overflowing F & E

[Rik]

I've got a customer who's F & E tank keeps overflowing randomly and was wondering if anyone here had any ideas. I originally went and replaced the ball valve, it wasn't passing when I went but was old/scaled so I assumed that it was the cause and replaced it. Got a call yesterday saying it had started again so went back to take a look, again valve wasn't passing but water level in tank was high and it was overflowing. I took a look in the cold water storage tank which was well below overflow level and gave the valve a push, this caused the valve in the F & E tank to pass water ( which I can't think of an explanation for) so decided valve must be faulty, replaced it and checked it wasn't doing the same thing still. I then set the level of water in the F & E tank well below overflow level as I thought it was a bit high and the water expansion may have been contributing. This evening I got a message saying it had started again and was worse than ever, I've yet to go take a look but I'm wondering if it could be a small hole in the cylinder coil causing the water in the tanks trying to level out (cold storage is at higher level than F & E) I don't see how it can be anything to do with the valve now and I can't think of any other explanation.

So my question is can anyone offer any other explanations, and if not is there any easy way I could prove this or not?

 

[SimonJohns]

Coil has split

 

[Rik]

water in F & E has never been warm when I've been there so I don't think it's been coming over from the vent for some reason,

 

[Rik]

That's what I'm assuming, think it can only be the tiniest of splits. Was tempted to see if I could easily pressure test the coil somehow, just wanted to know if anyone had any easy trick to prove it or not.

 

[Gray0689]

Coil has split

Deffo sounds like it

 

[sonray ltd]

You say it only happens randomly, i take it when the heating/hw is on ?

 

[sonray ltd]

just wanted to know if anyone had any easy trick to prove it or not.

Isolate the cws from filling the cylinder

 

[Rik]

I'm not sure how random it actually is, just what I'm told. Whenever if been there it's been dripping. I'm convinced it's the coil but knowing what there like I need to be able to prove it in a way they can explain. I spent ages balancing the system (it's a bungalow with one drop that feeds all the pipework buried in the floors) after replacing some old rads for nicer looking new ones only to have to come back the next day as radiators weren't heating due to them messing with all the valves after i'd left and explained they shouldn't need to alter them. I must have been asked about 10 times does it not just need bleeding.

 

[Rik]

Isolate the cws from filling the cylinder

of course don't know why I didn't think of that. Thank you very much.

 

[sonray ltd]

. Whenever if been there it's been dripping.

Whats been dripping vent or ball valve ?

 

[Rik]

I meant the overflow

 

[sonray ltd]

If it's never been hot/warm in the f/e limits pumping over.
So looks like a poss faulty coil.
But need to see it happening yourself.

 

[Reg Man]

If the cold water cistern and Header cistern are at differnet heights and the coil in the hot water vessel is holed, then it is certain that the water will leak into the heating system and cause overflow through the header cistern