Hot Water runs cold/warm when CH is on

[whoami]

Hi,

I have a combi boiler that gives us piping hot water when set to hot water only. However, now we have started to use the Central Heating we have noticed the hot water only gets slightly warm. The boiler is set to 'Hot Water and Heating' and the CH is left on for long periods. I should say the central heating it working well and pumping out the heat. But it seems the only way to get hot water again is to switch the boiler back to 'hot water' only and then when your done switch it back to 'hot water and heating'...not great!

I should say the boiler was serviced recently and had a new heat exchanger put in.

Any ideas as to what is causing it?

Thanks mark

 

[Timmyturtle]

Dont know much about combis but sounds like a diverter valve not working properly

Please correct me if Im wrong

Boiler make/model may be useful ?

 

[gasmick2]

The problem is without knowing what make of boiler it is its dificult to diognose as different boilers use different ways for the water and heating control IE some have a bythermic heat exchanger, and other use a diverter valve, which can be a mechanical type working on water pressures, and some boilers use a motorised diverter valve , some even use 2 pumps 1 for heating 1 for water, and most have some sort of plate heat exchanger well modern boilers do ,, older ones use a type of exchanger with a coil inside a small vesel

but it sounds like a diverter for now