035-17480-000 Rev. A (800)
10
Unitary Products Group
NOTE:The furnace’s control system depends on correct
polarity of the power supply and a proper ground connection.
Refer to the “FURNACE CONTROL DIAGNOSTICS” section
on page 30 for symptoms of reversed power supply polarity.
Connect the power supply as shown on the unit wiring label
on the inside of the blower compartment door. The black fur-
nace lead must be connected to the L1 (hot) wire from the
power supply. The white furnace lead must be connected to
neutral. Also, the green equipment ground wire must be con-
nected to the power supply ground.
Remove the screws retaining the wiring box cover. Route the
power wiring through the opening in the unit into the junction
box with a conduit connector or other proper connection.
Make wiring connections and replace the wiring box cover
and screws. Refer to Figure 6.
An alternate wiring method is to use a field provided 2 x 4 box
and cover on the outside of the furnace. Route the furnace
leads into the box using a protective bushing where the wires
pass through the furnace panel.
NOTE:The power connection leads and wiring box on upflow
units may be relocated to the left side of the furnace. Remove
the screws and cut wire tie holding excess wiring. Reposition
on the left side of the furnace and fasten using holes
provided.
ELECTRICAL CONTROL CONNECTIONS
Install the field-supplied thermostat. The thermostat instruc-
tions for wiring are packed with the thermostat. With the ther-
mostat set in the OFF position and the main electrical source
disconnected, complete the low-voltage wiring from the ther-
mostat to the terminal board on the ignition module. Connect
Class 2 control wiring for single stage thermostat or for two
stage thermostat. (Refer to Figure 7 for single stage and Fig-
ure 8 for two stage.).
NOTE: Some electronic thermostats do not have adjustable
heat anticipators. They may have other type cycle rate adjust-
ments. Follow the thermostat manufacturer's instructions.
The 24-volt, 40 VA transformer is sized for the furnace com-
ponents only, and should not be connected to power auxiliary
devices such as humidifiers, air cleaners, etc.
The transformer may provide power for an air conditioning
unit contactor.
Use copper conductors only.
Set the heat anticipator in the room thermostat as
shown below. Setting it lower will cause short
cycles. Setting it higher will cause the room temper-
ature to exceed the setpoint.
Two-Stage Thermostat
First Stage
.4 Amps
Second Stage
.1 Amps
Single Stage Thermostat
.4 Amps
FIGURE 6 :
Upflow Models (P*ur / Fg9-up / G9t-up)
Electrical Wiring
FIGURE 7 :
Field Wiring For Single Stage Thermostat
FIGURE 8 :
Field Wiring For Two Stage Thermostat
CLASS 2 SYSTEM
CONTROL WIRING
TO THERMOSTAT
L1
(HOT)
N
GRD
BLK
GRN
WHI
WIRING INSIDE
JUNCTION BOX
: BLK/BLK
WHI/WHI
GRN/GRN
BURNER COMPARTMENT
BLOWER COMPARTMENT
DOOR SWITCH
IGNITION MODULE
TRANSFORMER
JUNCTION
BOX
NEUTRALS
EAC
COOL
HEAT
HUM
PARK
PARK
L1
XFMR
Y
WR
G
C
ROOM
THERMOSTAT
FURNACE
CONTROL
24 V COM. (IF REQ)
B
G
Y
C
G
Y
1
SINGLE-STAGE THERMOSTAT CONNECTION DIAGRAM
R
RH
RC
W1
W1
W2
FAN
24 V POWER
COOLING
HEAT
DELAY
TIMER
BLUE
WHITE
TO AIR CONDITIONER
CONDENSING UNIT
ROOM
THERMOSTAT
FURNACE
CONTROL
TO AIR CONDITIONER
CONDENSING UNIT
24 V COMMON
B
*
G
Y
C
G
Y
1
TWO-STAGE THERMOSTAT CONNECTION DIAGRAM
R
RH
RC
W1
W2
W1
W2
FAN
24 V POWER
COOLING
HEAT (LOW)
HEAT (HIGH)
*
Remove wires (blue & white) from timer
DELAY
TIMER
BLUE
WHITE
