Installation & Operating Manual

Bobcat Models B-120A and B-200A
36
THERMOSTAT CALLS FOR HEAT
CIRCULATOR(S) ON
5 SECOND PRE-PURGE PERIOD
BOBCAT BOILER MODELS B-120 and B-200 SEQUENCE OF OPERATION
BLOWER SPEED CONFIRMED?
GAS VALVE OPENS
GAS VALVE REMAINS OPEN. CONTROL
CONTINUOUSLY MONITORS
THERMOSTAT, HIGH LIMIT, WATER
SENSORS, BLOWER SPEED, FLAME
SIGNAL, AND LWCO (IF USED).
THERMOSTAT CALL FOR HEAT ENDS
GAS VALVE CLOSES
10 SECOND BLOWER POST PURGE.
15 SECOND CIRCULATOR POST PURGE.
CONTROL LOCKOUT
DISPLAY SHOWS
ERROR “A 33”
YES
NO
NO
COMBUSTION BLOWER ON
(AT MEDIUM SPEED)
TRIAL FOR IGNITION - 6 SECONDS
SPARK IGNITOR ENERGIZED
WATER HIGH LIMIT CLOSED?
YES
GAS VALVE REMAINS OPEN
FOR 4 SECONDS
SPARK IGNITOR DE-ENERGIZED
FLAME SIGNAL SENSED?
YES
3 TRIALS FOR
IGNITION
WITH NO FLAME SENSED?
2 TIMES RETRIALS
FOR IGNITION
GAS VALVE CLOSED.
BLOWER POST PURGE
10 SECONDS.
NO
CONTROL LOCKOUT
DISPLAY SHOWS
ERROR “A 01”
YES
CONTROL LOCKOUT
DISPLAY SHOWS
ERROR “A 03”
NO