Hot water problem

[ricfrench]

We have a bungalow with the hot water cylinder in a cupboard under the stairs(ok, I know I said bungalow, there is one bedroom upstairs). The hot water supply to the kitchen and ensuite is routed up, into the loft space and back down to taps and showers and works ok, it's no power shower but it works. The main bathroom however is different, it was added on later, the pipes are routed under the floors, the sink works fine but the bath/handheld shower has the problem I noticed the other day. We have tried it before but gave up, my wife had another go on Tuesday and I noticed the hot tank header overflowing, through the tap(mixer) and shower the water was fluctuating from red hot to freezing cold, it wasn't mixing at all.
Any ideas what could be causing it

 

[dcawkwell]

The bath has mains cold and vented hot water to the tap.
The mains cold is rushing through the tap into the hot tank and overflowing.

Solution is either supply the bath with pipe from the cold storage tank.
Or fix the whole house and replace the hot water tank with an unvented cylinder and have mains pressure hot water throughout the house.

Sorted.

 

[ricfrench]

I'd love to go unvented but cost and space for a massive tank are prohibitive at the moment, would sticking a non return valve on the hot do anything? Or would it knock down any remaining pressure we have?

Is fitting an unvented cylinder within the realms of a DIYer

 

[kvsalamander]

could pump the hot??

 

[dcawkwell]

I'd love to go unvented but cost and space for a massive tank are prohibitive at the moment, would sticking a non return valve on the hot do anything? Or would it knock down any remaining pressure we have?

Is fitting an unvented cylinder within the realms of a DIYer

Unvented tank would simply replace your existing hot water tank.

 

[HERTS P&D]

Check valve on the hot water supply to the tap. Job done.

Andy