E11 error and water remains in drain line after regeneration, or drain runs continuously

Safety first: Close inlet and outlet valves and unplug the unit before opening the control valve. Expect some water discharge when removing components.

Step-by-step:

• Check drain line: Ensure the drain line is not kinked, frozen, or blocked. A blocked drain can cause the valve to stall.
• Inspect piston movement: Remove the AquaUnique control head cover and observe the cam/piston during a manual regeneration. If it does not move through positions, the piston may be stuck.
• Clean debris: Shut off water and relieve pressure. Remove the piston and seal pack according to the service manual. Rinse off resin beads, sand, or scale. Do not scratch sealing surfaces.
• Replace seals if worn: If seals are swollen, torn, or flattened, install a new AquaUnique seal and spacer kit.

When to call a technician: If the valve still cannot find the correct position or E11 persists, the position sensor or control valve body may need professional replacement.