46
P/N 470880
Rev. K 5-31-06
DESCRIPTION OF OPERATION
1. Set the thermostat to the lowest setting.
2. Push the power switch off. The electric power supply requirement is: • 115 volts 60 Hz, 1 Ph, 1.5 Amp
3. Remove the door.
4. Push in the gas control knob slightly and turn clockwise to “OFF”.
5. Wait (5) minutes to clear out any gas. If you then smell gas
STOP
. Follow the safety information.
If you do not smell gas, go to the next step.
6. Turn the knob on the gas control counterclockwise
to “ON”.
7. Replace the door.
8. Make sure the pump is running and is primed.
9. Push the power switch on.
10. Set the thermostat to the desired setting.
NOTE
Ignition system in this product equipped with a 24 VAC microprocessor based proven current hot
surface ignition system designed to monitor and control gas function in appliances operating between
400,000 and 2,500,000 BTU’s.
11.
Heat Mode:
When a call for heat is received from the thermostat by applying 24 VAC to TH/W terminal,
the control will check the pressure switch for normally open contacts. If a pressure switch signal is seen at the
start of the heat mode, program execution stops and the control will allow sixty seconds for the pressure
switch signal to disappear before entering a soft lockout fault state.
If no pressure switch signal is seen (or subsequently disappears), the combustion fan output is powered, the
HSI element is powered after a 15 second delay and supervision of the input voltage, proof of current
detector and gas valve relay contacts starts.
When flame is detected during trial for ignition, the hot surface element de-energizes, the combustion blower
and gas valve remain powered, and the thermostat, pressure switch and flame sense are monitored by the
microprocessor to assure system integrity.
When the thermostat is satisfied and the demand for heat ends, the main valve is de-energized immediately, the
control senses the loss of flame signal and initiates the post-purge period before de-energizing the combustion
blower.
If, during any sequence, an erroneous flame is detected, the combustion blower is energized and all other
function and monitor states (except flame sense) are de-energized. When erroneous flame is no longer
detected, the system will revert to stand-by after the post-purge period.
Hard Lockout - Failure to Light:
Should the main burner fail to light, or flame is not detected during the
trial for ignition period, the control will go into hard lockout. During this sequence, the thermostat and pressure
switch will
not
be monitored, the flame sense and reset input will be the fault and 24 VAC being applied to the
reset input, the control will go to the Power-up/ Stand-by state.
Soft Lockout:
System faults causing soft lockout are: Pressure switch not established during trial for ignition,
pre-purge stall due to improper input voltage and unproven element current. During this sequence, the
thermostat and flame sense will be monitored, the pressure switch and reset input will not be monitored and
the fan output will be turned off. Upon resolution of the fault(s) and completion of the microprocessor’s
programmed reset delay, the control will go to the Power-up/Stand-by state.
A-22
Low NOx (contd.)
