New float valve and still overflowing

[Birtybasset]

Hi all,

One of the overflow pipes coming from the little copper tank above the hot water tank in the airing cupboard recently started dripping. No problem I thought, got a new rubber diaphragm washer thing and put that in the float valve. All tested and confirmed that it shut off the water at least a couple of inch below the first overflow. Next morning the overflow was dripping as the tank had filled up again and almost completely submerged the ball. Bugger. So I fitted a new float valve. Again fully tested and happy that it cut the incoming supply at the right level. Next morning same again, tank full and overflowing. Bugger.

Happy that the float valve was working properly I wondered if the water was coming in through the bottom outlet pipe. Luckily there is a ball valve before the float valve so I isolated the float valve, left it a few hours and sure enough the water level had risen and eventually started overflowing.

The problem I have is knowing exactly where that outlet goes to!

The rough layout of my water system is a Gas Boiler (Elan Ideal 2 NF230) in kitchen (ground floor), hot water tank in airing cupboard in bathroom (first floor) and small copper tank (the overflowing one) above tank also in airing cupboard.

Been doing lots of searching on here and the interwebz and apparently it may be down to a hole in the cylinder coil as suggested in the FAQ //www.diynot.com/wiki/plumbing:faq:faq18

I can put some pics up of pipes, etc if it would help?

Any help would be awesome!!![/url]

 

[moggridgeplumbing]

Did you check the ball is not full of water?

 

[Birtybasset]

yeah both the old float / ball and the new one do not fill with water.

 

[misterdubya]

Is the Domestic Tank higher than the header tank?

Mr. W.

 

[martyndc88]

is your expansion pipe letting the water in? do you have your CH / HW on overnight ?

 

[Birtybasset]

Is the Domestic Tank higher than the header tank?

Apologies but I don't know the difference!! Is the header tank the big insulated cylinder thing in the airing cupboard?!! All I know is that the only header / expansion tank I have is just above the hot water tank in the airing cupboard. No tanks in the loft or anywhere else.

is your expansion pipe letting the water in? do you have your CH / HW on overnight ?

Not sure. CH hasn't been on for at least a couple of months now.

 

[adlplumbing]

have you set vavle correctly and does it shut off if you lift it up
secondy is it the f and e tank
thirdly is water warm or hot

 

[moggridgeplumbing]

Perhaps a little pic would help

 

[Birtybasset]

have you set vavle correctly and does it shut off if you lift it up - Yes, tested with old one and new.
secondy is it the f and e tank - errr, how can I tell?
thirdly is water warm or hot - cold. Well, mostly. Just luke warm but I reckon only because it's in the airing cupboard with the hot water tank.

 

[Birtybasset]

Perhaps a little pic would help

On it like a car bonnet.... back in 5....

Thaks for your help chaps.

 

[adlplumbing]

does it shut off when you lift the ball vavle up

 

[moggridgeplumbing]

Is it a combined cold water tank and hot water cylinder?

Have you recently changed any taps in the house?
And are any of them mixer taps?

Answer could be mains backing up hot water pipe back into tank.

 

[martyndc88]

is your expansion pipe letting the water in? do you have your CH / HW on overnight ?

Not sure. CH hasn't been on for at least a couple of months now.[/quote]

perhaps its expanding into tank, after pic will be more clear

 

[Birtybasset]

It's overflowing from the white plastic pipe. The inlet is the second one from the top. Top one goes into top of hot water tank underneath.

 

[martyndc88]

Q the slagging off of pipework