Troubleshooting - Vanguard VMH3000TNA Owner's Operation And Installation Manual

NATURAL GAS RESIDENTIAL HEATERS

TROUBLESHOOTING

Note: For additional help, visit DESA
International's technical service web site
at www.desatech.com.
Note: All troubleshooting items are listed in
order of operation.
OBSERVED PROBLEM
When ignitor button is pressed, there is no
spark at ODS/pilot
When ignitor button is pressed, there is
spark at ODS/pilot but no ignition
ODS/pilot lights but flame goes out when
control knob is released
For more information, visit www.desatech.com
®
WARNING: Turn off and un-
plug heater and let cool before
servicing. Only a qualified ser-
vice person should service and
repair heater.
POSSIBLE CAUSE
1. Ignitor electrode positioned wrong
2. Ignitor electrode broken
3. Ignitor electrode not connected to igni-
tor cable
4. Ignitor cable pinched or wet
5. Piezo ignitor nut is loose
6. Broken ignitor cable
7. Bad piezo ignitor
1. Gas supply turned off or equipment
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
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 con-
trol valve
6. Pilot flame not touching thermocouple,
which allows thermocouple to cool,
causing pilot 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
7. Thermocouple damaged
8. Control valve damaged
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REMEDY
1. Replace ignitor
2. Replace ignitor
3. Reconnect ignitor cable
4. Free ignitor cable if pinched by any
5. Tighten nut holding piezo ignitor to
6. Replace ignitor cable
7. Replace piezo ignitor
1. Turn on gas supply or open equipment
2. Turn control knob to PILOT position
3. Press in control knob while in PILOT
4. Continue holding down control knob.
5. Clean ODS/pilot (see Cleaning and
6. Replace gas regulator
1. Press in control knob fully
2. After ODS/pilot lights, keep control
3. Wait one minute for safety interlock sys-
4. Fully open equipment shutoff valve
5. Hand tighten until snug, then tighten 1/4
6. A) Contact local natural gas company
7. Replace thermocouple
8. Replace control valve
16
CAUTION: Never use a wire,
needle, or similar object to clean
ODS/pilot. This can damage ODS/
pilot unit.
metal or tubing. Keep ignitor cable dry
heater cabinet. Nut is located inside
heater cabinet at top
shutoff valve
position
Repeat igniting operation until air is re-
moved
Maintenance, page 19) or replace ODS/
pilot assembly
knob pressed in 30 seconds
tem to reset. Repeat ignition operation
turn more
B) Clean ODS/pilot (see Cleaning and
Maintenance, page 19) or replace ODS/
pilot assembly
107097