Verifying Burner Operation; Verifying Operation Of Over-Temperature Limit Control; Component Functions; Flame Sensor - Nordyne R4GD Series Installation Instructions Manual

specified, it may be necessary to change the blower speed.
Lower blower speeds will increase the temperature rise and
higher blower speeds will decrease the temperature rise.
The unit is equipped with a multi-speed motor. Heating and
cooling speed selection is made by moving the leads on the
integrated control located in the unit control box. The wiring
diagram on the unit and in Figure 10 show the speed taps
for adjusting motor speed. Refer to the Blower Speed
Section of this installation instruction for more details.
The integrated control is designed to start the circulating air
blower 30 seconds after the gas valve is opened. The
integrated control is factory wired to turn the blower motor
off 120 seconds after the gas valve is closed.
Verifying Burner Operation — To verify operation of the
burners remove the louvered control access panel to
ensure there is power to the unit. Set the thermostat to a
temperature above room temperature and observe the
ignition sequence. The burner flame should carry over
immediately between all burners. The flames should be
blue, without yellow tips. Flames should extend from each
burner without lifting off, curling, or floating. After verifying
satisfactory flame characteristics, set the thermostat to a
temperature below room temperature and verify that the
burner flame extinguishes completely.
! WARNING:
Uninsulated live components are exposed when
louvered control access panel is removed.
Verify Operation of Over-Temperature Limit Control –
To verify operation of the over-temperature limit control,
make sure that the louvered control access panel is in
place and that there is power to the unit. Block the return
airflow to the unit by installing a close-off plate in place of
or upstream of the filter. Set the thermostat to a temperature
above room temperature and verify the unit operates with
the correct sequence of operation (see page 25). The over-
temperature limit control should function to turn off the gas
valve within approximately four minutes (the exact time
depending on the efficiency of the close-off in blocking the
return air to the unit). The circulating air and combustion
blowers should continue to run when the over-temperature
limit control switch opens. Remove the close-off immediately
after the over-temperature limit control opens. If the unit
operates for more than four minutes with no return air, set
the thermostat to a temperature below room temperature,
shut off the power to the unit, and replace the over-
temperature limit control.

COMPONENT FUNCTIONS

Flame Sensor — The flame sensor acts to prove that
flame has carried over from the ignitor to the right-most
burner. If no flame is sensed, the unit will be shut down
automatically.
Flame Roll-Out Control — The flame roll-out control acts
to verify that the burner flame is being drawn into the heat
exchanger tubes. If the burner flame is not being drawn into
the heat exchanger tubes, the roll-out control will open
within several seconds and the integrated control diagnostic
light will flash one time. The circulating air blower and
combustion blower will continue to operate if the flame roll-
out control opens.
Gas Valve — The gas valve acts to control the flow of gas
to the burners. When the gas valve is energized it
automatically opens and regulates the gas pressure in the
manifold.
Pressure Switch — The pressure switch acts to verify that
the inducer motor is drawing the combustion gases through
the heat exchanger tubes and venting the gases through
the vent system.
Over-Temperature Limit Control — The over-temperature
limit control acts to prevent the air temperature leaving
the unit from exceeding the maximum outlet air
temperature. If the limit opens, the integrated control
diagnostic will flash one time. The circulating air blower
and combustion blower will continue to operate if the
over-temperature limit control opens.

UNIT MAINTENANCE

! WARNING:
To avoid risk of electrical shock, personal injury,
or death, disconnect all electrical power to the
unit before performing any maintenance or
service. The unit may have more than one
electrical supply.
! CAUTION:
Use care when removing parts from this unit.
Personal injury can result from sharp metal edges
present in all equipment of sheet metal
construction.
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