shower temperature problems

[gareth_sutton]

Hi,

I've just moved to a new flat, which has the fame "issue" as my old flat... which is pointing me towards the fact they have some things in common, but don't know how to rectify, especially as I am renting so I cant go ripping out the bathroom, or go installing an electric power shower (which is what I would like to do!)

The facts are:
3rd floor flat.
Combi boiler (hot water on demand) Worcester (not sure model no)
Boiler is about 3M away from the bath, on the same level.
Bath/shower... hot&cold taps, pull the lever on top and water is directed to the shower head...


the problem:

The hot and cold water mixes perfectly for a bath. can get a perfect temperature...

When switching to shower head, its either 100% burning hot (boiler down to min tap temp), or 100% cold.

The real strange thing is, the hot water seems to be able to "push" up the cold water feed?? thus, when it gets scolding hot and turn off the hot tap, the hot water comes out of the cold tap for a while, then it graduly gets cold again. This is also proved buy the hand washbasin cold water getting hot when the shower is running and it gets scolding hot.

This happened in my last flat, and the only way to counter this was to run the hot tap on basin, and both on shower thus halving the hot water pressure... which is annoying and pretty much a waste of hot water?!?

I'd love to experiment with a pump on the cold water feed to the shower, assuming its pressure is far less than the hot and getting pushed back?

I've also tried turning up the hot water temp, with the assumption it would go through the boiler slower to get heated up more (thats my experience with elec power showers..), but it gets hotter... but still higher pressure.

Is there any way to reduce pressure (as a thought... maybe closing an isolator part way under the bath??)

not sure about cold water storage tank..... could bathroom be fed by tank, boiler by mains?

 

[TicklyT]

It wouldn't be the first time a bath has been left with a gravity cold feed after a combi has been fitted.

The kitchen cold tap should have a mains pressure feed - any chance of teeing the shower feed from that?

 

[jaikaiman]

You should NOT take bathroom fittings off the cold mains unless there is a non return valve in place. This is a water bylaw.
The reason is 'back syphonage' could contaminate the drinking water supply.
Bathroom fittings includes, taps, shower valves etc.

 

[Rico99]

You should NOT take bathroom fittings off the cold mains unless there is a non return valve in place. This is a water bylaw.
The reason is 'back syphonage' could contaminate the drinking water supply.
Bathroom fittings includes, taps, shower valves etc.

Stop talking rubbish, the distance from the tap spout to the water level creates an air gap that stops the syphonage, the only place non return valves are needed are on mixer taps where the water mixies in the body intead of the spout and on outside taps where a hose could be left in a pool of water.

Check your regs again

Rico