Worcester Bosch
Stuck call for heat
Heating stays on constantly even when thermostat is set low or turned off.
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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.
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Possible Causes
Stuck relay contacts in receiver, Shorted call‑for‑heat wiring, Motorised valve end‑switch stuck closed, Thermostat incorrectly wired in 'always on' configuration
How to Fix / Troubleshooting
Safety first: Turn off heating power at the fused spur before investigating wiring or valves.
- Confirm thermostat setting: Set thermostat to 'Off' and minimum temperature. If boiler still runs, the issue is downstream.
- Check receiver: With power off, inspect the receiver for signs of overheating. If the relay is suspected stuck, the receiver should be replaced.
- Zone valves: For systems with motorised valves, check if any valve manual lever is latched open. Release it and see if heating stops when power is restored.
- Wiring inspection: A qualified engineer should check for a short between live and call‑for‑heat terminals.
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Repair Difficulty
Professional Required
5/5
Required Part
Worcester Bosch RF Receiver Module
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