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Y8610U INTERMITTENT PILOT RETROFIT KIT
68-0291—03 16
7. Perform a gas leak test in the appliance including both
the inlet and outlet sides of the gas control.
GAS LEAK TEST:
Paint the gas control gasket edges and all pipe
connections downstream of the gas control, including the
pilot tubing connections, with a rich soap and water
solution. Bubbles indicate gas leaks. Tighten the joints
and screws or replace component to stop gas leak.
Recheck with soap and water solution.
8. Turn the thermostat or controller below the room temper-
ature. Make sure the main burner and pilot flames go
out.
OPERATION
Fig. 19 summarizes the normal operating sequence for
installations without vent dampers. The ignition control
module’s operation can be conveniently divided into two
phases.
• Trial for pilot ignition
• Main burner operation
Trial for Pilot Ignition
On a “Call for Heat”, the ignition control module energizes the
spark source and the pilot valve relay simultaneously. The pilot
valve opens, allowing gas to flow to the pilot burner for the
ignition trial time. The spark lights the pilot flame when pilot gas
is present. A flame rectification circuit confirms the presence of
the pilot flame, shuts off the spark source, and energizes the
main valve relay.
The ignition control module uses a two-level pilot flame proving
sequence. When a sufficient flame current is sensed, the spark
is turned OFF. However, the pilot flame must generate a higher
level of flame current to energize the main valve. This
approach assures a stable pilot flame to support reliable burner
lightoff. If the pilot flame is weak or unstable, the spark may
turn back ON. However, the trial for pilot ignition will not exceed
the stated ignition trial time.
Main Burner Operation
When the main valve opens, gas flows to the main burner
where it is lit by the pilot flame. There is a short flame
stabilization period as the main valve opens to allow the pilot
flame to stabilize as the main gas lights. The system is now in
the run mode with the presence of the pilot flame continuously
monitored by the flame rectification circuit. If the pilot flame
goes out, the ignition control module senses loss of pilot flame
and shuts off both the pilot valve relay and the main valve
relay. Flow of gas to pilot and main burners stops as the valves
close (100% shutoff).
Failed Trial for Pilot Ignition
The S8610U control module provides multiple trials for ignition
(TFI). If the pilot is not lit or sensed before the end of the trial
for ignition time, the ignition control shuts off the spark and pilot
gas (100% shutoff). There is a five minute delay before another
TFI is initiated. The pattern of TFI followed by a five minute
delay continues until the pilot lights and is proved or the “Call
for Heat” ends. The five minute delay time can be bypassed by
cycling the system thermostat or removing and restoring
system power.
Fig. 19. Normal operating sequence without vent damper.
OPERATING SEQUENCE
“CALL FOR HEAT”
RECEIVED FROM
THERMOSTAT
POWER TO
MODULE AND
SELF CHECK
IDLE
(NOT POWERED)
RUN
YES
TRIAL FOR
IGNITION
(TIMER STARTED)
SPARK ON
OPEN PILOT GAS
VALVE
FLAME
PROVED?
FLAME
STABILIZATION
(2 SECONDS)
YES
NO
RETRY
OPEN MAIN GAS
VALVE
CLOSE
MAIN GAS
VALVE
AND PILOT
GAS VALVE
FLAME
LOST?
NO
CLOSE PILOT
GAS VALVE
SPARK OFF
“CALL
FOR HEAT”
ENDS?
YES
NO
RETRY DELAY
(5 MINUTES)
SPARK OFF
MORE THAN
5 FLAME LOSSES
IN THIS “CALL
FOR HEAT”?
(BEFORE TRIAL FOR IGNITION TIMER EXPIRES)
A
CLOSE MAIN GAS
VALVE AND PILOT
GAS VALVE
B
A
M24903
NO
B
YES