Boiler runs but room temperature overshoots the thermostat setting, house becomes too hot.
Safety Warning
This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.
If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.
Possible Causes
How to Fix / Troubleshooting
Safety first: Overheating rooms is uncomfortable but not usually dangerous; however, do not cover radiators or block vents.
Homeowner checks:
- Turn the room thermostat down to minimum and see if the boiler shuts off after a short delay.
- Check programmer settings to ensure heating is not set to constant ON.
Engineer actions:
- Test room thermostat operation and replace if it does not open on temperature rise.
- Check wiring at the boiler and controls for incorrect links or permanent live to the call-for-heat terminal.
- Inspect the Worcester PCB for a stuck relay controlling the heating demand.
Correct control wiring and functioning thermostats are essential for comfort and efficiency.
Repair Difficulty
Required Part
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