Sterling QVSD - Manual (Page 26)

26
Table 9 - Troubleshooting Guide
SYMPTOMS POSSIBLE CAUSE(S) CORRECTIVE ACTION
1. Loose wire connections at gas
valve or thermostat.
2. Excessive thermostat heat
anticipator.
3. Unit cycling on high limit.
4. Poor thermostat location.
5. Draft on pilot.
6. Defective ignitor control.
7. Defective high limit.
1. Power ventor wheel loose.
2. Power ventor wheel dirty.
3. Power ventor wheel rubbing
housing.
4. Bearings are dry.
1. Main gas valve off.
2. Pilot adjustment screw turned
too low on combination main gas
valve.
3. Air in gas line.
4. Incorrect lighting procedure.
5. Dirt in pilot orifi ce.
6. Extremely high or low gas
pressure.
7. Drafts around unit.
8. Pilot valve not opening (faulty
wiring).
9. No spark (faulty wiring).
10. Defective gas valve.
1. Tighten all connections.
2. Adjust thermostat for longer
cycles. Refer to “Operation”.
3. Check for proper air supply
across heat exchanger.
4. Relocate thermostat (do not
mount thermostat on unit).
5. Eliminate drafts. Refer to
“Installation”.
6. Replace ignitor.
7. Jumper high limit switch terminals
1 and 2. If burner operates
normally, replace switch.
1. Replace or tighten.
2. Clean power ventor wheel.
3. Realign power ventor wheel.
4. Oil bearings on power ventor
motor. Refer to label on motor.
1. Open all manual gas valves.
2. Refer to “Operation”.
3. Purge air from gas line.
4. Follow lighting instruction label
adjacent to gas valve.
5. Remove pilot orifi ce. Clean with
compressed air or solvent. Do
not ream.
6. Refer to “Operation”.
7. Eliminate drafts. Refer to
“Installation”.
8. Inspect and correct wiring.
9. Inspect and correct ignition
system wiring. See symptoms
W, X & Y.
10. Replace gas valve.
L. Rapid burner cycling.
M. Noisy power ventor.
N. Pilot will not light or will not
stay lit.