Heatmiser
Boiler Interlock / Control Signal Failure
Thermostat shows correct status but boiler does not fire
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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
Open circuit between wiring centre and boiler, Boiler external controls not configured, Faulty boiler relay in wiring centre, Incorrect boiler terminal used
How to Fix / Troubleshooting
Safety first: Isolate power to boiler and wiring centre before testing continuity.
Steps:
- Confirm that the Heatmiser wiring centre's boiler enable output is wired to the correct boiler control terminals (e.g., room stat or external control contacts).
- With a thermostat calling for heat, check for voltage or continuity at the boiler enable terminals.
- If the wiring centre output is not switching, test the boiler relay on the wiring centre; replace the wiring centre if the relay has failed.
- Ensure the boiler is configured to accept external control and that any internal timers are set to allow demand from the Heatmiser system.
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Repair Difficulty
Hard
4/5
Required Part
Heatmiser Wiring Centre (Boiler Relay)
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