Overflowing expansion tank

[chriswatson73]

Have had a large damp patch on the outside wall (causing damp inside) for a couple of months and have just worked out where it was coming from ( after a false alarm when i found that the bathroom tap was also leaking down the pipe onto the wall).

Even though I have never seen it, the overflow pipe must be dripping and flowing back along itself onto to brickwork.

I went up to the loft and found that when the heating was on, the pipe rising from the hot water cylinder into the tank is making the water level rise above the float valve (this is not leaking by the way) and through into the overflow pipe.

Any thoughts on what to do?

Rgds
Chris

 

[spraggo]

You need to replace or repair the float valve.

spraggo

 

[chriswatson73]

forgive me, not sure I understand.

The float valve is not leaking and overflowing. hot water is coming up from the hot water cylinder (i can see it when i shine a torch on the water at the bottom of the f & e tank) and making the water level increase when the heating is on.

 

[spraggo]

forgive me, not sure I understand.

The float valve is not leaking and overflowing. hot water is coming up from the hot water cylinder (i can see it when i shine a torch on the water at the bottom of the f & e tank) and making the water level increase when the heating is on.

Sorry I should have explained in more detail. The point is that how did that much water get into the expansion tank other than the ball valve leaking or that the ball valve was not originally adjusted to fill the tank only about 1/3 full?. If the water has risen that high then the distance between the water level and hiegth of the expansion pipe (where it forms an inverted "U" bend to return into the tank), which should be 450mm, is reduced, which will cause pumping over. Try lowering the water level and see what happens.

Regards
spraggo.