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Troubleshooting Gravity Direct Vent Wall Furnace
SYMPTOM POSSIBLE CAUSE CORRECTIVE ACTION
1. Pilot will not stay lit after
carefully following
lighting instructions.
2. Pilot burning - no gas
to main burner.
3. Burner comes "On" but
goes "Off" after operating
for no apparent reason.
A. Thermocouple or gen-
erator producing insuffi-
cient millivoltage.
Check pilot flame - must impinge on thermocou-
pie or generator. Be sure thermocouple or generator
is fully inserted in bracket. Make sure pilot lighting
door is tightly closed.
B. Loose or dirtythermocou- Clean and/or tighten thermocouple or generator
pie or generator connec- connections at valve.
tions at gas valve.
C. Thermocouple or gen-
erator defective.
D. Grounded thermostat
lead wire (Wall ther-
mostat model).
E. Thermomagnet pilot
safety defective.
A. Manual valve not turned
to "On" position after
lighting pilot.
Check thermocouple with millivolt meter. Should
generate approximately 30 millivolts when not con-
nected to load. When connected to load, should
generate approximately 14 millivolts; if below 7
millivolts, replace.
Check generator with millivolt meter. Take reading
at generator terminals of valve with pilot burning
and thermostat contacts closed. Should be 140
millivolts or more.
Remove thermostat lead wires from valve terminals.
If pilot now stays lit, trace thermostat wiring circuit
for a ground. May be grounded to furnace or gas
supply.
Replace gas valve after above is checked out.
Turn gas valve knob to "On" position.
B. Temperature dial or ther- Set temperature dial or thermostat to a position call-
mostat not turned to a irtg for heat.
position calling for heat.
C. Plugged burner orifice. Check - clean or replace.
D Temperature dial out of See valve manufacturer's instructions.
calibration. (Bulb control
model.)
E. Mis-wired or broken ther- Check connections at valve terminals. Jumper
mostat wires. Defective across thermostat terminals on valve - if valve
thermostat. 0Nail thermo- operates check thermostat wires.
stat model.
F Pilot generator may not See 1A above.
be generating sufficient
millivoltage to open valve.
G. Defective valve. Replace.
A. Tubes not properly
installed.
B. Furnace may be
overrated.
Check vent tube and air inlet tube. Follow installa-
tion instructions. Be sure joints are tight and both
tubes are in place. Use only tubes furnished. Do
not extend tubes beyond original length.
Check for high pressure at valve - see rating plate
for specified minimax supply pressure. Check
burner orifice.
(continued next page)
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