Leaking expansion tank

[cj.wheeler1]

Recently I have had a leak in my expansion tank as the water level has gone very high and I think it is leaking back out of the hole where the inlet pipe is when the water rises to a certain level. It appears to be a slow leak that gradually builds up.

The system has been like this for years so I don't know why this problem has started now. Could it be faulty ball valve?

I emptied out expansion tank on Sunday a let it refill and it was fine but a few days later it was leaking again>

Any suggestions?

Thanks

 

[twgas]

did ball valve shut off properly, I'd be inclined to change it anyway, only cost a few quid and a few minutes. set water level to just above outlet at bottom of tank. dont forget to turn water off !

 

[JohnD]

have you got any mixer taps. especially ceramic taps or showers, where the cold supply is at mains pressure?

How old is your hot-water cylinder?

Turn of the cold main supply to the house, make sure no-one turns any taps or flushes WC while you are working, then go and sit in the loft for a while and see:

Does the F&E stop overfilling, or continue?

If it continues, is the water level in the cold water storage tank (the big one) dropping by the same amount of water as is spilling from the F&E?

 

[cj.wheeler1]

Thanks - yes ball valve shut off OK so I think it is working OK

But based on what you said the water level is probably too high to start with - when i refilled it ball valve shut-off the water at about half full but based on what you say it should be much lower i.e just about bottom outlet which would allow for more expansion as the water heats up?

 

[cj.wheeler1]

Thanks John D

No all showers, taps (apart from kitchen) etc are from cold water tank rather than mains.

HW cylinder is about 4 years old.

Perhaps I should try your suggestion tomorrow

 

[JohnD]

Swap the ball-valve anyway - it's cheap and easy (the cylinder isn't)

See if you can put a jar or something under the ball-valve so you can detect any dripping.

 

[cj.wheeler1]

Had a closer look today and the ball valve was leaking slightly I think which explained why it was OK for a few days when I first drained and refilled before it started leaking again.

I discovered that it was actually leaking because the plastic nuts that hold the ball valve either side of the tank weren't fully tightened and this was slightly below the overflow.

Have fitted a new ball valve today so fingers crossed!

Thanks for all the suggestions.

 

[Softus]

I discovered that it was actually leaking because the plastic nuts that hold the ball valve either side of the tank weren't fully tightened and this was slightly below the overflow.

Have you left it like that?

 

[cj.wheeler1]

Softus,

I tightened up the plastic nuts and have overfilled to check it wasn't leaking - then drained it and allowed it to refill to normal level - so far so good!

 

[Softus]

That's good, but not what I meant.

The top of the warning pipe outlet should be below the bottom of the mounting hole for the float valve.

 

[cj.wheeler1]

I assume by "warning pipe outlet" you mean the overflow? This is roughly at the same height of the mounting hole for the float valve but possible the overflow is slighty higher.

 

[Softus]

I assume by "warning pipe outlet" you mean the overflow?

I do.

This is roughly at the same height of the mounting hole for the float valve but possible the overflow is slighty higher.

That's unwise, for the reason that you've recently discovered.

 

[cj.wheeler1]

Water level still appears to be rising, slowly but gradually - I checked it first thing this morning and it had risen slightly but all water in feed and expansion tank was cold so I don't think it is coming from the pipe which overhangs the top of the feed and expansion tank as I assume this would be hot? (and it was also dry to the touch)

The ball valve has been replaced and is not leaking so where is the water coming from???

Hot water cylinder is only about 4 1/2 years old so that should be ok.

 

[Softus]

The ball valve has been replaced and is not leaking...

Hot water cylinder is only about 4 1/2 years old so that should be ok.

One of these statements is as assumption.

Either your float valve is still leaking, or the cylinder is very much not OK.

 

[cj.wheeler1]

Well I am as certain as I can be that the float valve is not leaking having observed it for a long time.

Is there anyway I can test for the problem being with the hot water cylinder?

Is it usual for a cylinder to go wrong in less than 5 years?