Softener emits a persistent humming noise even when not regenerating

Safety first: Disconnect power before touching internal components.

• Identify source: With the cover removed (and power briefly restored), carefully listen to locate the hum (transformer, motor, or vibrating panel). Then disconnect power again.
• Tighten mounts: Secure any loose transformers, motors, or control boards with appropriate screws or clips.
• Isolate vibration: Add rubber washers or pads between vibrating components and the cabinet if recommended by Viessmann.
• Replace noisy component: If the transformer or motor is excessively loud, replace the Viessmann power transformer or motor assembly as appropriate.