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Troubleshooting
... (cont.)
SYMPTOM
4. Furnace oper_es
but
turns "Off"
before room
temperature
is attained,
5. Furnace not producing
sufficient heat.
6. Furnace operates but will
not shut "Off" when room
temperature
is attained.
7. Pilot outage problem.
8. Abnormal
operation.
A.
POSSIBLE CAUSE
Sensing bulb not located
properly. (Bulb control
model.)
CORRECTIVE ACTION
Check location of sensing bulb - should be attach-
ed to back of control valve.
B. Temperature dial out of
See valve manufacturer's
instructions.
calibration.
(Bulb control
model.)
C. Thermostat
location.
Check thermostat location - should not be in the
(Wall thermostat model.)
path of warm air discharge from furnace, near a
lamp, or above a T_/. or stereo set.
Defective thermostat.
Check thermostat calibration or replace.
(Wall thermostat model.)
Furnace may be too small
for space being heated.
O.
A.
B.
A.
Furnace not burning at
full rate.
Sensing bulb not located
properly. (Bulb control
model.)
Check heat loss calculations.
E
G.
A.
Check for low gas pressure (see 3B page 19).
Check burner office.
Check location of sensing bulb - should be attach-
ed to back of control valve.
B. Temperature dial out of
See valve manufacturer's
instruction.
calibration.
(Bulb control
model.)
C. Bulb or capillary broken.
Replace valve.
(Bulb control model.)
D. Thermostat wiring defec-
Thermostat
lead wires may be shorted together
tive. (Wall thermostat
caused by a nail or staple - check by removing ther-
model.)
mostat leads from valve terminals.
E. Thermostat
location.
Check thermostat location - if on an outside wall
(Wall thermostat model.)
or a hole in wall behind thermostat is causing cold
air to contact thermostat - relocate.
Defective thermostat.
Check thermostat calibration or replace.
(Wall thermostat model.)
Dirt under valve seat or
Replace valve.
valve stuck open.
A.
B,
Pilot flame may be low
or blowing (high) caus-
ing safety to drop out.
Delayed ignition - pilot
flame may be too low.
Expansion noise ticking.
Adjust pilot flame. Check vent tube and air inlet tube
(see 3A page 19). Be sure pilot lightingdoor is clos-
ed. Pilot orfice or aerating hole may be plugged
(check for spiders, webs or other organic material).
Adjust pilot flame.
Check installation - casing may be distorted by be-
ing fastened to an uneven wall. Vent tube and air
inlet tube may be in a bind with vent cap assembly
- be sure hole through wall is correct and parts fit
without binding.
-20-
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