent replacement until all
construction dust and dirt is removed.
Upflow Models Minimum Recommended Filter Size
*0403A* 1 - 16 X 25 Side or 1 - 14 X 24 Bottom Return
*0603A* 1 - 16 X 25 Side or 14 X 24 Bottom Return
*0603B* 1 - 16 X 25 Side or Bottom Return
*0604B* 1 - 16 X 25 Side or Bottom Return
*0803B* 1 - 16 X 25 Side or Bottom Return
*0804B* 1 - 16 X 25 Side or Bottom Return
*0804C* 1 - 16 X 25 Side or Bottom Return
*0805C*
1 - 16 X 25 Side or Bottom Return¹
*1005C* 2 - 16 X 25 Side or 1 - 20 X 25 Bottom Return¹
*1205D* 2 - 16 X 25 Side or 1 - 24 X 24 Bottom Return¹
Downflow Models
*0403A* 2 - 10 X 20 or 1 - 14 X 25 Top Return
*0603A* 2 - 10 X 20 or 1 - 14 X 25 Top Return
*0804B* 2 - 14 X 20 or 1 - 16 X 25 Top Return
*0805C* 2 - 14 X 20 or 1 - 20 X 25 Top Return
*1005C* 2 - 14 X 20 or 1 - 20 X 25 Top Return
¹ = Use 2 - 16 X 25 filters and two side returns or 20 X 25 filter on
bottom return if furnace is connected to a cooling unit over 4 tons
nominal capacity
Larger filters may be used, filters may also be centrally located
A combination of one side & bottom may be used instead of both sides
Wiring routing must not interfere with circu-
Low voltage connections can be made through either the
right or left side panel. Thermostat wiring entrance holes
shows connections for a “heat/cool system”.
-
-
agram, located on the blower compartment door, for further
Y
C
Y
C
G
R
W
Y2
Y/Y1
C
G
R
W
ROOM THERMOSTAT
INTEGRATED FURNACE
CONTROL MODULE
REMOTE COOLING UNIT
(SINGLE STAGE)
Thermostat - Single-Stage Heating with Single-Stage Cooling
Y1
C
Y1C
G
R
W
Y2
Y/Y1
C
G
R
W
ROOM THERMOSTAT
INTEGRATED FURNACE
CONTROL MODULE
REMOTE COOLING UNIT
(TWO STAGE)
Y2
Y2
Thermostat - Single-Stage Heating with Two-Stage Cooling
This furnace can be used in conjunction with a heat pump
in a fossil fuel application. A fossil fuel application refers to
a combined gas furnace and heat pump installation which
uses an outdoor temperature sensor to determine the most
A heat pump thermostat is required to properly use a sin-
gle-stage furnace in conjunction with a heat pump. Refer to
the fossil fuel kit installation instructions for additional ther-
mostat requirements.
Strictly follow the wiring guidelines in the fossil fuel kit instal-
lation instructions. All furnace connections must be made
to the furnace two-stage integrated control module and the
Two furnaces of the same model may be twinned. The in-
tegrated control board has a 3/16” terminal labeled “TWIN”
located beside the low voltage thermostat connection strip.
Twinning allows simultaneous operation of two furnaces and
forces the indoor blower motors of each furnace to operate
-
external kits or parts. The staging and speed tap options
must be set the same on both furnaces.
power supply. The L1 connection to each furnace must be in
service panel phase leg). To verify that the furnaces are in
phase, check from L1 to L1 on each furnace with a voltme-
ter. If the furnaces are in phase, the voltage between both
furnaces will be .