UL# MH19366
Rev. A2003
14
MAINTENANCE & CLEANING CONT’D
Testing Safeties and Controls
The pilot combination valve can only be checked with a multi-meter that measures
mili-volts.
Connect the mulit-meter to the top terminal of the combination valve marked
“TH/TP” and the body of the combination valve. The voltage should read 400 to
500 MV with the burner off.
Between “TH” and “TP” the voltage should read above 150 MV with the burner on.
If no voltage is present at the combination valve, install a thermocouple tester
between the thermocouple and the combination valve, and then retake the voltage
measurements.
If no voltage is present, replace the thermocouple.
If voltage is present, replace the combination valve.
Trouble Shooting
If an item on the list is followed by an asterisk (*), the work should be
done by a factory authorized service representative.
Symptom Problem Solution
Incosistant Heat
Incorrect Gas pressure.
Verify gas pressure and adjust accordingly. *
Plugged vent on regulator
Remove vent and clean.
Faulty
regulator Replace
regulator.
Defective temperature sensing probe
Verify that temperature sensing probe has the
right resistance for temp (contact Lang MFG.). *
Defective Controller
Contact NCC Controls.
Pilot will not stay lit
Plugged pilot orifice
Clean orifice.
Plugged vent on regulator
Remove vent and clean.
Defective thermocouple
Replace thermocouple. *
Defective valve
Replaced valve. *
Main burner will not ignite Incorrect gas pressure.
Verify gas pressure and adjust accordingly. *
Plugged vent on regulator
Remove vent and clean.
Faulty
regulator Replace
regulator.
Plugged burner orifice
Clean burner orifice.
Dirty or defective thermocouple
Clean or replace thermocouple. *
Defective valve
Replace valve. *
Defective temperature sensing probe
Verify that temperature sensing probe has the
right resistance for temp (contact Lang MFG.). *
Defective Controller
Contact NCC Controls.
