Ball Cock Disaster

[sharvey66]

I rencently fitted a power shower. Realising I needed a lot more cold water than I had in my header tank, I fitted a supplimentary cold tank to feed the pump above the hot tank in may airing cupboard.

Although every thing is actually working fine, I cannot stop the tank from overflowing. I have fitted 3 ball cocks of various different types and manufacturers all to no avail. I noticed that when the tank fills up and then goes into over flow the ball cock assembly distorts the sides of the plastic tank and so remedied this with a brass and wood assembly external to the tank. The valve now remains horizontal through out. The valve however still leaks. Well I say it leaks, there is no visable signs of a drip but it still takes less than 12 hours to overflow the tank, I am estimating this to be about 5-7 gallons at least, I have even tried to reduce the water presure by turning the external shut off valve from the mains by 45 degress or 50%. Just for good measure I fitted a bigger ball (Which does not have a hole in it!!! Not that the old one did either). I have tried bending the arm to shut off the valve earlier as well.

I have been told that these things do suffer from the tiniest specs of debris so have been very carefull not to get any crap in the valve and where there is a rubber membrain have been carefull not to over tighten and avoid pin holes in the rubber.

I am not a plumber, hence the post, but I am sure this is not rocket science. Although, using a little maths...I have stood and watched the valve with a dry try beneath for at least 10 minutes and seen no drips. If I take a drip and multiply it by 11 minutes and then by 12 hours it does not come to 5-7 gallons of water.

Unless any one has any theories I am going to assume for now that the only other possibility is that warm water from the tank is being drawn back up through the shower mixer into the cold tank. But even my limited understanding of physics tells me this is more like science fiction fact.

Please help

Desparate!!!!!!

 

[Nige F]

Ist rule ....ye cannae change the laws of physics.....Jim 2nd. rule Water finds it`s own level.....so if there is any stored water above your new tank could be the coil in the hot water cylinder leaking for instance

 

[sharvey66]

Actually this is a very good point and perhaps my reference to science fiction was a bit previous.

The header tanks for the cold supply that supplies the hot tank( and consquently the pump) is above the cold tank used to supply the cold to the pump. So I guess the pressure of the hot water is greater than the cold and you are right, even if the cold and hot are isolated by being on 2 different circuits through the pump, they meet at the mixer. If I were to shut off the water to the lower cold tank and leave it, I could see if the water in the hot tank driven by the higher mounted orginal cold tank was being forced into the lower tank through the shower mixer.

The question is then how watertight is the shower mixer, I am guessing that even with the shower off and no water flow out of the head, there is still a chance the mixer chamber is still open to both supplies hence the possibility that the origin of my overflowing water is the hot supply from the tank. It always bothered me that the cold tank water was a little warm but I just put this down to the fact its in the airing cupboard right above (12") hot tank. The overflow takes 12 hours with no shower use so it is possible the water has time to heat up from residual heat from the cupboard temperature, the other possibility of course its hot water finding its way through the shower mixer from the hot tank.

Might me gettinh there what do you think.

BTW thanks from the quick response, if I don't fix this its no shower or divorce or worse!!!!

What do you think?

 

[stem]

I think the clue may be in your expression "fitted a supplementary tank" is this supplementary tank connected to the existing one? and if so, is the water level in the original tank on a level with, or above the overflow of the new one?

If so there's your answer. One tank is filling the other.

Ah you figured it yourself, my typing is too slow

 

[sharvey66]

Thanks for the reply, Its beginging to look exactly as you suggested. the point where the water from both tanks meet is the mixer valve. Is it possible that the mixer although usefull for cutting of supply to the show head, does not isolate the hot and cold suplied from each other, and as they are obviously at different pressures, as the heads are different, water is leaking back from the hot supply to the cold. In effect the higher header tank is draing into the lower header tank?

 

[sharvey66]

So to remedy this I think I will put a non return valve of some description in the cold water supply to the shower mixer....any thoughts.

BTW many thanks for the replies....looks like one marrage/neck saved