26
1. Heating thermostat controller wiring
a. Two stage heating: (see Figure 22):
Programmable controller thermostat for
the two stage heating should be wired as
wiring diagram shown in Figure 22. On
a call for fi rst stage heat, inducer runs
for 30 seconds pre-purge at high speed.
The furnace will operate on low fi re and
both the inducer and main blower will
operate at low speed. On a call second
stage heat based on programmed timing
or differential temperature, the furnace will
operate at high fi re and both inducer and
main blower will operate at high speed.
b. Low fi re only operation: To set low fi re
only operation, program the second stage
temperature higher than the desired room
temperature (refer to Thermostat control-
ler Instructions). If the furnace is operated
permanently at low stage, disconnect
the yellow wire on the “W2” terminals
between the furnace add-on board and
the interface board. (See Figure 24).
c. Outdoor Thermostat Function:
If available on controller program.
2. Cooling controller thermostat wiring:
(see Figure 23, 25 and cooling wiring dia-
gram).
Once fi eld wired for heating, Connect “R”
and “C” black wires on the Interface control
board to the two black wires from the outdoor
unit contactor (see Figure 23). Also connect
DX+ DX- and GRD terminals between the
Interface board and the outdoor unit inverter
with green, white and black wires as shown
in Figures 23 and 25. Cooling unit operates
at the best optimized condition for the out-
door weather according to program in the
thermostat controller.
The thermostat controller must not be installed
on an outside wall or any other location where
its operation may be adversely affected. Adverse
effects include radiant loading from fi replaces,
sunlight, or lighting fi xtures, and convective
loading from warm air registers or electrical
appliances.
START-UP AND ADJUSTMENTS
Prior to start-up, verify that:
1. The line voltage power leads are securely
connected, that the polarity of the con-
nections is correct, and that the furnace is
properly grounded.
2. The thermostat wires (A, B, C and R) are
securely connected to the correct leads on
the terminal strip of the interface board. (R,
DX+, DX- and Gnd. (See Figure 22.)
3. The gas line service pressure does not
exceed 10.0 in. water column (0.36 psig),
and is not less than 4.5 in. water column
(0.16 psig) for natural gas. For LP gas the
line service pressure must not exceed 14
in. water column (0.51 psig), and must not
be less than 11.0 in. W.C. (0.40 psig).
4. The roll-out and vent safety manual reset
switches are closed. If necessary, press the
red button to reset a switch. See Figure 26
for location. DO NOT install a jumper wire
across a switch to defeat its function. If a
switch reopens on start-up, DO NOT reset
the switch without identifying and correcting
Field Supplied Disconnect
Within Sight of Furnace
Field Supplied
Panel Connector
Field Supplied
Fused Service
Panel
Black (Hot)
White (Neutral)
Green or Bare
(Ground)
Black
White
Black
White
Black
White
Field Line Voltage
Wiring
Factory Line
Voltage Wiring
Ground
Ground
Ground
Junction Box (may be internal
or external to the furnace). These
connections can be made in the
field supplied disconnect at the
furnace.
Figure 21. Line Voltage Field Wiring
