Heatilator • Novus NBV • 4055-188 Rev C • 04/08 35

With proper installation, operation and maintenance your gas appliance will provide years of trouble-free service. If you do

experience a problem, this troubleshooting guide will assist a qualifi ed service person in the diagnosis of a problem and the

corrective action to be taken. This troubleshooting guide can only be used by a qualifi ed service technician.

A. Standing Pilot Ignition System

Symptom Possible Causes Corrective Actions

1. After repeated triggering
of the red or black piezo
ignitor button, the spark
ignitor will not light the
pilot.
A. Defective ignitor. Check the spark at the electrode and pilot. If there is no spark and the
electrode wire is properly connected, replace the ignitor.
B. Defective pilot or
misaligned electrode
(spark at electrode).
Using a match, light the pilot. If the pilot lights, turn off the pilot and trigger
the red or black piezo ignitor button again. If the pilot lights, an improper
gas/air mixture caused the bad lighting and a longer purge period is
recommended. If the pilot will not light, ensure the gap at the electrode and
pilot is 1/8 in. to have a strong spark. If the gap is OK, replace the pilot.
C. No gas or low gas
pressure.
Check the remote shut-off valves from the appliance. There is usually a
valve near the gas main. There can be more than one valve between the
appliance and the main.
D. No LP in tank. Check the LP (propane) tank. You may be out of fuel.
2. The pilot will not stay lit
after carefully following
the lighting instructions
A. Defective thermocouple. Check that the pilot fl ame impinges on the thermocouple. Clean and/or
adjust the pilot for maximum fl ame impingement.
Ensure that the thermocouple connection at the gas valve is fully inserted
and tight (hand tighten plus 1/4 turn).
Disconnect the thermocouple from the valve, place one millivolt meter lead
wire on the tip of the thermocouple and the other meter lead wire on the
thermocouple copper lead. Start the pilot and hold the valve knob in. If the
millivolt reading is less than 15mV, replace the thermocouple.
B. Defective valve. If the thermocouple is producing more than 15 millivolts, replace faulty valve.
3. The pilot is burning, there
is no gas burning, the
valve knob is in the ON
position, and the ON/
OFF switch is in the ON
position.
A. ON/OFF switch or wires
are defective.
Check the ON/OFF switch and wires for proper connections. Place the
jumper wires across the terminals at the switch. If the burner comes on,
replace the defective switch. If the switch is OK, place the jumper wires
across the switch wires at the gas valve. If the burner comes on, the wires
are faulty or connections are bad.
B. Thermopile may not be
generating suffi cient
millivoltage.
If the pilot fl ame is not close enough physically to the thermopile, adjust the
pilot fl ame.
Be sure the wire connections from the thermopile at the gas valve terminals
are tight and that the thermopile is fully inserted into the pilot bracket.
Check the thermopile with a millivolt meter. Take the reading at TH-TP&TP
terminals of the gas valve. The meter should read 325 millivolts minimum
while holding the valve knob depressed in the pilot position, with the pilot lit,
and the ON/OFF switch in the OFF position. Replace the faulty thermopile of
the reading is below the specifi ed minimum.
With the pilot in the ON position, disconnect the thermopile leads from
the valve. Take a reading at the thermopile leads. The reading should be
325 millivolts minimum. Replace the thermopile if the reading is below the
minimum.
C. Defective valve. Turn the valve knob to the ON position. Place the ON/OFF switch in the ON
position. Check the millivolt meter at the thermopile terminals. The millivolt
meter should read greater than 125mV. If the reading is acceptable, and if
the burner does not come on, replace the gas valve.
D. Plugged burner orifi ce. Check the burner orifi ce for stoppage. Remove stoppage.
E. Wall switch or wires are
defective.
Follow the corrective action in Symptom and Possible Cause 1.A. above.
Check the switch and wiring. Replace where defective.
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14 Troubleshooting