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SEQUENCE OF OPERATION - IGNITION CONTROL
1.
POWER-UP
Power is applied to the full time 24 volt input. The microprocessor will start a self-check routine of about five
seconds. After this delay, the LED will come on and the control is ready to start a new call for heat.
For Manual Reset Button Models Only
Models of the 35-67 with non-volatile lockout (manual reset button), the microprocessor will check memory to
determine if the control should remain in lockout.
Lockout Present: The lockout indicator output will turn on, and the LED will repeatedly flash three times. To reset
the control, push the Reset Button.
Not in Lockout: The control is ready to start a new call for heat.
2.
CALL FOR HEAT
The thermostat is turned on. The combustion fan relay will turn on.
Proof of Pressure Switch: The control will look for a signal from the pressure switch, indicating that the fan has
come on.
Pre-Purge Delay: When the pressure switch signal is seen, the pre-purge delay will start. The pre-purge indicator
output will turn on.
3.
HEAT-UP
After the pre-purge delay, power will be applied to the hot surface ignition element. The pre-purge indicator will
turn off.
Current Proving: The 35-67 will monitor the current through the ignition element. When the current reaches a
pre-determined level, the LED will flash once.
Dwell Time: From the point when the current has been proven, there will be a delay called dwell time. Dwell time
assures that the ignition element has sufficient time to reach ignition temperature.
4.
IGNITION
When dwell time is completed, the gas valve will open. The ignition element will turn off 2 seconds before the end
of the ignition period.
No Flame:
Single Trial for Ignition Models - The control will go to post-purge, and then lockout.
Three Trials for Ignition Models - The control will make two additional purge/heat-up/ignition cycles. If a flame is
not proven, the control will go to post-purge, and then lockout.
Flame is Proven:
The gas valve will remain on beyond the normal ignition period. This continues as long as signals are present for
the flame, thermostat and pressure switch.
Post-Purge: After all ignition cycles are complete, the control will enter post-purge. The combustion fan will
remain on.
Lockout: After post-purge is complete, the combustion fan will turn off. The Lockout Indicator output will turn on.
The LED will repeatedly flash three times.
5.
LOSS OF FLAME SIGNAL
The gas valve will turn off. Depending on the model chosen:
Single Trial for Ignition Models - A new trial for ignition cycle will start.
Three Trials for Ignition Models - Three new ignition cycles will start.
CONTROL PANEL INDICATING LIGHTS
The control panel has an ON/OFF power switch with indicating light and five (5) indicating lights to show operation
and control sensed malfunctions.
OPERATING CONTROL INDICATING LIGHTS
Indicating Lights
Call for Heat
Lockout
Flame
Blower
Water Flow
FUNCTION
Operating control has enabled the burner control to begin the ignition sequence.
Ignition module unable to properly prove ignition.
Burner is operating
Blower is running
Water flow rate meets the minimum threshold of the flow switch
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34-50 04/02/2010
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