FLECK 18052 - Fleck 9500 Piston - Upper

The Fleck 18052 upper piston is a genuine replacement part for the Fleck 9500 control valve, a duplex/high-flow valve widely used on commercial and larger residential softener and filter installations, and WrekinWater carries it as a direct fit for engineers and DIY-confident owners looking to resolve piston-related faults without replacing the whole valve.

Technical specifications

Symptoms that mean you need this part

• A continuous trickle or steady flow of water running to drain outside of a regen cycle
• The valve failing to complete or advance through its regeneration steps
• Grinding, sticking or jamming noises when the piston attempts to move
• Reduced or fluctuating water flow through the system during normal service

Why it fails / why it matters

The upper piston sits inside the valve body and moves back and forth to open and close the internal ports that direct water through service, backwash, brine draw and rinse. Constant movement against the seals and spacers wears the piston's sealing surfaces over time, and any grit, iron or scale carried in the water can score the plastic or cause it to bind, so the piston either stops sealing properly (leading to water leaking to drain) or stops moving cleanly (leading to a valve that jams mid-cycle).

Why buy this from WrekinWater

WrekinWater has served more than 50,000 customers over 15 years and, based in Bettisfield, Shropshire, stocks genuine parts for Fleck, Autotrol, Clack, Kinetico and other major brands, including commercial valve components like the 9500 upper piston that are harder to source through general suppliers. As a UK company (No. 11000488) rated Excellent on Trustpilot, WrekinWater gives commercial operators and installers a dependable source for keeping duplex softener systems running.

How to fit it

1. Turn off the water supply and place the valve into bypass
2. Relieve system pressure before opening the valve body
3. Remove the retaining clip or cap and slide out the old upper piston assembly
4. Inspect the seals, spacers and piston bore for wear, scale or debris and clean as needed
5. Fit the new Fleck 18052 upper piston, lubricating with a food-safe silicone lubricant if recommended
6. Reassemble the valve, restore water supply, come off bypass and run a manual regeneration to confirm smooth cycling