Elnur
Control Signal Failure
Boiler does not respond to room thermostat; heating stays on or off regardless of setting.
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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
Faulty room thermostat, Broken control wiring, Incorrect wiring at boiler terminals, Stuck relay on PCB
How to Fix / Troubleshooting
Safety first: Isolate power before working on control circuits.
- Test thermostat: Bypass the thermostat by linking the boiler's control terminals (as per manual) to see if the boiler responds. Remove the link after testing.
- Check wiring continuity: Use a multimeter to verify continuity of the thermostat cable between the boiler and thermostat.
- Inspect PCB relay: If the boiler stays on even with no demand, the heating relay on the PCB may be stuck closed and require board replacement.
- Replace thermostat: If wiring is intact but the thermostat does not switch correctly, fit a new compatible thermostat.
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Repair Difficulty
Medium
3/5
Required Part
Room Thermostat
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