25613-0-0309Page 52
SparkGenerator Powered
FirstValve (Pilot)
OperatorOpens
Pilotburner lights.
Modulesenses flame current.
PILOT BURNER OPERATION
MODULE
S8600H
*Lockout timing is stamped on module.
RESPONSE
After90 seconds*pilot valve
closes,spark stops.
OR
IFFLAME CURRENT SENSED
Sparkgenerator off
Secondvalve operator
(Main)opens.
MAINBURNER OPERATION
Modulemonitors pilot
flamecurrent.
THERMOSTATSATISFIED
Valvesclose. Pilot and
mainburners are off.
START
STAGE1
Trialfor Ignition
STAGE2
MainBurner
Operation
END
S8600H NORMALOPERATING SEQUENCE
Pilotburner does not light
Thermostat,Wall Switch,
Remote,Etc. Calls for Heat
POWERINTERRUPTION
Systemshuts off. Restarts when
poweris restored.
PILOTFLAME FAILURE
Secondmain operator closes.
Modulestarts trial for ignition.
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
rst main valve operator and closes the rst main valve in the gas
control, stopping pilot gas ow. 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 ame is established, a ame rectication circuit
is completed between the sensor and burner ground. The ame
sensing circuit in the module detects the ame current, shuts off the
spark generator and energizes the second main valve operator. The
second main valve opens and gas ows to the main burner, where
it is ignited by the pilot burner. The ame 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.
CAUTION: Label all wires prior to disconnection when
servicing controls. Wiring errors can cause improper and
dangerous operation. Verify proper operation after servicing.
INTERMITTENT PILOT TROUBLESHOOTING (continued)