Vanguard VN12A Owner's Operation And Installation Manual page 22

TROUBLE-
SHOOTING
Continued
22
OBSERVED
PROBLEM
ODS/pilot lights but
flame goes out when
control knob is
released
Burner(s) does not
light after ODS/pilot
is lit
Delayed ignition of
burner(s)
Burner backfiring
during combustion
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 connec-
tion loose at control
valve
5. Pilot flame not touch-
ing thermocouple,
which allows thermo-
couple 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
6. Thermocouple dam-
aged
7. Control valve damaged
1. Burner orifice(s) is
clogged
2. Burner orifice(s)
diameter is too small
3. Inlet gas pressure is
too low
1. Manifold pressure is
too low
2. Burner orifice(s) is
clogged
1. Burner orifice(s) is
clogged or damaged
2. Burner damaged
3. Gas regulator defective
REMEDY
1. Press in control knob
fully
2. After ODS/pilot lights,
keep control knob
pressed in 10 seconds
3. Fully open manual
shut-off valve
4. Hand tighten until
snug, then tighten 1/4
turn more
5. A) Contact local
natural gas company
B) Clean ODS/pilot
(see Cleaning and
Maintenance, page 20)
or replace ODS/pilot
assembly
6. Replace thermocouple
7. Replace control valve
1. Clean burner orifice(s)
(see Cleaning and
Maintenance, page 20)
or replace burner
orifice(s)
2. Replace burner
orifice(s)
3. Contact local natural
gas company
1. Contact local natural
gas company
2. Clean burner orifice(s)
(see Cleaning and
Maintenance, page 20)
or replace burner
orifice(s)
1. Clean burner orifice(s)
(see Cleaning and
Maintenance, page 20)
or replace burner
orifice(s)
2. Replace burner
3. Replace gas regulator
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