Safety Protocol & Classification
Safety Classification: CALL-A-PRO
Homeowner DIY Checks Allowed: NO — Professional Technician Required
What This Symptom Means
The boiler system has stopped delivering heat entirely, resulting in cold radiators or floors throughout the structure.
Likely Causes
- Thermostat call failure (dead batteries, misconfiguration, broken wiring).
- Safety lockout on ignition failure, high-limit trip, or low water cut-off.
- Main electrical disconnect switch turned off or tripped breaker.
- Gas supply shut off or frozen regulator.
- Primary circulator pump motor failure.
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 press the control reset button repeatedly (more than once) after a hard lockout.
- Do not attempt to light pilot or burner manually on automatic ignition systems.
- Do not bypass safety limit switches or low water cut-offs.
When to Call a Professional
Call a professional technician immediately during freezing weather if a single control reset does not restore operation, or if error codes point to ignition, gas valve, or safety limit trips.
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
- hydronic-authority/boiler-troubleshooting.html —