Vanguard Heating VMH3000TNSA - Manual (Page 16)

16 107101
NATURAL GAS RESIDENTIAL HEATERS
®
For more information, visit www.desatech.com
TROUBLESHOOTING
WARNING: Turn off and un-
plug heater and let cool before
servicing. Only a qualified ser-
vice person should service and
repair heater.
REMEDY
1. Replace ignitor
2. Replace ignitor
3. Reconnect ignitor cable
4. Free ignitor cable if pinched by any
metal or tubing. Keep ignitor cable dry
5. Tighten nut holding piezo ignitor to
heater cabinet. Nut is located inside
heater cabinet at top
6. Replace ignitor cable
7. Replace piezo ignitor
1. Turn on gas supply or open equipment
shutoff valve
2. Turn control knob to PILOT position
3. Press in control knob while in PILOT
position
4. Continue holding down control knob.
Repeat igniting operation until air is re-
moved
5. Clean ODS/pilot (see Cleaning and
Maintenance, page 19) or replace ODS/
pilot assembly
6. Replace gas regulator
1. Press in control knob fully
2. After ODS/pilot lights, keep control
knob pressed in 30 seconds
3. Wait one minute for safety interlock sys-
tem 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 natural gas company
B) Clean ODS/pilot (see Cleaning and
Maintenance, page 19) or replace ODS/
pilot assembly
7. Replace thermocouple
8. Replace control valve
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
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
CAUTION: Never use a wire,
needle, or similar object to clean
ODS/pilot. This can damage ODS/
pilot unit.
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.
www.desatech.com