State SBD85 365NE A - Manual (Page 26)

26
seQuence of operation flow chart
Description of this flow chart can be found in the “SEQUENCE OF OPERATION” section found on page 25.
flow chart 1.
A
A
IDLE
(NOT POWERED)
“CALL FOR HEAT”
RECEIVED FROM
THERMOSTAT
POWER TO
MODULE AND
SELF CHECK
TRIAL FOR
IGNITION
(TIMER STARTED)
FLAME
PROVED?
CLOSE PILOT
GAS VALVE
SPARK OFF
(BEFORE TRIAL FOR IGNITION TIMER EXPIRES)
SPARK OFF
OPEN MAIN GAS
VALVE
FLAME
STABILIZATION
(2 SECONDS)
RUN
NO
NO
NO
YES
YES
YES
“CALL
FOR HEAT”
ENDS?
FLAME
LOST?
CLOSE MAIN GAS
VALVE AND PILOT
GAS VALVE
CLOSE MAIN GAS
VALVE AND PILOT
GAS VALVE
SPARK ON
OPEN PILOT GAS
VALVE
RETRY DELAY
(5 MINUTES)
WAIT FOR
“CALL FOR HEAT”
TO BE REMOVED
ACTIVATE ALARM
CONTACT(S)
(OPTIONAL)
RETRY OR
LOCKOUT
MODEL?
LOCKOUT
RETRY