Bryant BW9 - Normal Sequence of Operation; Detailed Sequence of Operation

Fig. 24—Normal Sequence of Operation
A00314
2 SEC INTO THE 5 SEC IGNITION TRIAL, POWER
IS TURNED OFF TO THE HOT SURFACE IGNITER.
IGNITER LIGHT OFF.
GAS VALVE OPENS FOR 5 SEC TRIAL FOR
IGNITION, BLUE ORANGE GLOW OF THE BURNER
CAN BE SEEN THRU OBSERVATION PORT.
GAS VALVE ENERGIZED THRU 3K1 AND 4K1.
CONTACTS. VALVE LIGHT ON.
PURGE LIGHT GOES OUT. HOT SURFACE IGNITER
POWERED THRU 5K1 AND 5K2 CONTACTS FOR 20
SEC IGNITER WARMUP. BRIGHT YELLOW
ORANGE GLOW OF THE HOT SURFACE IGNITER
CAN BE OBSERVED THRU THE OBSERVATION
PORT IN FRONT OF BOILER SECTION JUST
ABOVE IGNITER. iGNITOR LIGHT ON.
DURING THE LAST 2 SEC OF THE 5 SEC IGNITION
TRIAL. MAIN BURNER FLAME IS PROVED BY FLAME
RECTIFICATION THRU THE HOT SURFACE IGNITER,
PROVIDING A FLAME SIGNAL TO IBC. GAS VALVE
REMAINS ENERGIZED. BOILER RUNS.
DETAILED SEQUENCE OF OPERATION
PURGE LIGHT ON. AIRFLOW PROVED.
DRAFT INDUCER RUNS FOR 15 SEC PREPURGE.
CONTROL LOCKOUT. PURGE LIGHT BLINKS.
RESET REQUIRED.
CIRCULATOR REMAINS ENERGIZED
AS LONG AS THERMOSTAT CONTINUES
TO CALL FOR HEAT.
OPEN
IBC
WAITS FOR
UP TO 5 MINUTES
FOR AIR PRESSURE
SWITCH CONTACTS
TO CLOSE
INDICATING FAN
SUCTION PRESENT
C
LOSED
DRAFT INDUCER
ENERGIZES THRU
1K1 CONTACTS
CLOSED
OPEN
OPEN
CLOSED
YES
NO
DOES MAIN
BURNER PROVE
FLAME WITHIN
INITIAL TRIAL FOR
IGNITION PERIOD
NORMAL
OPERATION
CONTROL WILL ATTEMPT 2 ADDITIONAL
IGNITION SEQUENCES. STARTING WITH
PREPURGE.
IF MAIN BURNER DOES NOT PROVE FLAME
IN 3 TRIALS, CONTROL LOCKOUT. VALVE/
FLAME LIGHT BLINKS. RESET IS REQUIRED.
THIS PROBLEM IS A RESULT OF NOT
ESTABLISHING FLAME SIGNAL.
FALSE POSITIVE
PROOF OF
AIRFLOW. IBC
WAITS FOR 45 SEC
FOR AIR
PRESSURE
SWITCH CONTACTS
TO OPEN
IBC
CHECKS
N.O. AIR
PRESSURE
SWITCH
CONTACTS
IBC SELF CHECK OF
INTERNAL CIRCUITRY
1-2 SEC
CIRCULATOR
ENERGIZES THRU
2K1 CONTACTS
THERMOSTAT
CALLS FOR HEAT
POWER ON
STANDBY
NORMAL SEQUENCE OF OPERATION
—32—