Hi

Last weekend the overflow to the expansion tank started to drip. I took a
look at the tank and manually reduced the water level in the tank. I was
expecting to find the ball-valve feed dripping and needing to be replaced -
but it wasn't.

Over the last few days the water level in the tank has risen around 1", so I
presume that water is returning via the expansion pipe. Could someone expand
on what the possible causes are?

Thanks