Autotrol 1235340 Top plate for 255 700 Series

The 1235340 is the top plate fitted to Autotrol 255 and 700/Logix series control valves, sitting over the piston and drive assembly and retaining the piston spring within the valve body. It's a structural cover rather than a wearing seal, but it takes the strain every time the piston cycles and can crack or fail with age or from over-tightened fixing screws. WrekinWater stocks this top plate for engineers and DIY customers repairing a leaking or damaged valve head.

Technical specifications

Symptoms that mean you need this part

• Water weeping from around the top of the valve body near the drive or motor mounting
• The piston spring has popped out of place or the piston doesn't return smoothly during a cycle
• Visible cracking around the fixing screw bosses on the top plate
• The top plate has been over-tightened or cross-threaded during a previous repair and no longer seats flat

Why it fails / why it matters

The top plate closes off the top of the valve body, holding the piston spring under tension and keeping the internal water pathway sealed at the top of the stack. Because it's held down by a ring of screws, over-tightening during a previous service is a common cause of hairline cracks around the screw bosses, and once cracked the plate can't maintain the seal or contain the piston spring properly. A failing top plate typically shows up as a slow weep near the top of the valve or a piston that doesn't cycle cleanly, and since it's a moulded assembly rather than a simple seal, replacement is the only fix.

Why buy this from WrekinWater

WrekinWater has supplied Autotrol control valve components including structural parts like this top plate for over 15 years from its Bettisfield, Shropshire base, working with more than 50,000 customers who need the exact fit for their valve generation. As UK Company No. 11000488 and a specialist stockist of Pentair Fleck, Autotrol, Clack and Kinetico parts rated Excellent on Trustpilot, WrekinWater is set up to get parts like this to you before a leak becomes a bigger repair.

How to fit it

1. Isolate the mains supply and switch the softener to bypass before starting work
2. Remove the fixing screws holding the existing top plate to the valve body, working in a criss-cross pattern to release it evenly
3. Lift off the old top plate carefully, noting how the piston spring sits underneath
4. Inspect the piston and spring for wear or damage while the plate is off
5. Fit the new 1235340 top plate, ensuring the piston spring is correctly located before closing it down
6. Refit and tighten the screws evenly and just firmly enough to seal, then restore the mains supply and check for leaks