Safety Protocol & Classification
Safety Classification: CALL-A-PRO
Homeowner DIY Checks Allowed: NO — Professional Technician Required
What This Symptom Means
The boiler control attempted to light the burner but failed to detect a stable flame signal, causing a hard lockout safety shutdown.
Likely Causes
- Closed gas shutoff valve or low gas supply pressure.
- Fouled, oxidized, or mis-gapped ignition electrode or flame sensing rod.
- Defective automatic gas valve or ignition transformer.
- Blocked intake or exhaust venting preventing proper combustion airflow.
- Condensate drain line backup tilting water into heat exchanger.
Homeowner Inspection Boundaries
Because this symptom directly involves sealed pressure vessels, gas combustion, high-voltage circuits, or boiler safety limit devices, homeowner DIY disassembly or internal testing is not permitted under Hydronic Authority safety guidelines. Homeowners should observe external indicators (such as display codes or pressure gauges) and contact a certified hydronic technician.
What NOT To Do
- Do not repeatedly reset the boiler control after ignition lockout (can cause dangerous fuel accumulation).
- Do not open sealed combustion chamber covers.
- Never smell gas and remain inside the building — evacuate immediately if gas odor is present.
When to Call a Professional
Ignition lockouts involve gas combustion and high voltage. Call a licensed technician to inspect gas pressure, clean electrodes, and clear vent obstructions.
Error Code Cross-Reference
If your boiler display is showing an error code or fault message associated with this symptom, look up the code in the Phillips Hydronics Error Code Library for exact manufacturer actions.
Related Equipment & Component Guides
Sources & Documentation
- error-codes.json — Compiled across 12 boiler brand fault code tables
- hydronic-authority/boiler-troubleshooting.html —