26
TROUBLESHOOTING
Figure 8.2: Boiler Troubleshooting Guide (Burners Not Functioning)
SYSTEM IS OKAY
CHECK FOR PROPER VOLTAGE
AT CONTROL HARNESS (SEE INSET
A). VOLTAGE SHOULD BE 24V
BETWEEN THERMOSTAT AND
24V COMMON, AND 24V BETWEEN
24V COMMON AND 24V HOT.
PLUG HARNESS INTO GAS VALVE
CONTROL. WAIT FOR INTERNAL
CHECK DELAY
UNPLUG PILOT BURNER CABLE.
MEASURE VOLTAGE AT GAS VALVE
HSI ELEMENT OUTPUT (SEE INSET B)
24V NOMINAL
RECONNECT PILOT BURNER CABLE
CYCLE THERMOSTAT OFF AND BACK ON
IF MAIN BURNERS DO NOT LIGHT,
REPLACE GAS VALVE
REPLACE GAS VA LVE
REPLACE GAS VA LVE
INSET B
INSET A
END VIEW OF
CONTROL
HARNESS
CONNECTOR
24 VOLT
THERMOSTAT
24
VOLTS
24
VOLTS
24 VOLT
HOT
CHECK FOR DAMAGED OR MISSING
TERMINALS IN CONNECTOR
24 VOLT
COMMON
HSI
TERMINAL
NO
NO
NO
NO NO
YES
YES
YES
YES
YES
YES
YES
CHECK TRANSFORMER AND
LINE VOLT SUPPLY
RECONNECT PILOT BURNER
CABLE
REPLACEIGNITER/FLAME RODASSEMBLY
REPLACEIGNITER/FLAME RODASSEMBLY
IGNITER WARMS UP AND
GLOWS RED
NOTE: IGNITER WILL CYCLE OFF
AND BACK ON ONCE DURING THE
90 SECOND IGNITION TRIAL
MAIN VALVE OPENS AND
MAIN BURNER LIGHTS
●
●
●
●
TURN OFF GAS SUPPLY
ASSURE GAS VALVE SWITCH IS
IN "ON" POSITION
DISCONNECT SYSTEM CONTROL
HARNESS
SET THERMOSTAT TO CA LL
FOR HEAT
●
●
●
CHECK:
LINE VOLTAGE POWER
LOW VOLTAGE TRANSFORMER
LIMIT CONTROLLER
THERMOSTAT
WIRING
●
●
●
●
●
CHECK THAT PILOT GAS IS FLOWING.
WAIT TO ASSURE PILOT GAS TUBING
IS PURGED.
●
●
●
MEASURE VOLTAGE BETWEEN 24V
HOT AND 24V COMMON LEADS TO GAS
VALVE. MUST MEASURE AT LEAST
19.5 VAC WITH IGNITER POWERED.
SEE INSET A TO IDENTIFY PROPER
LEAD.THIS CHECK MUST BE DONE
WITH THE GAS VALVE CONNECTED
AND IGNITER POWERED.
●
●
●
●
●
●
●
●
●
●
TURN ON GAS SUPPLY
PILOT BURNER LIGHTS
CHECK THAT PILOT FLAME MAKES
GOOD CONTACT WITH PILOT BURNER
FLAME ROD.
CHECK FOR GOOD ELECTRICAL
CONNECTION THROUGH THE PILOT
TUBING
IF BOTH OF THE ABOVE ARE GOOD,
REPLACE IGNITER/FLAME ROD
ASSEMBLY.
●
●
●
●
●
●
●
●
●
NO
NO
1) CHECK FOR 24VAC AT PRESSURE
SWITCH "NO" TERMINAL TO GROUND.
IF NO VOLTAGE, CHECK FOR:
- BLOCKED OR CRACKED SUCTION
TUBING.
- FAN NOT GENERATING ADEQUATE
SUCTION PRESSURE.
- DEFECTIVE PRESSURE SWITCH.
2) CHECK FOR 24VAC AT ISOLATION RELAY
BLUE WIRES TO GROUND:
- IF NO VOLTAGE AT EITHER BL WIRES,
CHECK FOR BROKEN/LOOSE WIRE.
- IF NO VOLTAGE AT ONLY ONE BL WIRE,
CHECK FOR 120VAC BETWEEN RELAY
BLACK AND WHITE WIRES. IF SO,
REPLACE RELAY.
3) CHECK FOR 24VAC AT FLAME ROLL-OUT
SWITCH. IF SWITCH IS BLOWN, CORRECT
CAUSE OF ROLL-OUT BEFORE
REPLACING SWITCH.
x
1)x
1)x
1)x
1)x-
1)x
1)x-
1)x
x
2)x
2)x
2)x-
2)x
2)x-
2)x-
2)x-
x
3)x
3)x
3)x
CHECK FOR 24VAC AT PRESSURE SWITCH
TERMINALS "C" AND "NC" TO GROUND:
IF VOLTAGE AT "NC" BUT NOT "C",
PRESSURE SWITCH IS STUCK IN
RUNNING POSITION. CHECK FOR BLOCKED
AIR TUBE. IF OKAY, REPLACE PRESSURE
SWITCH.
IF NO VOLTAGE AT EITHER PRESSURE
SWITCH TERMINAL "C" OR "NC" TO
GROUND, CHECK FOR 120VAC INCOMING
POWER INSIDE JUNCTION BOX. IF PROPER
INCOMING POWER, REPLACE
TRANSFORMER/RELAY.
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●
●
●
●
●
●
●
●
●
●
●
CHECKFOR120VAC HIGH LIMIT CONTROL.IF
POWERAT ONETERMINAL BUT NOTBOTH,
REPLACELIMIT CONTROL.
JUMPER THERMOSTAT
AT CONNECTIONS
"G" AND "Y" ON
TRANSFORMER.
DOES BOILER RUN?
CORRECT
THERMOSTAT
PROBLEM
NO
SEE TABLE 8.1
DOES IGNITER WARM
UP AND GLOW RED?
(INTERMITTENTLY)
IS FAN RUNNING?
DO BURNERS
FUNCTION?
YES
YES
YES
NO
YES
NO
NO
NO
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