Display shows “Err 3” and regeneration will not start or stops immediately.

Safety: Disconnect power, close inlet, open bypass, and relieve pressure by opening a nearby faucet before disassembling the valve.

Steps:

• Depressurize the valve: After bypassing, open a soft water faucet to relieve pressure. Confirm there is no pressure at the valve before removing any clips.
• Remove the piston and seal pack: Take off the valve cover. Remove the retaining clips and pull out the Clack main piston and seal/spacer stack as a unit, following the service manual.
• Inspect components: Check the piston for scoring, swelling, or cracks. Inspect seals and spacers for deformation, cuts, or resin grains lodged between them. Any binding can prevent full travel and trigger Err 3.
• Clean the valve body: Rinse the valve bore with clean water to remove resin fines or debris. Do not scratch the bore surface.
• Replace worn parts: If seals are worn or the piston is damaged, install a new Clack piston and seal/spacer kit matched to your valve model (e.g., WS1, WS1.25, WS1.5).
• Reassemble and test: Lubricate O-rings with NSF-approved silicone grease only. Reinstall the piston and seals, reattach clips, restore water (take out of bypass), check for leaks, then restore power and run a manual regeneration to confirm normal travel.

Warning: Forcing a stuck piston with tools can crack the valve body. If the piston will not come out easily, consult a professional.