Heating but no hot water

Hi Mike,
We have a Boilermate II and heating the radiators is fine but when hot tap turned on, water starts to come out hot but then turns tepid in a few seconds. Please help
thanks

Matthew

Hi;
Depending on the age and the usage it has had.
A descale may be required.
And whilst have that done a new mixer / blending valve.
What part of the UK are you.
There are people advertising on here ( Home page)
Or Google up for your area.
Mike
MGC/H2O
Norfolk

Thanks for reply,
We live near Chelmsford in Essex and have had the Boilermate II from new since Dec 1999. We have had a very good water softener fitted over four years ago so have not had hard water since then so a de scale not likely to be needed. Looking at other posts, can see info on the mixer valve so can see this may be the cause. Is this called the Brawa Mix Valve and does it have a thermostat on it or is just like turning a tap to open/close the valve letting more or less cold/hot water entering the hot water pipe. Am a little concerned with what seems the lack of qualified people that have come across these thermal store heating systems so do you know of any in our area? Also are these valves easy to get hold of and if so approx how much are they?

thanks
Matthew