Testing and thorough diagnostic are believed to require help of certified specialists. However, modern gas boilers are equipped with self-diagnostic systems, which report issues by showing error codes on the front panel display. The following table will help you identify the cause of your problem and solve it.
| PROBLEM | CAUSE | REMEDY |
|---|---|---|
| Burners fail to operate | 1. Safety pilot out, or flame too low. | 1. Check, clean, re-light. |
| 2. Gas supply valve shut off. | 2. Open gas valve(s). | |
| 3. Electric switch open. | 3. Close switch. | |
| 4. Blown or defective line fuse. | 4. Replace fuse. | |
| 5. Operating or limit control contacts open or dirty. | 5. Check control. Clean contacts or replace control. | |
| 6. Defective gas valve or pressure regulator; or plugged bleed line. | 6. Repair or replace. | |
| 7. Defective low voltage transformer. | 7. Replace aquastat. | |
| 8. Obstruction at main burner orifice. | 8. Check, clean and reinstall. | |
| 9. Break in wiring or loose contact at control terminals. | 9. Check with test-light and correct. | |
| 10. Improper wiring. | 10. Check and correct in accordance with wiring diagrams included with appliance instructions. | |
| 11. Improper controls. | 11. Install proper controls. | |
| 12. Rollout or blocked vent safety switch open. | 12. Replace rollout switch (inspect flue passages prior to replacement) or reset blocked vent safety switch by depressing the reset button | |
| Burners will not shut off | 1. Defective operating control, gas valve, or high limit control. | 1. Check, repair or replace. |
| 2. Improper wiring or short circuit. | 2. Check wiring and controls. | |
| Flash back - burning at orifices | 1. Manifold gas pressure too low. | 1. Adjust to proper manifold pressure. |
| 2. Improper primary air adjustment. | 2. Adjust air to produce soft, clean flame. | |
| 3. Gas regulator bleed too slow. | 3. Adjust bleed opening. | |
| 4. Burrs on orifice. | 4. Remove burrs. | |
| 5. Improperly drilled orifice plugs. | 5. Install orifice plugs with proper drilling. | |
| 6. Leaking automatic gas valve. | 6. Repair or replace. | |
| 7. Adverse draft condition in boiler room. | 7. Check air supply and venting system. | |
| 8. Low main gas pressure. | 8. Contact utility. | |
| 9. Safety pilot improperly installed. | 9. Correct to manufacturer's recommendations. | |
| Delayed ignition | 1. Pilot flame too low. | 1. Increase gas supply to pilot. |
| 2. Pilot burner ports or pilot orifice clogged. | 2. Clean ports or orifices. | |
| 3. Burners or orifices out of alignment. | 3. Realign burners or manifold. | |
| 4. Excessive primary air. | 4. Adjust primary air shutters. | |
| 5. Excessive burner input. | 5. Check and reduce to input shown on rating plate. | |
| 6. Adverse draft condition in boiler room. | 6. Check air supply and venting system. | |
| Fumes and gas odors | 1. Leaks in gas piping or accessories. | 1. Locate leaks and repair. |
| 2. Gas leaks in service line or meter connections. | 2. Close service supply valve - shut down appliance and notify utility. | |
| 3. Blocked chimney. | 3. Check and repair chimney. | |
| 4. Boiler flueways blocked with soot. | 4. Clean flueways and adjust burners as described in the installation instructions. | |
| 5. Undersized breeching or too many turns in breeching. | 5. Check manufacturer's recommendations. | |
| 6. Adverse draft condition in boiler room. | 6. Check air supply and venting system. | |
| 7. Overfiring. | 7. Adjust gas input to that shown on boiler rating plate. | |
| Condensation in boiler flues or in vent system | 1. Underfiring. | 1. Increase firing rate to that shown on rating plate. |
| 2. Boiler water maintained at too low a temperature level. | 2. Set low limit controls to maintain a higher water temperature. If boiler is not equipped with low limit replace with one which has a combination low limit/high limit aquastat. | |
| 3. Long horizontal run of smokepipe. | 3. Relocate boiler or insulate breeching. | |
| 4. Inadequate chimney or venting system. | 4. Check chimney and venting recommendations |