Loud banging or knocking noises in pipes when the softener regenerates

Safety first: Do not open pressurized components while the unit is regenerating. Allow the cycle to finish first.

• Check mains pressure: Measure or have a plumber measure the incoming water pressure. Install or adjust a pressure reducing valve if pressure is above manufacturer limits.
• Inspect pipe supports: Ensure pipes around the softener are properly clipped and supported to reduce movement.
• Adjust regeneration flow: In the installer menu, reduce backwash and rinse flow rates if the model allows, within Viessmann specifications.
• Install water hammer arrestors: If noise persists, have a plumber install water hammer arrestors near the softener or at problem fixtures.