13281-9-0709
Page 16
TRIAL FOR IGNITION
Pilot Ignition
Following call for heat (system start on S8600H), the module
energizes the first main valve operator. The first main valve opens,
which allows gas to flow to the pilot burner. At the same time, the
electronic spark generator in the module produces a 13,000 volt
spark pulse output (at 25 pf load). The voltage generates a spark
at the igniter-sensor that lights the pilot.
If the pilot does not light, or the pilot flame current is not at least
1.0 ua and steady, the module will not energize the second main
valve and the main burner will not light.
Safety Lockout
S8600H provides 100 percent shutoff, or safety lockout. a timer
starts timing the moment the trial for ignition starts. Ignition spark
continues only until the timed trial for ignition period ends. Then
the module goes into safety lockout. Lockout de-energizes the
first main valve operator and closes the first main valve in the gas
control, stopping pilot gas flow. The control system must be reset
by setting the thermostat below room temperature for one minute
or by turning off power to the module for one minute.
Main Burner Operation
When the pilot flame is established, a flame rectification circuit
is completed between the sensor and burner ground. The flame
sensing circuit in the module detects the flame current, shuts off the
spark generator and energizes the second main valve operator. The
second main valve opens and gas flows to the main burner, where
it is ignited by the pilot burner. The flame current also holds the
safety lockout timer in the reset (normal) operating condition.
When the call for heat ends, both main valve operators are de-
energized, and both main valves in the gas control close.
START
STAGE 1
TRIAL FOR IGNITION
STAGE 2
MAIN BURNER
OPERATION
END
THERMOSTAT
CALLS FOR HEAT
SPARK GENERATOR POWERED
FIRST VALVE (PILOT)
OPERATOR OPENS
PILOT BURNER OPERATION
PILOT BURNER LIGHTS
MODULE SENSES FLAME CURRENT.
PILOT BURNER DOES NOT LIGHT
OR
MODULE
RESPONSE
S8600H
AFTER 90SECONDS *PILOTVALVE
CLOSES, SPARK STOPS
*LOCKOUT TIMING IS STAMPED ON MODULE
IF FALME CURRENT SENSED
*SPARK GENERATOR OFF
*SECOND VALVE OPERATOR
(MAIN) OPENS.
MAIN BURNER OPERATION
MODULE MONITORS PILOT
FLAME CURRENT
THERMOSTAT SATISFIED
VALVES CLOSE.
PILOT AND MAIN BURNERS ARE OFF.
POWER INTERRUPTION
SYSTEM SHUT OFF. RESTARTS WHEN
POWER IS RESTORED.
PILOT FLAME FAILURE
SECOND MAIN OPERATOR CLOSES
MODULE STARTS TRIAL FOR IGNITION.
START
STAGE 1
TRIAL FOR IGNITION
STAGE 2
MAIN BURNER
OPERATION
END
THERMOSTAT
CALLS FOR HEAT
SPARK GENERATOR POWERED
FIRST VALVE (PILOT)
OPERATOR OPENS
PILOT BURNER OPERATION
PILOT BURNER LIGHTS
MODULE SENSES FLAME CURRENT.
PILOT BURNER DOES NOT LIGHT
OR
MODULE
RESPONSE
S8600H
AFTER 90SECONDS *PILOTVALVE
CLOSES, SPARK STOPS
*LOCKOUT TIMING IS STAMPED ON MODULE
IF FALME CURRENT SENSED
*SPARK GENERATOR OFF
*SECOND VALVE OPERATOR
(MAIN) OPENS.
MAIN BURNER OPERATION
MODULE MONITORS PILOT
FLAME CURRENT
THERMOSTAT SATISFIED
VALVES CLOSE.
PILOT AND MAIN BURNERS ARE OFF.
POWER INTERRUPTION
SYSTEM SHUT OFF. RESTARTS WHEN
POWER IS RESTORED.
PILOT FLAME FAILURE
SECOND MAIN OPERATOR CLOSES
MODULE STARTS TRIAL FOR IGNITION.
START
STAGE 1
TRIAL FOR IGNITION
STAGE 2
MAIN BURNER
OPERATION
END
THERMOSTAT
CALLS FOR HEAT
SPARK GENERATOR POWERED
FIRST VALVE (PILOT)
OPERATOR OPENS
PILOT BURNER OPERATION
PILOT BURNER LIGHTS
MODULE SENSES FLAME CURRENT.
PILOT BURNER DOES NOT LIGHT
OR
MODULE
RESPONSE
S8600H
AFTER 90SECONDS *PILOTVALVE
CLOSES, SPARK STOPS
*LOCKOUT TIMING IS STAMPED ON MODULE
MAIN BURNER OPERATION
MODULE MONITORS PILOT
FLAME CURRENT
THERMOSTAT SATISFIED
VALVES CLOSE.
PILOT AND MAIN BURNERS ARE OFF.
POWER INTERRUPTION
SYSTEM SHUT OFF. RESTARTS WHEN
POWER IS RESTORED.
PILOT FLAME FAILURE
SECOND MAIN OPERATOR CLOSES
MODULE STARTS TRIAL FOR IGNITION.
IF FLAME CURRENT SENSED
*SPARK GENERATOR OFF
*SECOND VALVE OPERATOR
(MAIN) OPENS
After 90 seconds* pilot valve
closes, spark stops
.
