Fleck 27077 - Electronic Piston Assembly 4600SXT/5600SXT/6600/6700 Down Flow

The Fleck 27077 is the genuine electronic piston assembly fitted to down flow versions of the Fleck 4600SXT, 5600SXT, 6600 and 6700 control valves, the component that physically routes water through service and regeneration inside your softener. WrekinWater stocks this exact piston for owners of these SXT electronic valves who are seeing leaks, poor regeneration or reduced water softness caused by internal valve wear rather than a fault with the display or transformer.

Technical specifications

Symptoms that mean you need this part

• Softened water quality declines even though the SXT display shows normal cycle timings
• Water leaking from the valve body during or between regeneration cycles
• A gritty or scraping feel when the piston is manually moved during servicing
• Visible pitting, scoring or worn seals on the piston when the valve is opened up

Why it fails / why it matters

The piston in these electronic SXT valves is driven back and forth by the motor thousands of times a year to switch the water path between service, backwash, brine draw and rinse. Constant movement against the valve bore, combined with grit and mineral fines carried in the incoming water, gradually wears the piston surface and its rubber seals. Once the seals lose their shape, water can bypass internally or leak externally, so the electronic timer can be working perfectly while the valve itself no longer directs water correctly through the regeneration sequence.

Why buy this from WrekinWater

WrekinWater has served more than 50,000 customers over 15 years from our base in Bettisfield, Shropshire, and we stock genuine Pentair Fleck parts alongside Autotrol, Clack and Kinetico components, so you're getting an exact match for your down flow SXT valve rather than a part that's close but not quite right. Rated "Excellent" on Trustpilot, we're happy to help confirm your valve model before you order.

How to fit it

1. Isolate the water supply and, if fitted, switch the valve to bypass.
2. Relieve any residual pressure in the valve via a nearby tap.
3. Remove the valve body cap or retaining clip to access the piston assembly.
4. Withdraw the old piston and compare its seal stack against the new 27077 to confirm the match.
5. Fit the new piston, ensuring all seals sit correctly in the valve bore, then refit the cap.
6. Restore the water supply and run a manual regeneration on the SXT controller to check smooth cycling and no leaks.