32
MB Pool & spa heater
055, 105 & 155 Models
ELECTRICAL TROUBLESHOOTING
START
SET THERMOSTAT
TO CALL FOR HEAT
DOES THE
DIAGNOSTIC
LED STAY ON?
YES
AFTER PREPURGE
IS THERE SPARK
AT THE PILOT
ASSEMBLY?
YES
PILOT BURNER
LIGHTS
YES
SPARK STOPS WHEN
PILOT IS LIT
YES
MAIN BURNER LIGHTS?
YES
SYSTEM RUNS UNTIL
CALL FOR HEAT ENDS
YES
CALL FOR HEAT OVER
SYSTEM SHUTS OFF
YES
END TROUBLESHOOTING
NO
NO
NO
NO
NO
CHECK LINE VOLTAGE POWER.
CONFIRM TRANSFORMER OUTPUT,
LIMIT CONTROLLERS, THERMOSTAT
AND WIRING. ALSO, INDUCED
DRAFT FAN AND AIR PROVING
SWITCH ON INDUCED DRAFT
SYSTEMS.
CHECK IGNITION CABLE, GROUND
WIRING, PILOT ASSEMBLY
INSULATOR AND GAP. CHECK
CABLE FOR SIGNS OF MELTING.
CHECK VALVE, VALVE WIRING, GAS
SHUT OFF VALVES.
CHECK FLAME SENSE WIRE AND GROUND
WIRE. CHECK PILOT FLAME COVERS SENSE
ROD. CLEAN SENSE ROD.
CHECK VALVE, VALVE WIRING.
CHECK LIMITS AND CIRCULATION FAN. CHECK
CONTINUITY OF SENSOR CABLE AND GROUND
WIRE. POOR GROUNDING MAY CAUSE
OCCASIONAL SHUTDOWNS. CHECK FOR EXCESSIVE
HEAT AT FLAME SENSOR INSULATOR.
CHECK THERMOSTAT
CHECK VALVE
CHECK FOR 25VAC
NOMINAL AT TH & TR
TERMINALS
YES
REPLACE CONTROL
IS THERE ANY
AUDIBLE SPARK
NOISE @ 5 SPARKS/
SEC?
NO
REPLACE CONTROL
NO
NO
NO
YES
WARNING
HIGH VOLTAGE
For qualifi ed Technicians ONLY
*
NOTE: This heater is equipped with an
ignition module that shuts off pilot gas if pilot
fails to light after the third attempt. This is
identifi ed by the LED fl ashing on the ignition
module. To reset, interrupt power to heater.
*