Cold water mixing with hot

[danny12w]

Hi all,

Read a lot of articles on here & they have been very helpful!

I have a problem though which I would be very grateful if anyone has any ideas what it could be :

I have a combi-boiler & two mixer showers. One is a Bristan & the other is Altima? I cannot get any hot water from any of the taps in the house - it is just lukewarm. However there is a demand for hot water from the boiler and feeling the hot water exit pipe from the boiler it then goes burning hot. So I believe the boiler is working just fine.

Before the cold water supply goes to the showers there is a 3bar pressure reduction valve. I have taken this valve off and capped the ends so there is no cold water going to the showers. Immediately everywhere in the house gets hot water when required.

So am I right in presuming that somewhere in the shower system the cold water is mixing with the hot water & being pushed back through the entire system in the house?

Can someone suggest what might be the problem and what I should check/replace next?

Thanks in advance


Desperate Dan

 

[ecowarm]

Yes you are correct, fit non return valves to showers and will be fine.
Welcome to the forum by the way

 

[danny12w]

Thanks for the welcome & advice!

So there wouldnt be a problem with the pressure reducing valve? would the showers have had NRVs on them and they have just failed?

 

[ecowarm]

The PRV is it connected to hot and cold? some old ones for multipoint water heaters ballanced the hot and cold so it could be faulty if that type.
Some showers have NRV fitted some not. I would fit aditional ones, job sorted.

 

[danny12w]

The PRV is connected to just the cold water.

Tried taking the shower off but without smashing all the tiles not going to work!!

Will put a NRV about 2m from the shower mixer - will this work?

 

[ecowarm]

Yes as long as no other connections between. One on hot and one on cold.

 

[marleyco]

Something completely different to throw in the mix, had similar problem few years back, I found someone had connected a cold fill washing machine on a y piece at back of washer and put both hot and cold hoses to It. If you haven't fitted one recently then.... back to tIf showers, could also be the boiler. Although if showers both off then I can't really see how they would be mixing resulting in no hot water at taps

 

[danny12w]

ok just a quick update - fitted a NRV on the hot water line going into the shower. Result is that I have hot water everywhere in the house now - however the shower now seems to be not mixing! Suppose I could try a new thermostatic cartridge!