Installer’s Information Manual
Page 17
C22.1 and local codes. Use Type T (63 degrees C rise)
wire or equivalent.
Figure 21. Field Wiring Diagram.
24-VOLT WIRING
Select a location for the room thermostat on a draft-free
interior wall that is away from supply and return air
registers, lights, television, direct sunlight, or other heat
sources.
Install thermostat following field wiring diagram in Figure 21
and thermostat manufacturer's instructions. Thermostat
wire should be 18 AWG wire for best results. NOTE: For
proper cooling operation, "Y" wire must be connected to the
Control. “Y” wire controls cooling speed blower operation.
Set the thermostat's heat anticipator following instructions
provided with the thermostat. This furnace will provide an
820 ohm load for electronic thermostats.
CAUTION: Unapproved 24 VAC accessories that draw
power from the furnace's transformer should not be
installed on this furnace. Addition of such accessories may
cause improper furnace operation and limit transformer life.
SECTION 11. SEQUENCE OF
OPERATION
HEATING MODE
1. Thermostat calls for heat by energizing the “W”
terminal. The control checks to see the limit switch is
closed and pressure switch is open. If pressure switch
is closed, the control will flash “4” and wait indefinitely
for pressure switch to open.
NOTE: If the pressure switch opens (for more than 2
seconds) five times within a single call for heat, the control
will lock out for 1 hour.
2. Draft inducer relay is energized. Draft inducer motor
starts and pressure-switch closes. Control runs
inducer for a 15 second pre-purge time, then proceeds
to the ignition trial period.
NOTE: If the pressure switch does not close within 30
seconds of the inducer energizing, the control will flash “2”
on the LED. The control will leave the inducer energized
indefinitely as long as the call for heat remains and
pressure switch is open.
3. In the ignition trial period, the control energizes the
spark and main gas valve. Inducer remains energized.
If flame is sensed within 7 seconds, spark is de-
energized and control proceeds to heat blower on
delay. If flame is not sensed within 7 seconds, control
de-energizes the gas valve and proceeds with ignition
re-tries (see note below).
4. Control energizes main blower 20 seconds from the
time flame is sensed.
5. When thermostat call for heat is removed, gas control
is de-energized then post-purge and blower off delay
timing begin.
6. Inducer remains on for a 45 second post-purge period
after thermostat is satisfied.
7. Main blower remains energized for 90 to 180 seconds
depending on heating blower off-delay setting.
NOTE: If flame is not established for the first ignition
period, the control de-energizes the gas valve, the inducer
remains energized for 15 seconds. The spark and gas
valve are energized for another trial of ignition. If flame is
not established on the fourth trial for ignition (initial try & 3
re-tries), gas valve is de-energized and goes into lockout.
The control flashes a “1” to indicate failure lockout.
NOTE: If flame is sensed longer than 4 seconds while the
gas valve is de-energized, the control will energize the
inducer and indoor blower on heat speed. The control will
go into lock-out but will still respond to open limit and flame.
The Flame LED will flash rapidly when lock-out is due to
undesired flame.
NOTE: This furnace will not initiate a call for heat or call for
continuous fan while in lock-out. A call for cooling operates
as normal. The control will still respond to an open limit and
undesired flame. Lock-out will automatically reset after 1
hour. The furnace's control can be manually reset by
removing power from the control for more than 1 second or
removing the thermostat call for heat for more than 1 and
less than 20 seconds.
COOLING MODE
Thermostat calls for cooling ("R", "Y" and "G" terminals
connected). Condensing unit contactor closes, energizing
condensing unit. Control energizes main blower on cooling
speed after a 6 second delay. After thermostat is satisfied,
condensing unit contactor is de-energized. Main blower
remains energized for 45 seconds.
