Vanguard Heating VMH26TPC - Manual (Page 24)

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POSSIBLE CAUSE
1. Control knob not fully pressed
in
2. Control knob not pressed in
long enough
3. Safety interlock system has
been triggered
4. Equipment shutoff valve not
fully open
5. Thermocouple connection
loose at control valve
6. Pilot flame not touching ther-
mocouple, which allows ther-
mocouple to cool, causing
pilot flame to go out. This
problem could be caused by
one or both of the following:
A) Low gas pressure
B) Dirty or partially clogged
ODS/pilot
7. Thermocouple damaged
8. Control valve damaged
1. Burner orifice is clogged
2. Inlet gas pressure is too low
1. Manifold pressure is too low
2. Burner orifice is clogged
1. Burner orifice is clogged or
damaged
2. Burner damaged
3. Low inlet gas pressure
4. Gas regulator defective
1. Not enough air
2. Gas regulator defective
REMEDY
1. Press in control knob fully
2. After ODS/pilot lights, keep
control knob pressed in 30
seconds
3. Wait one minute for safety in-
terlock system to reset. Repeat
ignition operation
4. Fully open equipment shutoff
valve
5. Hand tighten until snug, then
tighten 1/4 turn more
6. A) Contact local propane/LP
or natural gas company
B) Clean ODS/pilot (see
Cleaning and Maintenance,
page 22) or replace ODS/pilot
assembly
7. Replace pilot assembly
8. Replace control valve
1. Clean burner (see Cleaning
and Maintenance, page 22)
or replace burner orifice
2. Contact local propane/LP or
natural gas company
1. Contact local propane/LP or
natural gas company
2. Clean burner (see Cleaning
and Maintenance, page 22)
or replace burner orifice
1. Clean burner (see Cleaning
and Maintenance, page 22)
or replace burner orifice
2. Replace burner pressure
3. Contact local propane/LP or
natural gas company
4. Replace gas regulator
1. Check burner for dirt and
debris. If found, clean burner
(see Cleaning and Mainte-
nance, page 22)
2. Replace gas regulator
OBSERVED PROBLEM
ODS/pilot lights but flame
goes out when control knob is
released
Burner does not light after
ODS/pilot is lit
Delayed ignition of burner
Burner backfiring during com-
bustion
Yellow flame during burner
combustion
TROUBLESHOOTING
Continued