Thermostat emits a constant or intermittent clicking or buzzing noise during operation.

Safety first: Clicking is usually normal relay operation, but buzzing may indicate an electrical issue. Isolate power before opening the thermostat or wiring centre.

Steps to diagnose and fix:

• 1. Identify source: Determine whether the noise comes from the thermostat, wiring centre, or actuators.
• 2. Check load type: Ensure that the connected load (e.g., pump, valve) is suitable for electronic control and within the rated current of the thermostat or wiring centre.
• 3. Adjust control mode: If PWM control is causing audible noise in actuators, switch to on/off control if allowed by Danfoss for your system.
• 4. Tighten mounting: Secure the thermostat and wiring centre firmly to reduce vibration noise.
• 5. Replace noisy relay: If a relay is chattering or buzzing continuously, the coil or contacts may be failing. Replace the thermostat or wiring centre module containing the relay.

When to call a professional: Persistent buzzing or signs of overheating require immediate attention from an electrician or heating engineer.