Troubleshooting; Millivolt Control System - Monessen Hearth NB18 Installation And Operating Instructions Manual

NB18/NB24 Gas Log Set
Turn appliance OFF and allow to cool before
servicing. Only a qualified service person
should service and repair the heater.
NOTE: All troubleshooting items are listed in order of operation.
Problem
When ignitor button is pressed, there is
no spark at ODS/pilot.
Appliance produces unwanted odors.
Appliance shuts off during use.
Gas odor even when control knob is in
OFF position.
When ignitor button is pressed, there is
spark at ODS pilot, but no ignition.
40
Possible Cause
1. Ignitor electrode positioned wrong.
2. Ignitor electrode is broken.
3. Ignitor electrode not connected to
ignitor cable.
4. Ignitor cable pinched or wet. Keep
ignitor cable dry.
5. Broken ignitor cable.
6. Bad piezo ignitor.
1. Appliance burning vapors from paint,
hair spray, glues, etc.
2. Gas leak.
3. Initial burn off.
1. Not enough fresh air is available for
ODS/pilot to operate.
2. Low line pressure.
3. ODS/pilot is partially clogged.
4. Defective thermopile.
5. Restrictions in incoming air flow.
1. Gas leak.
2. Control valve defective.
1. Gas supply turned off or manual
shutoff valve closed.
2. Control knob not in PILOT position.
3. Control knob not pressed in while in
PILOT position.
4. Air in gas lines when installed.
5. ODS/pilot is clogged.
6. Gas regulator setting is not correct.

TROUBLESHOOTING

Solution
1. Replace ignitor.
2. Replace ignitor.
3. Reconnect ignitor cable.
4. Free ignitor cable if pinched by any
metal or tubing.
5. Replace ignitor cable.
6. Replace piezo ignitor.
1. Ventilate room. Stop using odor
causing products while heater is
running.
2. Locate and correct all leaks.
3. Ventilate room and turn unit on high
until odor is gone. Odor should be
gone after six hours of continuous
use.
1. Open window and/or door for
ventilation.
2. Contact local gas company.
3. Clean ODS/pilot.
4. Check wire connections. Check
output should be 500 millivolts across
TH/TP and TP Terminals with ON/
OFF switches off.
5. Check for bottom riser on glass door,
sunken fireplace, excessive lava rock/
cinders densely packed against grate.
1. Locate and correct all leaks.
2. Replace control valve.
1. Turn on gas supply or open manual
shutoff valve.
2. Turn control knot to PILOT position.
3. Press in control knob while in PILOT
position.
4. Continue holding down control knob.
Repeat igniting operation until air is
removed.
5. Replace ODS/pilot assembly or get it
serviced.
6. Check incoming pressure. Replace
gas regulator.
81D0107