START

STAGE 1

TRIAL FOR

IGNITION

THERMOSTAT (CONTROLLER) CALLS FOR HEAT

SPARK GENERATOR POWERED

First valve (pilot) operator opens

PILOT BURNER OPERATION

Pilot burner lights.

Pilot burner does not light

Module senses

Module

 

Response

 

flame current.

S-8600M

 

After 15 sec. ignition

 

 

 

shut-down. 5 minute

 

 

 

time delay before re-try.

 

 

 

 

 

S-8600H

 

After 15 sec. ignition

 

 

 

system locks out

 

 

 

must be manually reset.

STAGE 2

MAIN BURNER

OPERATION

FLAME CURRENT SENSED

Spark generator off.

Second valve operator (main) opens.

MAIN BURNER OPERATION

Module monitors pilot flame current.

POWER INTERRUPTION System shuts off, restarts when power is restored.

PILOT FLAME FAILURE Main valve closes. Module starts trial for ignition.

END

THERMOSTAT (CONTROLLER) SATISFIED Valves close, pilot and main burners are off.

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A.O. Smith HW 610 warranty Stage Main Burner Operation Flame Current Sensed