Monessen Hearth NB18 Installation Instructions Manual page 44

NB18/NB24 Gas Log Set
If the gas quality is bad, your pilot may not stay lit, the
burners may produce soot and the heater may backfi re
when lit. If the gas quality or pressure is low, contact your
local gas supplier immediately.
Problem
ODS/pilot lights, but fl ame goes out
when control knob is released.
Burner does not light after ODS/pilot
is lit.
Burner backfi res during combustion.
Slight smoke or odor combustion.
Logs appear to smoke after initial
operation.
Heater produces a whistling noise
when burner is lit.
No gas to pilot.
44
Possible Cause
1. Control knob not fully pressed in.
2. Control knob not pressed in long
enough.
3. Manual shutoff valve not fully open.
4. Thermocouple connection loose at
control valve.
5. Pilot fl ame not touching thermocouple,
which allows thermocouple to cool,
causing pilot fl ame to go out. This
problem could be caused by either
low gas pressure, or a dirty or partially
clogged ODS/pilot.
6. Thermocouple damaged.
7. Control valve damaged.
1. Burner orifi ce is clogged.
2. Burner orifi ce diameter is too small.
3. Inlet gas pressure is too low.
1. Manifold pressure is too low.
2. Burner orifi ce is clogged.
1. Burner orifi ce is clogged or damaged.
2. Burner is damaged.
3. Gas regulator defective.
1. Vapor from paint or curing process of
logs.
1. Turning control knob to HIGH position
when burner is cold.
2. Air in gas line.
3. Dirty or partially clogged burner
orifi ces.
1. LP-regulator shut down due to inlet
pressure too high.
TROUBLESHOOTING
Solution
1. Press control knob in fully.
2. After ODS/pilot lights, keep control
knob pressed in for 30 seconds.
3. Fully open manual shutoff valve.
4. Hand tighten thermocouple
connection until snug, then tighten 1/4
turn more.
5. Contract local gas company.
6. Replace thermocouple.
7. Replace control valve.
1. Burner orifi ce is clogged.
2. Burner orifi ce diameter is too small.
3. Inlet gas pressure is too low.
1. Contact local gas company.
2. Clean burner or replace burner orifi ce.
1. Clean burner or replace burner orifi ce.
2. Replace burner.
3. Replace gas regulator.
1. Problem will stop after a few hours
of operation. Run the heater with the
damper open if you have one, or open
a window for the fi rst few hours.
2. Log heater is intended to be
smokeless. Turn OFF heater and call
qualifi ed service person.
1. Turn control knob to LOW position
and let warm up for a minute.
2. Operate burner until air is removed
from line. Have gas line checked by
local gas company.
3. Clean burner or replace burner orifi ce.
1. Verify LP tank regulator is installed
and set at 11" to 13" w.c.
2. Replace regulator on heater.
81D0107