I have been trawling the web on this issue with no success. My water softener (Autotrol 255 by the look of it) started to overfill the brine tank after some cold weather last winter. This is being caused by the air check valve (on the 255 valve body, not in the brine tank) being closed all the time. I can do manual regens by removing the float and catching it before any air get sucked in. I know the ball should float after the regen, but since the last step seems to be to flow hard water into the brine tank, how can this be. The ball will only float in soft water.