Leaking Shower Head

[jumpingjackflash]

Hi all. I need some advice as im installing a new bath and thermosatic shower which has had new pipework to it. The bath works fine, no leaks etc but the shower leaks from the head when the toilet is flushed or taps are run. Its as though there is some sort of syphoning effect going on. Its not a drip either, you could almost have a shower under the leak its that bad. Talked to my old man about it and he says I may need a non return valve putting in the pipework? Is this true? Also does the pressure of the hot and cold have to be the same as my cold supply is alot higher pressure. HEEEEEEEEEELLLLLLPPP.
Chris

 

[Softus]

Also does the pressure of the hot and cold have to be the same as my cold supply is alot higher pressure.

So, you have unbalanced supplies to the shower valve.

Who installed the shower? Why did they run unbalanced supplies to it?

 

[jumpingjackflash]

I run the hot and cold supplies to the mixer. Obviousley the cold is alot higher pressure. Can I compensate for this with my isolating valves.

 

[Softus]

I run the hot and cold supplies to the mixer.

Well unless the shower valve is a venturi type, then you should have balanced the supplies.

Obviousley the cold is alot higher pressure.

Obviously it shouldn't be. The manufacturer's instructions should tell you that.

Can I compensate for this with my isolating valves.

No. You need to fit either a pressure limiting device (for a crude solution), or a pressure balancing valve.