Autotrol 255 Float ball for Air Check Assembly

The 255 float ball is the small buoyant sealing float fitted inside the air check assembly on Autotrol 255-series water softener control valves, sold by WrekinWater. It rises and falls with the brine level in the safety float housing, seating against the air check orifice to stop air being drawn into the valve when the brine tank runs low. Anyone servicing an Autotrol 255 softener that's drawing air, cycling erratically during brine draw, or failing to draw brine properly needs this part on the bench.

Technical specifications

Symptoms that mean you need this part

• The softener draws air during brine draw and regeneration becomes noisy or erratic
• The air check assembly won't seal once the brine tank runs low, letting air into the valve
• Salt usage climbs because brine draw is inconsistent from cycle to cycle
• The float ball is visibly cracked, waterlogged or no longer floats freely in the air check housing

Why it fails / why it matters

The air check assembly on an Autotrol 255 control valve exists purely to stop air being drawn into the valve body once the brine tank empties during the brine draw stage of regeneration. The float ball inside it is designed to float on the brine and rise to seal the orifice the moment the tank runs dry, protecting the injector and drive mechanism from air-locking. Over time the ball can crack, become waterlogged or lose its buoyancy from constant exposure to saturated brine, at which point it stops sealing reliably and the valve starts drawing air on every cycle, producing an erratic, spluttering brine draw and inconsistent regeneration.

Why buy this from WrekinWater

WrekinWater has been supplying genuine and genuine-spec Autotrol parts from its Bettisfield, Shropshire base for over 15 years, and stocks the full range of Pentair Fleck, Autotrol, Clack and Kinetico components so small internal parts like this float ball are always available rather than tied up in a full valve order. With more than 50,000 customers served and an Excellent rating on Trustpilot, it's a straightforward, low-cost fix to have on hand before a service call.

How to fit it

1. Isolate the softener at the bypass valve and disconnect the brine line from the control valve
2. Locate and open the air check assembly housing, usually a small screw-fit cap on the brine line connection
3. Remove the old float ball and inspect the housing and orifice seat for scale or debris, cleaning as needed
4. Fit the new 255 float ball into the housing, checking it moves freely and floats correctly in water
5. Reassemble the air check housing and reconnect the brine line
6. Restore the bypass to service position and run a manual regeneration to confirm brine draw is smooth and air-free