Overflow Feeder Tank

17 Jan 2006
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United Kingdom
My cold water feed tank (gravity system) to my hot water cylinder is overflowing. I have changed the ballcock and it is working fine. There is no leakage from the hot water overflow (into the feeder tank). The only other pipe is the cold water feed to the hot water cylinder. Does anyone know what the problem could be? It is overflowing even when cold water supply switched off and heating off. Can water re-enter the feeder tank from the hot water cylinder? ANy help much appreciated/
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Do u have a small f/e tank that feeds water to the heating system that is higher than the large tank that feeds the hot water cylinder.
Sorry I should have said it only feeds the hot water. The heating is all electric storage heaters. Thansk for replying.
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The water level in the feeder tank is about inch and half below the overflow level with the ballcock closed.

It seems to be expanding a lot to fill the feeder tank that much and then is constant drip out of overflow pipe outside. It makes no sense to me!
when u set the new ballvalve u will need about 4" gap between the water level & the overflow to acept the expansion of water when the cylinder heats up at nigt time. If the cylinder is very tall u may need more than that.
Thanks Bab. I might have a problem in that I only have a 4 gallon feeder tank but I will have a go. Thanks for everyone's help.
Sorry forgot to ask, to set the ball cock (as it is already right at the bottom of the arm) should I bend the arm? I know people do it but wasn't sure if it is the right thing to do.
if u only have a 4 gallon f/e cistern then u need it changing to at least 20 gallon. does ya hot water never stop coming out of the taps.
If I run a bath then that uses up all the hot water (top immersion on only). I live in little flat so no room for a bigger cold water feed tank unless it goes up in the loft. I am not sure how big the hot water cylinder is but if I use the bottom immersion then there is more hot water than i need.
Its up to u what u do. if u can get enough room for the expansion of the water & u can live with that small tank its not gona be a problem. its not how it should be but its not dangerous .when u use the top immersion only then u wont get as much expansion as heating up all the cylinder. Now u know whats happening & why u can decide how to live with it.
Thanks Bab. Makes me wonder how all the other flats are coping without hitting the overflow. To be honest the whole flat, fairly new at 2 years old, is a botched job. All I woudl say is never buy a house/flat from Fairview Homes, it's been a disaster from day one with leaking roofs, wrongly wired lights, leaking toilet, dreadful customer service and an even worse management company!! Happy days!!

Thanks for all your help.
U got me wondering now. have u got high pressure hot water at the taps good mixer shower or is it electric. I cant believe its a standard installation 2 yr old that sub standard. What s it say on the cylinder.(name etc)
The hot water isnt that high pressure to be honest. For that reason I had an electric shower fitted.

It wouldn't surprise me if it's badly designed and installed. I have wooden double glazing (!) and the wooden support for the feeder tank has been cut right the way through for the overflow pipe thus making the front support totally useless.
If i were u I'd ring local buildig control & ask them to put in writing what the recomended minimum capacity is 4 a tank fed cylinder is. To confirm that is what u have is there a pipe out of the bottom off the small tank that goes to the bottom of the cylinder .Does the hot water come out of the top of the cylinder to the taps & there is no other pipes going into the cylinder anyewhere else.

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