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30
NO
NO
NO
HOSE SECURELY
CONNECTED TO
CANOPY?
YES
YES
VENT SYSTEM
FREE OF
OBSTRUCTIONS?
YES
REPLACE
BLOWER
CLEAR
OBSTRUCTIONS
NO
REPLACE HOSE
CONNECT HOSE
TO CANOPY
NO
HOSE FREE OF
CRACKS OR
HOLES?
CONNECT MANOMETER TO
SUCTION PRESSURE SWITCH
(SEE Figure 24). IS SUCTION
PRESSURE GREATER THAN:
-0.50 IWC FOR PIN3/4PV
-0.80 IWC FOR PIN5/6PV
YES
REPLACE SUCTION PRESSURE
SWITCH
REPLACE IGNITION MODULE
NO
NO
24 VOLTS AT SUCTION
PRESSURE SWITCH
TERMINAL 'NO'?
YES
DISCONNECT IGNITER/SENSOR
CABLE FROM IGNITION MODULE
TERMINAL (9). HOLD CABLE
NEAR TERMINAL. IS SPARK
PRESENT?
YES
CHECK IGNITER/SENSOR CABLE, GROUND WIRE, CERAMIC
INSULATOR, AND GAP. CHECK IGNITER/SENSOR CABLE BOOT FOR
SIGNS OF MELTING OR BUCKLING.
GO TO PAGE 31
NO
DOES BLOWER ENERGIZE?
YES
SPARK PRESENT
AT PILOT IGNITER/
SENSOR?
YES
TURN OFF GAS SUPPLY.
ADJUST THERMOSTAT TO CALL FOR HEAT.
DID BLOWER OPERATE
FOR 30 TO 50 SECONDS
BEFORE SPARK BEGAN?
NO
REPLACE IGNITION
MODULE
YES
TURN ON GAS SUPPLY.
DOES PILOT BURNER
LIGHT?
YES
24 VOLTS ACROSS GAS
VALVE TERMINALS 'PV'
AND 'MV-PV'?
YES
NO
NO
YES
NO
OPEN VALVES
ALL MANUAL GAS VALVES OPEN?
IS PILOT BURNER ORIFICE
BLOCKED?
YES
CLEAN OR REPLACE PILOT
BURNER ORIFICE
NO
NO
24 VOLTS ACROSS IGNITION
MODULE TERMINALS 'PV' AND
'MV-PV'?
REPLACE IGNITION
MODULE
YES
CONTACT GAS
SUPPLIER
NO
IS GAS SUPPLY PRESSURE
BETWEEN 4.5 AND 13.5 IWC?
YES
REPAIR OR REPLACE WIRES
REPLACE GAS VALVE
CHECK CONTINUITY OF IGNITION CABLE AND GROUND WIRE. CLEAN FLAME ROD.
CHECK ELECTRICAL CONNECTIONS BETWEEN FLAME ROD AND IGNITION MODULE.
CHECK FOR CRACKED CERAMIC FLAME ROD INSULATOR. CHECK PILOT FLAME (SEE
Figure 19). IF CHECKS OKAY, REPLACE IGNITION MODULE.
NO
DOES SPARK STOP
AFTER PILOT IS LIT?
YES
MAIN BURNER LIGHTS?
YES
BOILER CONTROL SYSTEM
SEQUENCING PROPERLY.
CHECK DISTRIBUTION
SYSTEM
24 VOLTS ACROSS GAS
VALVE TERMINALS 'MV'
AND 'MV-PV'?
YES
REPLACE GAS VALVE
NO
24 VOLTS ACROSS IGNITION
MODULE TERMINALS 'MV' AND
'MV-PV'?
YES
REPAIR OR REPLACE WIRES
NO
REPLACE IGNITION
MODULE
NO