DIY Doctor UK DIY Forums

My system - I'm no expert on this, but basically we have a large cold water tank in the loft, with a smaller tank next to it for the central heating. Also have a hot water cylinder in the airing cupboard and a boiler downstairs. House was built in the 60's. I've had the central heating and boiler checked and they are both in good order.

The problem - We had a new shower installed a few months ago. After months of having a dripping overflow from the cold water tank, I've now found that this has been caused whenever the new shower was used. It was difficult to diagnose as there are a few of us living here, but the problem only occurs when the new shower is used.

[b]Basically whenever it is used, hot water enters the cold water tank from the hot water feed at the bottom of the tank[/b]. Even though the shower has only been on 15-20 minutes, the hot water continues to come into the tank for several hours, gradually diminishing in pressure. This causes the tank to overflow, and water to pour out the overflow pipe. The ball float in the cold water tank is definately not the problem. The new shower is located quite close to our boiler.

Our other shower upstairs works fine with no problem. I can only assume the new shower has not been connceted correctly. Is there any way this can be solved simply? I am reluctant to call the person who installed it since they did it wrong in the first place (at least I'm assuming they have).
Any advice would be great.

What type of shower has been fitted ?

mixer or electric ?

If this is a mixer shower then this could be the problem, fitting a non-return valve to the hot water pipe will solve the problem. With the cold water being at a greater pressure than the hot - the water could be going back into the hot water supply, back-filling the cylinder and tank in the loft. You sometimes get the same problem with mixer taps.

But mixer showers, should not be fitted directly to colds mains. It should be tank fed.

The reason mixer showers cannot be connected directly to the cold mains is - if the cold water supply was turned off you'd have hot water only flowing to the shower, and you could be scalded.

If you can provide more info on what type of shower is fitted, and where the water supplies come from i should be able to help more.