Worcester Bosch
Flow control or zoning fault
Boiler fires but radiators do not get hot in the zone controlled by the smart thermostat.
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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
Closed radiator valves, Stuck TRVs, Motorised valve not opening, Incorrect zone assignment in controller
How to Fix / Troubleshooting
Safety first: Pipework may be hot; use caution when touching valves.
- Check radiator valves: Ensure all manual valves and TRVs in the affected zone are open.
- Zone valve operation: Locate the zone valve for that circuit. With a call for heat, feel if the pipe after the valve gets hot. If not, the valve may be stuck closed.
- Manual override: Use the valve's manual lever to open it temporarily and see if radiators heat. If they do, the actuator may be faulty.
- Zone configuration: Verify in the smart controller that the thermostat is assigned to the correct zone outputs.
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Repair Difficulty
Medium
3/5
Required Part
Motorised Zone Valve Actuator
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