Starting The Unit; Sequence Of Operations - Thermo Pride CMA3-50D36N Installation And Service Manual

V. STARTING THE UNIT
A. SEQUENCE OF OPERATIONS
AT ANY TIME THE
GAS VALVE IS
NOT ENERGIZED
START
PRESSURE SWITCH SENSES
ADEQUATE DIFFERENTIAL PRESSURE,
START
TRIAL
FOR
IGNITION
CONTINUOUS SAFE OPERATION CHECK
PRESENT OR ROLL-OUT SWITCH OPENS, SYSTEM
ENERGIZES INDUCER FAN FOR 15 SECONDS AND CIRCULATOR BLOWER AT
HEATING SPEED UNTIL SITUATION CORRECTION
THERMOSTAT CALLS FOR
HEAT, CONTACTS CLOSE
CONTROL BOARD ENERGIZED,
INDUCER ENERGIZED
CONTACTS CLOSE
POWER IS APPLIED TO
THE SILICON NITRIDE
IGNITOR. IGNITOR
WARM-UP IS 20 SECONDS.
AFTER IGNITOR WARM-UP,
THE GAS VALVE IS
ENERGIZED TO OPEN
FLAME MUST BE DETECTED
WITHIN 4 SECONDS IF
FLAME IS DETECTED, THE
DELAY-TO-FAN-ON TIME
BEGINS (45 SECONDS)
IF FLAME SIMULATION CONDITION
41
POWER INTERRUPTION
SYSTEM SHUTS OFF,
RESTARTS WHEN POWER
IS RESTORED.
IF FLAME IS NOT DETECTED, THE
GAS VALVE IS DE-ENERGIZED,
THE IGNITOR IS TURNED OFF AND
THE CONTROL BOARD CONTROL GOES
INTO "RETRY" SEQUENCE.