Bryant BW9, Installation, Start-Up, And Operating Instructions Manual

Page: 33 / 52

Fig. 25—Safety Sequences During Operation
A00315
IF DRAFT INDUCER TEMPERATURE REACHES
TEMPERATURE SAFETY SWITCH SETPOINT,
SAFETY SWITCH CONTACTS OPEN IMMEDIATELY
CLOSING GAS VALVE. (LIGHT GOES OUT)
CASTING TEMPERATURE SAFETY SWITCH
CONTACTS WILL OPEN BREAKING 24 VOLT POWER
TO IBC. POWER INDICATOR LIGHT GOES OUT.
REQUIRES MANUAL RESET TO RE-CLOSE
CONTACTS (LIGHT GOES OUT)
POWER LIGHT GOES OUT.
IF BOILER WATER TEMPERATURE REACHES
HI LIMIT (AQUASTAT) SETPOINT, HI LIMIT
N.C. CONTACTS OPEN IMMEDIATELY,
CLOSING GAS VALVE. (VALVE LIGHT GOES OUT)
IF AN ESTABLISHED FLAME SIGNAL IS LOST
WHILE CONTROL EXPECTS THAT THE BURNER
IS OPERATING, CONTROL WILL IMMEDIATELY
DE-ENERGIZE GAS VALVE. (VALVE LIGHT GOES OUT)
CONTROL WILL ATTEMPT TO RE-LIGHT BOILER
3 TIMES. IF FLAME IS NOT PROVEN. CONTROL
LOCKOUT - PROBLEM ESTABLISHING A FLAME
SIGNAL. VALVE LIGHT BLINKS.
IF COMBUSTION AIRFLOW IS LOST WHILE BURNER
IS FIRING ( DIFFERENTIAL AIR PRESSURE
SWITCH CONTACTS OPEN) GAS VALVE WILL
BE DE-ENERGIZED. (VALVE LIGHT GOES OUT)
IF AIR FLOW DOES NOT RE-ESTABLISH
CONTROL LOCKOUT - PROBLEM WITH
COMBUSTION AIRFLOW. PURGE LIGHT BLINKS.
SAFETY SEQUENCES DURING OPERATION
DRAFT INDUCER TEMPERATURE SAFETY SWITCH
D E
DRAFT INDUCER RUNS THRU 30 SECOND
POST PURGE AND SWITCHES OFF.
CIRCULATOR RUNS WITH THERMOSTAT ON
CALL FOR HEAT.
WHEN TEMPERATURE SAFETY SWITCH
CONTACTS REMAKE BEFORE END OF CALL
FOR HEAT, CONTROL GOES INTO NORMAL
LIGHT-OFF SEQUENCE.
LOSS OF FLAME SIGNAL
DRAFT INDUCER RUNS THRU 30 SECOND
POST PURGE
LOSS OF COMBUSTION AIRFLOW
DRAFT INDUCER RUNS THRU 30 SECOND
POST PURGE
IF CALL FOR HEAT REMAINS, IBC WAITS 15 MINUTES
FOR AIRFLOW TO BE RE-ESTABLISHED
CASTING TEMPERATURE SAFETY SWITCH
IF BURNER OPERATES WHEN BOILER HAS NO
WATER, ALUMINUM BOILER SECTIONS HEAT
UP RAPIDLY.
HI LIMIT CONTROL
DRAFT INDUCER CONTINUES TO RUN FOR 30
SECOND POST PURGE AND SWICHOFF.
CIRCULATOR RUNS AS LONG AS THERMOSTAT
CALL FOR HEAT.
WHEN HI LIMIT CONTACTS REMAKE BEFORE
END OF CALL FOR HEAT - CONTROL INTO A
NORMAL LIGHT OF SEQUENCE
CIRCULATOR PUMP
CIRCULATOR WILL BE ENERGIZED AS LONG AS
THERMOSTAT CALLS FOR HEAT DURING LOCKOUT
RECOVERY FROM ANY LOCKOUT REQUIRES RESET
WHICH IS ACCOMPLISHED BY REMOVING AND
REAPPLYING THE THERMOSTAT CALL FOR HEAT OR
POWER TO CONTROL
DETAILED SEQUENCE OF OPERATION
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