Bath mixer Tap

[SPACEY]

Hi
I have a problem which I think might be down to the bath mixer tap but i'm not sure. The symptoms are:
1. When the hot water tap is turned on the water comes out hot but at a
lower pressure than normal. If the cold water tap is turned on all hot
water flow stops. If the cold water tap is then turned off, cold water
continues to flow before eventually coming out hot again. It is as if the
cold water is finding a way across to hot side and flowing down the hot
pipe.
2. The water level in the hot water header tank rises while running a bath
and water comes out of the overflow.

The cold water is fed from the rising main, the hot water from a header tank/cylinder - 22mm pipe.
The mixer tap looks quite old and has an integral shower, there is a leaver to switch between taps and shower.
I hope somebody has some idea what the problem might be.

Thanks.[/list]

 

[Bahco]

You need to repipe the cold water, changing it from a mains pipe to a new outlet off the tank. Your supplies are not balanced and the cold water is overpowering the hot.