Verifying Burner Operation; Verifying Operation Of The Supply Air Limit Switch - Nordyne TC Series User Manual

2-STAGE GAS VALVES
HI Input
Adjusting Screw
Inlet
Pressure
Tap
Model VR8205Q2381
ON / OFF
Switch
Manifold
pressure
Tap
Model VR9205Q1028
Figure 27. HI & LO Input Adjusting Screws
2. Adjust all registers and duct dampers to the desired
position and run the furnace for 10 to 15 minutes in
high fire before taking any temperature readings. The
temperature rise is the difference between the supply
and return air temperatures.
For typical duct systems, the temperature rise will fall
within the limits specified on the rating plate with the
blower speed at the factory recommended setting. If
the measured temperature rise is outside the specified
limits, it may be necessary to change the speed of the
blower. NOTE: Lowering the blower speed increases the
temperature rise and a higher blower speed will decrease
the temperature rise.
The furnace is equipped with a multi-speed motor. Heating
and cooling speed selection is made by moving the
switches on the integrated control located in the furnace.
Lo Input
Adjusting Screw
Manifold
pressure
Tap
ON
OFF
ON / OFF
Knob
HI Input
Lo Input
Adjusting
Adjusting
Screw
Screw
Inlet
Pressure
Tap

Verifying Burner Operation

CAUTION:
The door over the burners may only be open
for inspection purposes only.The door must be
installed during unattended operation.
1. Remove the burner compartment door.
2. Set the thermostat above room temperature and observe
the ignition sequence. The burner flame should carry
over immediately between all burners without lifting off,
curling, or floating. The flames should be blue, without
yellow tips.
3. After validating fl characteristics, change thermostat
setting to below room temperature.
4. Verify burner flame is completely extinguished.
5. Replace the burner compartment door.
Verifying Operation of the Supply Air Limit
Switch
A properly functioning limit switch should turn off the gas
valve when the return is blocked (time depends on how
well the return air is blocked). The circulating air and
combustion blowers should continue to run when the
limit switch opens.
1. Check the blower door for secure mounting and that
there is power to the furnace.
2. Block the return airflow to the furnace by installing a
close-off plate in place of or upstream of the filter(s).
3. Set the thermostat above room temperature and observe
the Operating Sequence.
4. Remove the close-off immediately after the limit switch
opens. If the furnace continues to operate with no return
air, set the thermostat below room temperature, shut off
the power to the furnace, and replace the limit switch.
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