Vaillant Bypass Left Engaged After Installation or Service

Softener installed but water remains hard because unit is in permanent bypass

Possible Causes

Bypass valve not returned to service position, Installer left isolation valves closed, Misunderstanding of valve positions by user

Safety: Ensure you understand the valve layout before changing positions to avoid leaks or isolation of the property supply.

Steps:

Identify valves: Locate the inlet, outlet, and bypass valves on the Vaillant softener manifold.
Set to service: Follow the manual to set the valves to the normal service position (typically inlet and outlet open, bypass closed).
Test hardness: After a few minutes of flow, test softened water hardness to confirm the softener is now in line.

Very Easy 1/5