44
MUA-SVX004B-EN
Symptoms
Possible Causes
Corrective Actions
Floating flame
1.
Blocked heat exchanger.
2.
Insufficient combustion air.
3.
Blocked venting.
4.
Air leak into combined chamber,
draft hood, or flue collector.
1.
Clean heat exchanger.
2.
Clean combustion air inlet
openings in bottom panel. Refer
to installation.
3.
Clean flue. Refer to installation
4.
Determine cause and repair
accordingly. Refer to
installation.
Burner won't turn off
1.
Poor thermostat location.
2.
Defective thermostat.
3.
Improper thermostat or
transformer.
4.
Short circuit.
5.
Defective or sticking gas valve.
6.
Excessive gas supply pressure.
1.
Relocate thermostat away from
drafts.
2.
Replace thermostat.
3.
Check wiring diagrams.
4.
Check operation at valve. Look
for short and correct (such as
staples piercing thermostat
wiring).
5.
Replace gas valve.
6.
Refer to operation.
Rapid burner cycling
1.
Loose electrical connections at
gas valve or thermostat.
2.
Excessive thermostat heat
anticipation.
3.
Unit cycling on high limit.
4.
Poor thermostat location.
1.
Tighten all electrical
connections.
2.
Adjust thermostat heat
anticipation for longer cycles.
Refer to operation.
3.
Check for proper air supply
across heat exchanger.
4.
Relocate thermostat. (Do not
mount thermostat on unit).
Not enough heat
1.
Incorrect gas input.
2.
Heater undersized.
3.
Thermostat malfuction.
4.
Heater cycling on limit control.
5.
Check outside dampers if used.
1.
Refer to operation.
2.
This is especially true when the
heated space is enlarged. Have
the heat loss calculated and
compare to the heater output
(80% of input). Your gas
supplier or installer can furnish
this information. If heater is
undersized, add additional
heaters.
3.
Replace thermostat.
4.
Check air movement through
heat exchanger. Check voltage
to power venter motor, clean
power venter wheel and heat
exchanger, and oil power venter
motor. Check filters, replace if
necessary.
5.
Adjust dampers accordingly.
Too much heat
1.
Thermostat malfunction.
2.
Heater runs continuously.
a.
Improper thermostat or
transformer wiring at gas
valve.
b.
Short circuit.
c.
Defective or sticking gas
valve.
d.
Excessive gas supply
pressure.
1.
Replace thermostat.
2.
a.
Check wiring per diagrams.
b.
Check operation at valve.
Look for short and correct
(such as staples piercing
thermostat wiring).
c.
Replace gas valve.
d.
Refer to operation.
