Sterling QVSD - Manual (Page 25)

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1. Close air shutter. Refer to
“Operation”.
2. Clean main burner ports.
3. Reset manifold pressure. Refer
to
“Operation”.
4. Supply piping is inadequately
sized. Refer to “Installation”.
5. Clean pilot orifi ce. Refer to
“Operation”.
6. Eliminate drafts. Refer to
“Installation”.
7. Refer to ˆ“Installation”.
1. Open all manual gas valves.
2. Replace fuse or turn on power
supply.
3. Turn up thermostat.
4. Check limit switch with continuity
tester. If open, replace high limit.
5. Check wiring per wiring diagrams.
6. Replace gas valve.
7. Check thermostat and replace if
defective.
8. Be sure 115 volts is supplied to
the transformer primary, then
check for 24 volts at secondary
terminal before replacing.
9. Check and tighten all wiring
connections per diagrams.
10. Replace, if necessary. Also see
W, X, & Y symptoms.
1. Refer to “Installation, Venting”.
1. Relocate thermostat away from
drafts.
2. Replace thermostat.
3. Check wiring diagrams.
4. Check operation at valve.
Look for short (such as staples
piercing thermostat wiring) and
correct.
5. Replace gas valve.
6. Refer to “Operation”.
Table 9 - Troubleshooting Guide
SYMPTOMS POSSIBLE CAUSE(S) CORRECTIVE ACTION
1. Excessive primary air.
2. Main burner ports clogged near
pilot.
3. Pressure regulator set too low.
4. Pilot decreases in size when
main burners come on.
5. Pilot fl ame too small.
6. Drafts around ventor.
7. Improper venting.
1. Main gas valve off.
2. Lack of power at unit.
3. Thermostat not calling for heat.
4. Defective limit switch.
5. Improper thermostat or
transformer wiring at gas valve.
6. Defective gas valve.
7. Defective thermostat.
8. Defective transformer.
9. Loose wiring.
10. Defective ignition control.
1. Condensation of water vapor.
1. Poor thermostat location.
2. Defective thermostat.
3. Improper thermostat or
transformer wiring at gas valve.
4. Short circuit.
5. Defective or sticking gas valve.
6. Excessive gas supply pressure.
G. Delayed ignition.
H. Failure to ignite.
J. Condensation of water
vapor.
K. Burner won't turn off.