Radiator / heating symptoms / heating output
Why is the heating on but the radiators are cold?
Start with the observable symptom. This page explains possible causes; it is not a diagnosis.
If the heating is calling but radiators stay cold, check the thermostat, programmer, boiler display and pressure before assuming a radiator problem. A system-wide fault, low pressure, pump or control issue needs a heating engineer.
Start with the pattern.
The controller appears to call for heat but several or all radiators remain cold.
Possible causes, not a diagnosis.
- The thermostat or programmer is not actually requesting central heating.
- Boiler pressure, an error state, pump or control fault is stopping circulation.
- A valve or zone control may be closed or stuck.
Check what is safe to observe.
- 01
Check the heating schedule, room thermostat and any holiday or override setting.
- 02
Read the boiler display and pressure gauge using the manufacturer’s guidance.
- 03
See whether hot water works and whether any radiator warms at all.
Take the smallest useful step.
- Use normal controls and the manufacturer’s permitted reset only.
- Keep boiler vents and controls accessible without opening the case.
- Contact the landlord or housing provider or engineer if the fault affects the whole home.
- Do not repeatedly reset the boiler when the cause is unclear.
- Do not remove panels or interfere with gas, electrical or safety parts.
- Use an appropriately licensed gas professional in the UK (Gas Safe registered engineer) for a gas boiler fault or repeated lockout.
- Report loss of heating promptly to a landlord or housing provider, especially in cold weather.
Professional requirements and rental responsibilities vary by location. Use the qualified local professional or housing authority that applies where you live.
UK example: Gas Safe RegisterWhy this page says that.
This page separates an observable symptom from possible causes and keeps the recommended action within a safe household boundary.