cold/hot problem

[stuartj]

Hello
Could anyone please shed light on how in a domestic property with a new unvented cylinder fitted with no pipe crossovers would occasionally run hot water from the cold taps, I know i could fit a non return valve on the cold feed but i was just wondering why this would happen.

Would be grateful of any help

Stuart

 

[Phil]

Its quite comman, hot & cold pipes are run together so the heat from the hot pipe heats up the cold .

Its worse in summer when all you want is a drink of cold water and you have to run the tap for a while before cold comes out.

 

[Bernie2]

Hmm! In Plumbing you are supposed to always run the hot pipe over the the top of the cold. That way the heat given off by the hot pipe doesn't warm the cold water or help make the cold pipe drip with condensation.

 

[REDSAW]

you may have mono taps and h &c are crossing over within the tap body.
put nrv on tap tails to mono tap and see if that solves it.

 

[stuartj]

Hello
Thank you for the replies, But what was actually happening was that the water coming from the cold was the same as the hot , I spoke to a plumber and he had only come across this once in a larger system and could not explain why it had happened.

The hot and cold are run from an external boiler house through a quad ecoflex along with a heat pump flow and return and the insulation does not permit heat transfer between the pipes.

It's a bit of a head scratcher

Stuart

 

[stevetheplumber]

Hello
Thank you for the replies, But what was actually happening was that the water coming from the cold was the same as the hot , I spoke to a plumber and he had only come across this once in a larger system and could not explain why it had happened.

The hot and cold are run from an external boiler house through a quad ecoflex along with a heat pump flow and return and the insulation does not permit heat transfer between the pipes.

It's a bit of a head scratcher

Stuart

stop scratching and see redsaws reply

 

[stuartj]

Hello
There are no mono block taps on the job,What it is that one boy has done the internal domestic plumbing and i have done the heating system and the cylinder and he has just hooked up to my hot/cold supply tails from my ecoflex which are linked from the boiler hse to a internal location and he assures me that his domestic arrangement has been fully checked,He reckons the hot is somehow being pulled down the cold of the ecoflex

Cheers
Stuart