Clack WS1 Control Valve Rebuild

Why this matters

The Clack WS1 control valve sits on roughly 60% of the residential softeners and filters sold under private-label brands in the U.S. (Water-Right, EcoWater, Charger, Watts, Pelican, Nelsen, Aquasure all OEM the WS1). When a WS1 valve loses regen, leaks past the piston, or sticks mid-cycle, the homeowner has hard water in 48 hours. A full rebuild kit (P/N V3174 for WS1, V3175 for WS1.25) restores the valve to factory-new mechanical condition and runs about an hour in the field. This guide walks the procedure for a standard WS1 1-inch valve - the WS1.25 and WS1.5 are mechanically identical except for the piston and spacer dimensions.

Identify the exact valve

Clack stamps the valve series on the back of the valve body, behind the bypass:

• WS1 - 1 inch, residential. Piston P/N V3174-01, spacer/seal kit V3174.
• WS1.25 - 1.25 inch, larger residential / light commercial. V3175.
• WS1.5 - 1.5 inch commercial. V3176.
• WS1.5T - 1.5 inch high-flow commercial. V3177.

The black drive cap also has a date stamp - a valve over 12 years old often needs the drive motor (V3107) and drive cap assembly (V3110) as well as the piston/seal kit.

Tools and parts to stage

• Correct rebuild kit (V3174 for WS1) - this includes piston, spacer, seal stack, drive cap O-ring.
• Clack silicone lubricant (P/N V3175-01) - the only approved lube; petroleum grease swells the seals.
• 7/16 inch open-end wrench
• Phillips screwdriver
• Bypass plug (V3151) or close the upstream shutoff
• Clean rags - the valve interior must be debris-free at reassembly
• Camera for documenting program settings before reset

Document the existing program

Before disconnecting power, write down every program setting. A factory-fresh control board reverts to defaults; restoring the wrong regen time or hardness setting after a rebuild is a callback. Press the SET CLOCK button, then the up arrow to walk through:

• Current time
• Regen time (typically 02:00)
• Days between regens or capacity / hardness setting
• Salt dose (lb per regen)
• Cycle times (Backwash, Brine Draw, Rapid Rinse, Brine Refill)
• Auxiliary outputs if used

Photograph each screen. Snap a photo of the salt-dose label on the brine tank too if present.

Put the valve in bypass

Pull the bypass handle (the white or red T-handle on the back of the valve) toward you to engage bypass mode. Confirm by opening a downstream tap - water continues to flow if bypass is engaged. On installs where the customer has external bypass valves, use those instead and confirm the WS1 bypass is in service position.

Unplug the WS1 transformer (24 VAC, 12 W typical) from the wall outlet.

Remove the drive cap

The drive cap is the curved black cover on top of the valve. Lift the cover off (snap-fit, no fasteners). Disconnect the three wire harnesses from the control board:

• Power harness (transformer)
• Drive motor harness (4-pin)
• Optional flow meter harness (3-pin) - keep oriented for reconnection

Remove the four Phillips screws holding the drive cap assembly to the valve body. Lift the drive cap straight up. The drive gear engages the piston rod; you may need to gently rotate the gear by hand to disengage cleanly.

Pull the piston

The piston rod protrudes through the top of the valve body. Grasp the rod with pliers wrapped in a rag (do not score the rod) and pull straight up. A stuck piston usually comes free with steady upward pressure; if it does not, attach a slide-hammer adapter (V3174-99 puller) or thread a 1/4-20 bolt into the tapped end.

Once the piston is out, the seal stack and spacer remain in the valve body. Pull the seal stack with the seal-and-spacer puller (V3194) - this is a $40 tool, but field-rebuilding without it leaves seals damaged in the bore.

Inspect the bore and components

Look down the valve bore with a flashlight:

• The bore should be smooth, no scoring. Light scratches are normal; deep grooves mean the entire valve body is condemned.
• Resin fines or sediment in the bore: the upstream pre-filter has failed or the resin tank's riser screen is broken. Flush with clean water and identify the upstream cause.
• Calcium scale: the inlet water has higher hardness than the softener can handle, or the softener has been in bypass for an extended period and city scale has packed the valve.

Inspect the removed piston. Black wear marks on the OD are normal; pits or gouges mean the new piston is required (it is in the kit). Compare the new piston length and OD to the old one - a WS1.25 piston dropped into a WS1 valve will bind on the first stroke.

Install the new seal stack

The seal stack is six EPDM lip seals separated by five plastic spacers. They press into the valve body in a specific orientation:

1. Apply a thin film of Clack silicone (V3175-01) to each seal lip and the bore. Do not over-lube; excess silicone migrates into the brine line and contaminates resin.
2. Stack the seals and spacers on the installation tool in the order shown on the rebuild-kit instruction sheet. The seal lips face the direction of fluid flow at that point in the cycle - reversed seals fail in days.
3. Press the stack into the bore using the installation tool, seating fully so the last spacer is flush with the top of the bore.

Install the new piston

Lubricate the piston rod with Clack silicone. Slide the piston straight down into the bore, rotating slightly if it catches a seal. The piston should travel freely without forcing - if it sticks, a seal is reversed or the piston is misaligned.

Bottom out the piston, then pull it back up to its home position. You should feel each seal pass over the piston with a smooth resistance.

Reassemble the drive cap

Set the drive cap onto the valve body, aligning the drive gear with the piston rod. Run the four Phillips screws in finger-tight, then snug in a star pattern - do not over-torque, the plastic strips at 5 in-lb. Reconnect the three harnesses to the control board in the same orientation you photographed.

Snap the cover back on.

Power up and re-enter the program

Plug the transformer back in. The display will boot to a Set Clock prompt with a flashing 12:00. Walk through the program using your saved photos:

1. Set current time.
2. Set regen time.
3. Set hardness / capacity.
4. Set salt dose.
5. Confirm cycle times (typically Backwash 10 min, Brine Draw 60 min, Rapid Rinse 10 min, Brine Refill calculated from salt dose).

Force a manual regen (press REGEN, hold for 3 seconds, the valve advances to the first cycle). Watch the valve move through Backwash, Brine Draw, Rapid Rinse, and Service. No leaks at the drive cap, no leaks at the drain line.

Return to service

References

• Clack WS1 Service Manual, Clack Corporation document WS1-SM Rev 6 (2023)
• NSF/ANSI 44-2023 - Residential Cation Exchange Water Softeners
• NSF/ANSI 372-2023 - Drinking Water System Components - Lead Content
• Clack Technical Bulletin TB-2022-04 - Seal Stack Orientation
• WQA Master Water Specialist Reference Manual, 2024 Edition, Section 4
• ANSI/NSF 60-2023 - Drinking Water Treatment Chemicals