Autotrol Top plate for 255 400 Series to convert to Single Spring

This top plate fits the Autotrol Performa 255 and 400 series control valves and is used when converting the valve from its original configuration to a single-spring setup. It sits over the top of the piston and seal stack, retaining the return spring assembly and sealing the top of the valve body. Supplied as the top plate only (no spring included), it's the part needed when carrying out a single-spring conversion or replacing a cracked or worn top plate during a valve rebuild, and is stocked by WrekinWater for servicing 255 and 400 series valves.

Technical specifications

Symptoms that mean you need this part

• The existing top plate is cracked, warped or has stripped screw bosses
• You're carrying out a single-spring conversion on an older double-spring 255 or 400 series valve
• The top plate is leaking or not sealing properly against the valve body during regeneration
• You're rebuilding the valve and the original top plate is missing or too worn to reuse

Why it fails / why it matters

The top plate closes off the top of the control valve body and locates the return spring that helps drive the piston back through its regeneration positions. Autotrol's 255 and 400 series valves were produced with different spring configurations over the years, and this top plate is the part used to standardise an older valve onto the current single-spring arrangement, which simplifies future servicing. Because the top plate takes repeated mechanical load from the spring every regeneration cycle, it can crack or the screw bosses can strip over time, at which point replacing it during a rebuild restores a proper seal and spring location.

Why buy this from WrekinWater

WrekinWater has supplied Autotrol, Fleck, Clack and Kinetico parts to installers and DIY customers for over 15 years from its Bettisfield, Shropshire base, and stocks conversion and service parts like this top plate for older 255 and 400 series valves that are still in widespread use. With more than 50,000 customers served and an Excellent Trustpilot rating, WrekinWater makes it straightforward to source the right part for a valve rebuild rather than replacing the whole unit.

How to fit it

1. Isolate the softener at the bypass valve and shut off the mains supply before starting work
2. Remove the control head or timer as needed to access the top of the valve body
3. Undo the retaining screws and lift off the old top plate, taking care as the spring may still be under tension
4. Fit your single spring into the valve body in the correct orientation
5. Fit the new top plate over the spring and secure with the retaining screws, checking the seal is seated correctly
6. Refit the control head or timer, restore power and mains supply, then run a manual regeneration to confirm correct operation