hot cold water inlet on combi boiler

[eddiebrown424]

Hi,

anyone any ideas, the DHW from the combi is only tepid yet the outlet from the boiler is hot. This led me to think that it was not the secondary heat exchanger so i reported that i think that the water is mixing and due to the cold pressure being greater this is forcing the hot water back up the cold feed to the boiler. i suggested non-return valves on the pipework to the taps. Is it possible or does anyone have another solution. The cold feed to the boiler is hot. The problem has only just started (possibly its a let property) after a new cartridge was fitted on a cubic shower mixer. I have heard that the hot and cold can mix is it possible?????

 

[AWheating]

on a combi the hot and cold is the same pressure as its the same.

get the landlord to send an engineer around to take a look.

 

[Centralheatking]

Awh was being kind - I think you are out of your depth - go get a professional CHK

 

[eddiebrown424]

Awh was being kind - I think you are out of your depth - go get a professional CHK

Cheers CHK I've been plumbing for a few years now although i have just done my gas and have ltd experience on diagnostics and am the first to acknowledge I don't know everything......

I thought on a combi the pressure in was the same but the flow rate on the dhw was less after it passed the heat exchanger so if the mixer taps are mixing prior to the outlet this can cause a temperature drop on the hot and a non-return valve would solve it.

 

[AWheating]

if the mixer mixes in the tap valve/spout then the customer has the choice to turn the tap operating handle to adjust the mix. Its not likey the cold will go down the hot when the tap spout offers a route of little resistance and the supply pressures are simular.the same.

remember that normally the water only mixes when the tap is operated and not while its closed.

if you had a tmv valve with unequal pressures then it may cause a problem.

 

[eddiebrown424]

if the mixer mixes in the tap valve/spout then the customer has the choice to turn the tap operating handle to adjust the mix. Its not likey the cold will go down the hot when the tap spout offers a route of little resistance and the supply pressures are simular.the same.

remember that normally the water only mixes when the tap is operated and not while its closed.

if you had a tmv valve with unequal pressures then it may cause a problem.

Thanks awheating