Ngenic No Heat Output Despite Call-for-Heat

Heating does not turn on even though the thermostat shows a heating demand and target temperature above room temperature.

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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

Failed relay in Ngenic boiler interface module, Broken call-for-heat wiring between control module and boiler, Incorrect boiler terminals used (e.g., connected to low-voltage bus instead of room stat), Boiler internal fault unrelated to thermostat

How to Fix / Troubleshooting

Safety: Isolate mains power to the boiler and control module before touching any wiring.

  • Verify thermostat demand: Confirm the Ngenic app or thermostat shows an active heating demand.
  • Listen for relay click: When demand starts, listen near the Ngenic control module for a relay click. No click suggests a relay or control fault.
  • Check wiring: Compare the wiring between the Ngenic control module and boiler to both manuals. Ensure the correct room thermostat or OpenTherm terminals are used.
  • Test boiler manually (advanced): With power off, temporarily bridge the boiler’s room stat terminals (if safe and allowed by the boiler manual). Restore power; if the boiler fires, the issue is with the Ngenic control path.

If wiring is correct and the boiler responds to a manual bridge but not to Ngenic, the Ngenic boiler interface module likely needs replacement.

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Repair Difficulty

Professional Required 5/5

Required Part

Ngenic Boiler Interface / Control Module
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