Sterling GG-120 User Manual

34

 1. 

Check for proper orifi ce size. Refer to “Operation”.

 2. 

 

Test and reset manifold pressure.

 1. 

Replace 

orifi 

ce. 

  2. Test and reset manifold pressure.

  1. Clean main burner ports.
  2. Align manifold assembly.
  3. Clean combustion air inlet openings.
  4. Check gas input and manifold pressures.

  1. Clean Flue. Refer to “Installation”.
  2. Clean combustion air inlet openings.
  3. Clean heat exchanger. Refer to “Installation”. 
  4. Determine cause and repair accordingly.

  1. Inspect all gas piping and repair.
  2. Check to ensure gas test ports are seated.
  3. Clean heat exchanger/fl ue.
  4. Clean fl ue collector. 
 5. 

See 

“Installation”.

  1. Check grounding wires and spark bracket 

connections.

  2. Inspect spark cable connections and cuts.
  3. Check to ensure spark is energized after 

pre purge period.

  4. Test and reset manifold pressure refer to 

“Operations”.

  5. Clean or replace orifi ce.
 6. 

Refer 

to 

“Installation”.

  1. Open all manual valves “check for leaks”.
  2. Turn on power supply, check fuses and 

replace if bad.

  3. Turn up thermostat, Check for 24v on 

terminals R and W1 on terminal strip.

  4. Check switch for continuity if open with no 

heat present, replace.

  5. Check switch operation to ensure 

switch closes after draftor purge period. 
If it does not make/check tubing 
connections/blockage.

  6. Check all wiring per diagram.
  7. Check all ground wires and connections.
  8. Check both, for wiring according to diagram.
 9. 

Replace 

ignitor.

  10. Resecure ignitor bracket.
  11. Check for 24V at gas valve terminals during 

trial for ignition period. If present with no 
manifold pressure. Replace valve.

  12. Refer to symptom “Q”.

 1. 

Refer 

to 

“Installation, 

Venting”.

  2. Check gas supply pressures to unit. Refer 

to “Installation”.

 3. 

Refer 

to 

“Installation”.

  1. Burner orifi ce incorrect.
  2. Low manifold Pressure.

 1. 

Irregular orifi ce causing whistle or resonance.

  2. Excessive gas input.

 1. 

Clogged 

burner.

 2. 

Misaligned 

orifi 

ce.

  3. Insuffi cient combustion air.
  4. Possibly over fi red.

 1. 

Blocked 

venting.

  2. Insuffi cient combustion air.
  3. Blocked heat exchanger.
  4. Air leak into combustion chamber, fl ue 

collector or draft hood.

  1. Gas pipe leak. 
  2. Leaking gas test port on valve.
  3. Blocked heat exchanger.
  4. Blocked draft hood.
  5. Negative pressure in the building.

 1. 

Improper 

ground.

  2. Bad or broken spark cable.
 3. 

Faulty 

control.

  4. Manifold pressure set too low.

  5. Main burner orifi ce dirty.
 6. 

Improper 

venting.

  1. Gas supply is off.
  2. No power supply to unit.

  3. Thermostat not calling.

  4. Defective high limit.

  5. Defective drafter prove switch.

 6. 

Loose 

wiring.

 7. 

Improper 

ground.

  8. Improper thermostat or transformer wiring.
 9. 

Ignitor 

defective/damaged.

 10. Misaligned ignitor.
  11. Defective gas valve.
  

 

 12. Blown fuse.

 1. 

Improper 

venting. 

  2. Unit under fi red.

  3. Building too cold.

  A. Flame pops back.

 B. 

Noisy 

Flame.

  C. Yellow tip fl ame (some yellow 

tipping on LP gas is permissible).

 D. 

Floating 

fl 

ame.

 
 E. 

Gas 

odor.

     Shut off gas supply immediately! 

 F. 

Delayed 

ignition.

  G. Failure to ignite.

 H. 

Condensation.