The following troubleshooting table contains a list of the most common gas boiler issues and their solutions. By the signs described in the table, you can trace the cause. Solutions are described in the opposite column. Most problems can be solved without calling a technician.
Smith 88 boiler troubleshooting
| Problem | Possible Cause | Suggested Remedy |
|---|---|---|
| Pilot Outage | Defective Thermocouple | Replace |
| Heavy Draft Blowing across Pilot | Redirect Air Movement or Eliminate | |
| Plugged Pilot Orifice | Replace Orifice | |
| No Gas | Check Manual Pilot Valve Check Main Gas Shut-Off Valve Check Manual Meter Valve Consult Gas Company | |
| Defective Thermopilot Switch | Replace | |
| Defective Ignition Control | ||
| Main Gas Valve Will Not Open (Spark Ignited Pilot) | No Power | Check Power Source with Meter Check Fuses |
| Defective Gas Valve | Replace | |
| Low Water Level in Boiler or System Causing Low Water Cut-off to Function | Check for Leaks Check Feeder (if Supplied) | |
| Defective Ignition Control | Replace | |
| High Gas Pressure Switch Open (if Provided) | Check Switch Setting Check Manifold Gas Pressure | |
| Low Gas Pressure Switch Open (if Provided) | ||
| Main Gas Valve Will Not Open (Standing Pilot) | No Power | Check Power Source with Meter Check Fuses |
| Defective Gas Valve | Replace | |
| Pilot Out | Relight Pilot (May have defective pilot valve or relay) | |
| Low Water in Boiler or System Causing Low Water Cut-off to Function | Check for Leaks Check Feeder (if Supplied) | |
| Defective Thermopilot Switch | Replace | |
| Defective Thermocouple | ||
| High Gas Pressure Switch Open (if Provided) | Check Switch Setting | |
| Check Manifold Gas Pressure | ||
| Low Gas Pressure Switch Open (if Provided) | Check Switch Setting | |
| Check Inlet Gas Pressure | ||
| Burner(s) Burning with Yellow Flame | Air Adjustment Screws Turned in Too Far | Adjust Screws Out |
| Low Gas Pressure in Manifold (Insufficient Air Injection) | Adjust Main Gas Pressure Regulator or Check Line Pressure | |
| Burner Ports Partially Closed (Rust, Dirt, Lint, etc) | Replace Burners or Clean Ports | |
| Insufficient Air for Combustion | Check Size of Combustion Air Openings to Room If Undersized, Correct as Required Check for Negative Pressure in Boiler Room | |
| Oversized Burner Orifice | Install Correct Orifice | |
| High Gas Pressure in Manifold | Adjust Main Gas Pressure Regulator | |
| Gas Spillage from Draft Hood Relief Opening | Insufficient Draft - Chimney Too Low | Increase Height or Add Induced Draft Fan |
| Insufficient Draft - Chimney Too Small | Replace Chimney or Add Induced Draft Fan | |
| Insufficient Draft - Blockage in Chimney or Vent | Repair Chimney or Vent | |
| Insufficient Draft - Downdraft Caused by Chimney Location with Respect to Other Buildings, Roofs, etc. | Install Chimney Cap | |
| Negative Pressure in Boiler Room (Due to Exhaust Fan or Duct System) | Remove Exhaust Fan or Isolate Fan From Boiler Room | |
| Insufficient Combustion Air Openings | Provide Correctly Sized Combustion and Ventilation Air Openings | |
| Main Gas Valve Opens But No Gas Flows | Manual Valve Closed at Gas Train | Open Valve |
| Manual Valve Closed at Meter | ||
| Test Firing Valve Closed (if Provided) | ||
| Water Hammer On Start-Up | Sags in Steam Piping or not enough Pitch | Correct Piping Condition |
| Concentric reducers causing condensate pooling | Correct Piping | |
| Drip trap failed closed | Replace Trap or Trap Element | |
| Dry returns wetted due to new boiler water line higher than old boiler | Correct Piping or Install Feed System and Traps | |
| No drip line on the back side of a back-pitched motorized valve | Install Drip Line and Trap | |
| Water Hammer During Mid-Cycle | Clogged returns on gravity system | Clean or Re-Pipe Return Line(s) |
| Incorrect near-boiler piping causing wet steam to system | Correct Piping per Manual | |
| Trap failed open, allowing steam to enter returns | Replace Trap or Trap Element | |
| {Radiator Hammer} Large radiator may be vented too quickly | Use smaller Air Vent or Use Two Small Vents in Place of One Large Vent, One Mounted Higher than the Other | |
| Long nipple at Hartford Loop | Replace with Close Nipple | |
| Water leg or back slope in return line to receiver tank, causing water pocketing | Correct Piping | |
| Trap installed at receiver tank, causing water trapping in return | Remove Trap at Tank, Install Drip Traps and Radiator Traps where Required | |
| Boiler feed pump or condensate pump feed rate too fast, causing spraying into equalizer | Throttle Flow Rate | |
| No drip on the inlet side of a forward pitched motorized valve | Add Drip Line and Trap | |
| Uninsulated steam piping, causing excessive condensate loads | Insulate Steam Pipes | |
| Water Hammer on Shut-Down | Close nipple on Hartford Loop too high | Repipe 2" to 4“ (5cm to 10cm) Below Water Line |
| Uninsulated steam piping in boiler room, but system piping insulated, causing vacuum condition on shut-down | Insulate Steam Pipes | |
| Hammering in the Boiler | Poor circulation in the boiler due to sludge accumulation | Clean and Blowdown the Boiler |
| No Heat or Poor Heat Distribution in the Building | Main vents not working | Replace Main Vents, Repiping away from End of Lines if Needed |
| Drip Traps failed closed | Replace Traps or Trap Elements | |
| Radiator traps failed open, allowing pressurization of the returns | ||
| Water legs or back slope in return lines to receiver tank, preventing air from venting out receiver vent | Correct Piping | |
| Boiler pressure too high, causing air vents to lock up or blowing water loop seals | Reduce Operating Pressure | |
| System or Boiler Overfilling or Flooding | New boiler water content smaller than old boiler | Install Boiler Feed System with Receiver Tank Large enough for Condensate |
| Boiler water feed rate or pump rate too fast causing water level to collapse (due to collapse of steam bubbles in boiler water) | Reduce Feed Rate | |
| Foaming, priming or surging due to poor water quality | Clean the Boiler | |
| Excessive Water Level Bounce | Poor water quality, causing foaming and surging | |
| Incorrect near-boiler piping, such as undersized or incorrectly placed risers | Pipe per Manual | |
| Boiler water feed rate or pump rate too fast | Reduce Feed Rate | |
| Rapid Cycling | Air vents or traps not venting air, preventing steam from getting to radiation and pressurizing the air pocket | Replace Vents or Traps |
| Pressure differential on pressure control too close | Adjust Control Differential | |
| Nuisance outages of water level control due to boiler water level bounce | See Excessive Water Level Bounce Above |
Smith GB100 boiler troubleshooting
| PROBLEM | POSSIBLE CAUSES | CORRECTIVE ACTIONS |
|---|---|---|
| Burners not functioning. | 1. No power. | 1. Check line voltage wiring and fuses. |
| 2. Limit not working. | 2. Check wiring and contacts, relay, temperature setting. Clean and adjust as necessary. | |
| 3. Flame rollout switch open. | 3. Replace switch. Locate cause and correct. | |
| 4. Blocked vent switch open. | 4. Reset blocked vent switch. Locate cause and correct. | |
| 5. Gas off at boiler gas valve. | 5. Start boiler using Lighting/Operating Instructions. | |
| 6. Gas off external to boiler. | 6. Check any gas valves in the line. | |
| 7. Plugged orifice spuds. | 7. Check, clean and re-install. | |
| 8. Defective gas valve. | 8. Use Figure 8.1 to troubleshoot intermittent ignition gas valve. Replace if necessary. | |
| 9. Improper wiring. | 9. Check and correct. | |
| 10. Vent damper malfunctioning. | 10. Refer to vent damper manufacturer’s instructions. Replace if necessary. | |
| Burners will not shut down. | 1. Defective gas valve. | Troubleshoot intermittent ignition gas valve. Replace if necessary. |
| 2. Short circuit. | 2. Check and correct wiring. | |
| Flashback or burning at orifice spuds. | 1. Manifold gas pressure too low. | 1. Adjust to proper pressure. |
| 2. Improperly sized/drilled orifice spuds. | 2. Install correct spuds. | |
| 3. Leaking gas valve. | 3. Replace valve. | |
| 4. Burrs on orifice. | 4. Remove burrs. | |
| 5. Low supply gas pressure. | 5. Contact gas supplier if natural gas. Adjust regulator if LP gas. | |
| 6. Excessive downdraft or draft problems in boiler room. | 6. Check air supply, ventilation and venting system. | |
| Delayed ignition. | 1. Insufficient pilot flame. | 1. Increase pilot gas flow. |
| 2. Pilot bumer/orifice clogged. | 2. Clean pilot burner and orifice. | |
| 3. Overfiring. | 3. Reduce rate to input on rating label. | |
| 4. Misaligned burners or pilot. | 4. Realign burners or pilot. | |
| 5. Draft problem in boiler room. | 5. Check air supply, ventilation and venting system. | |
| Excessive condensation in vent. | 1. Underfiring. | 1. Increase rate to input on rating label. |
| 2. Limit (Aquastat) set too low. | 2. Reset Aquastat to higher setting. | |
| 3. Vent pipe too long. | 3. Reposition boiler to reduce length. | |
| 4. Inadequate chimney or venting system. | 4. Check chimney and venting recommendations. | |
| Boiler not heating properly. | 1. Underfiring. | 1. Increase rate to input on rating label. |
| 2. Limit set too low. | 2. Reset Aquastat to higher setting. | |
| 3. Air in system. | 3. Vent air from all points in system. | |
| 4. Circulator malfunctioning. | 4. Check circulator, replace if necessary. | |
| 5. Circulation system clogged. | 5. Shut down and cool boiler, drain and flush system. | |
| 6. Incorrect thermostat heat anticipator setting. | 6. Adjust heat anticipator. | |
| Fumes or gas odors | 1. Leaks in gas piping or fittings. | 1. Locate and repair or replace. |
| 2. Leaks in gas service line or meter. | 2. Shut down boiler and notify gas provider. | |
| 3. Obstructed chimney. | 3. Check, repair and/or clean chimney. | |
| 4. Obstructed flueways or vent. | 4. Clean flueways or vent and remove obstructions. | |
| 5. Undersized chimney or vent, high draft loss in vent. | 5. Check National Fuel Gas Code and vent manufacturer s recommendations. | |
| 6. Draft problem in boiler room. | 6. Check air supply, ventilation and venting system. | |
| 7. Overfiring. | 7. Reduce rate to input on rating label. | |
| 8. Vent damper malfunctioning. | 8. Refer to vent damper manufacturer’s instructions. Replace if necessary. |