Vanguard Heating VN18A - Manual (Page 21)

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TROUBLESHOOTING
Continued
POSSIBLE CAUSE
1. Control knob not fully pressed in
2. Control knob not pressed in
long enough
3. Equipment shutoff valve not
fully open
4. Thermocouple connection
loose at control valve
5. Pilot flame not touching ther-
mocouple, which allows ther-
mocouple to cool, causing pi-
lot flame to go out. This prob-
lem could be caused by one or
both of the following:
A) Low gas pressure
B) Dirty or partially clogged
ODS/pilot
6. Thermocouple damaged
7. Control valve damaged
8. Safety interlock system has
been triggered (thermostat
models only)
1. Burner orifice(s) is clogged
2. 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
1. Plaque damaged
2. Inlet gas pressure is too low
3. Control knob set between
locked positions
1. Residues from manufacturing
processes
REMEDY
1. Press in control knob fully
2. After ODS/pilot lights, keep con-
trol knob pressed in 30 seconds
3. Fully open equipment shutoff
valve
4. Hand tighten until snug, then
tighten 1/4 turn more
5. A) Contact local natural or
propane/LP gas company
B) Clean ODS/pilot (see
Cleaning and Maintenance,
page 19) or replace ODS/pi-
lot assembly
6. Replace pilot assembly
7. Replace control valve
8. Wait one minute for safety in-
terlock system to reset. Repeat
ignition operation
1. Clean burner orifice(s) (see
Cleaning and Maintenance,
page 19) or replace burner
orifice(s)
2. Contact local natural or pro-
pane/LP gas company
1. Contact local natural or pro-
pane/LP gas company
2. Clean burner orifice(s) (see
Cleaning and Maintenance,
page 19) or replace burner
orifice(s)
1. Clean burner orifice(s) (see
Cleaning and Maintenance,
page 19) or replace burner
orifice(s)
2. Replace burner
3. Replace gas regulator
1. Replace burner
2. Contact local natural or pro-
pane/LP gas company
3. Turn control knob until it
locks at desired setting
1. Problem will stop after a few
hours of operation
OBSERVED PROBLEM
ODS/pilot lights but flame goes
out when control knob is re-
leased
Burner(s) does not light after
ODS/pilot is lit
Delayed ignition of burner(s)
Burner backfiring during com-
bustion
Burner plaque(s) does not glow
Slight smoke or odor during ini-
tial operation