UTICA BOILERS UB90-200 Installation, Operation & Maintenance Manual page 40

Troubleshooting Chart 6
CHART 5
YES
SET THERMOSTAT BELOW ROOM
TEMPERATURE TO END CALL FOR
HEAT
YES
DOES CIRCULATOR PUMP STOP?
YES
VALE LIGHT IS OFF
YES
DOES DRAFT BLOWER
STOP AFTER 30
SECOND POST PURGE?
YES
SYSTEM OK
TROUBLESHOOTING
CHART 5
NO #3
IS UNIT FIRING AT THE CORRECT RATE?
CHECK BURNER FOR ANY DETERIORATION
IN THE FLAME PORTS. ARE BURNER PORTS
SPECIFIC INSTRUCTIONS. REQUIRES
BOILER SHUTS OFF BEFORE END OF
CALL FOR HEAT. ARE HI LIMIT
AQUASTAT CONTACTS CLOSED?
YES
SEE TROUBLESHOOTING PATH
#2 ABOVE
NO
ARE THERMOSTAT CONTACTS OPEN?
REPLACE IBC
REMOVE WIRING HARNESS
NO
CONNECTION CN9 FROM GAS
CONTROL DOES GAS CONTROL
CLOSE?
NO
REPLACE IBC
CHART 5
NO #2
RUNS FOR 25-50 SECONDS,
THEN TURNS OFF.
CHECK FIRING RATE OF UNIT.
YES
IN GOOD CONDITION.
YES
CHECK FLAME SIGNAL > 0.6uA?
CONSULT BOILER MFGR. FOR
SPECIFIC TOOLS.
BOILER OFF ON HIGH LIMIT. IS
NO
ACTUAL BOILER WATER TEMP.
GREATER THAN HI LIMIT SET POINT
MINUS 30°F CONTROL DIFFERENTIAL?
NO
YES
NO
YES
40
REPLACE GAS CONTROL.
YES
CHECK GAS ORFICICE SIZE.
IS GAS ORIFICE SIZE CORRECT.
CHECK REPAIR PARTS LIST
FOR CORRECT SIZE. IS GAS ORIFICE
CLEAR OF BLOCKAGE.
YES
NO
DOES THE UNIT USE LP GAS.
NO
ADJUST RATE AS DESCRIBED IN THE
CHECK OUT PROCEDURE AND
ADJUSTMENT SECTION
OF THE MANUAL.
NO
REPLACE WITH CORRECT
AIR BAFFLE.
NO
REPLACE BURNER
YES
REPLACE IBC
NO
AQUASTAT
NO
REPLACE THERMOSTAT
REPLACE GAS CONTROL
REPLACE
OK