508145-01
Issue 2128
Page 31 of 36
Other Unit Adjustments
Primary and Secondary Limits
The primary limit is located on the heating compartment
vestibule panel. The secondary limits (if equipped) are
located in the blower compartment, attached to the back
side of the blower. These auto reset limits are factory-set
and require no adjustment.
Flame Rollout Switches
This manually reset switches are located on the baffle
plate in the burner assembly.
Pressure Switch
The pressure switch is located in the heating compartment
adjacent to the combustion air inducer. The switch checks
for proper combustion air inducer operation before allowing
ignition trial. The switch is factory-set and requires no
adjustment.
Temperature Rise
After the furnace has been started, and supply and return
air temperatures have been allowed to stabilize, check
the temperature rise. If necessary, adjust the blower
speed to maintain the temperature rise within the range
shown on the unit nameplate. See Table 17 for allowable
heating speeds.Increase the blower speed to decrease
the temperature. Decrease the blower speed to increase
the temperature rise. Failure to adjust the temperature rise
may cause erratic limit operation.
Electrical
1. Check all wiring for loose connections.
2. Check for the correct voltage at the furnace (furnace
operating). Correct voltage is 10%.
3. Check amp-draw on the blower motor with inner
blower panel in place.
Unit Nameplate__________Actual__________
Blower Speeds
Follow the steps below to change the blower speeds.
1. Turn off electrical power to furnace.
2. Remove blower access panel.
3. Disconnect existing speed tap at integrated control
speed terminal.
NOTE:
Termination of any unused motor leads must
be insulated.
4.
Place unused blower speed tap on integrated control
“PARK” terminal or insulate.
5. Refer to blower speed selection chart on unit wiring
diagram for desired heating or cooling speed. See
Blower performance data at the end of this manual
and Table 17 for allowable heating speeds.
6.
Connect selected speed tap at integrated control
speed terminal.
7. Resecure blower access panel.
8. Turn on electrical power to furnace.
9. Recheck temperature rise.
Heating Sequence of Operation
Electronic Ignition
The two-stage, variable speed integrated control used
in 80G2DFE
units has an added feature of an internal
Watchguard control. The feature serves as an automatic
reset device for ignition control lockout caused by ignition
failure. After one hour of continuous thermostat demand
for heat, the Watchguard will break and remake thermostat
demand to the furnace and automatically reset the control
to begin the ignition sequence.
NOTE:
The ignition control thermostat selection DIP switch
is factory-set in the “TWO-STAGE” position.
Applications Using a Two-Stage Thermostat
A - Heating Sequence -- Integrated Control Thermostat
Selection DIP Switch 1 OFF in “Two-Stage” Position
(Factory Setting)
1. On a call for heat, thermostat first-stage contacts
close sending a signal to the integrated control. The
integrated control runs a self-diagnostic program and
checks high temperature limit switches for normally
closed contacts and pressure switches for normally
open contacts. The combustion air inducer is energized
at low speed.
2. Once the control receives a signal that the low pressure
switch has closed, the combustion air inducer begins a
15-second pre-purge in low speed.
NOTE:
If the low fire pressure switch does not close
the combustion air inducer will switch to high fire. After
a 15 second pre-purge the high fire pressure switch
will close and the unit will begin operation on high fire.
After 10 to 20 seconds of high fire operation the unit
will switch to low fire.
3. After the pre-purge is complete, a 20-second initial
ignitor warm-up period begins. The combustion air
inducer continues to operate at low speed.
4. After the 20-second warm-up period has ended, the
gas valve is energized on low fire (first stage) and
ignition occurs. At the same time, the control module
sends a signal to begin an indoor blower 30-second
ON-delay. When the delay ends, the indoor blower
motor is energized on the low fire heating speed, the
HUM contacts close energizing the humidifier and
120V ACC terminal is energized. The furnace will
continue this operation as long as the thermostat has
a first-stage heating demand.
