Vaillant Electrical Noise / Relay Chatter

Vaillant smart thermostat or gateway emits a buzzing or clicking noise during operation.

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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

Relay rapidly switching due to unstable control signal, Loose transformer or inductor vibrating, Incorrect load connected to low‑power output, Supply voltage fluctuations

How to Fix / Troubleshooting

Safety: Isolate mains power before opening any housings.

  • 1. Identify source: Place your ear close (without opening) to determine if the noise comes from the thermostat, gateway, or wiring center.
  • 2. Check control settings: Reduce overly aggressive control parameters (e.g. very tight hysteresis) that may cause rapid switching.
  • 3. Verify load: Ensure that only appropriate low‑power control circuits are connected to the thermostat outputs, not pumps or large valves directly.
  • 4. Check supply stability: Have an electrician verify that the mains supply is stable and within tolerance.
  • 5. Replace noisy module: If a particular relay or transformer is mechanically noisy, replacement of the thermostat or gateway may be required.
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Repair Difficulty

Medium 3/5

Required Part

Vaillant smart thermostat / wiring center relay
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