Help with Worcester Highflow 3.5

[jonspope]

Hello all,

My brother has the above combi boiler, he needs help (he certainly does!)

The heating and the hot water are always on if the boiler is fired up and connot be switched on independently. This has been goin on for ages and the only was to soleve it in the summer is to turn the rads off individually.

I have only got experience of conventional indirect systems but think it must be some sort of bypass valve in need of replacement. What do you think? & if this IS the problem what waould eb the cost of putting it right.

ALSO, whent he above is fixed, he would like to put some TRVs on the upstairs rads:

Is this possible with a combi?
Is there a limit to haow many rooms can have the TRVs fitted?
I have fitted these to a conventional system by creating a vacume in the pipes (thanks to forum help), how is this done on a combi system?
Cna this be done DIY or does he need a proffessional?

Many thanks

jon

 

[heatingman]

is it the the old 35 with twin pumps

 

[jonspope]

not sure, all i know is that it is called the 3.5 and it was installed in 1995.

 

[heatingman]

The old 350 had two pumps, 1 for hot water & 1 for heating, the bottom of the pump housing has a stupid rubber flap that is supposed to work as a non return valve, i expect the 35cd is the same as it also has 2 pumps. Hopefully someone with a definate answer will reply

 

[weargas]

sounds very much like the diverter valve stucked in mid position.