Its a mystery

[Gosportcpl]

Hi can anyone suggest what to try.... if we switch CH on and turn thermostat up,open rads then rads heat up... then if we switch thermo down and CH to off, all is well...until the hot water comes on and the rads heat up as well. We have now turned all the rads off... very confused...

 

[sadanorakman]

Do you have a combi boiler?

In my limited experience, Combi boiler Diverter valves often stick or fail in one position, so when you call for hot water, the heated water flows through the radiators as well as (or instead of) the secondary heat exchanger which heats your domestic Hot Water... Just search on here for it.

If you have a traditional system boiler instead with a separate hot water storage tank, then similarly, an electric valve (two way or three way) in your plumbing diverts hot water from the boiler between either your radiator circuit or your hot water tank... this valve may have failed (Stuck), or the electrical supply to it.

regards

 

[Gosportcpl]

Its not a combi boiler, so how should I check the valve? is it the white box in the piccy?

 

[sadanorakman]

erm, what picky?

 

[ianmcd]

removed reply posted twice

 

[ianmcd]

You have a Y plan system and it is most likely the 3 port valve actuator motor that has seized either that or the valve has become faulty, it is the grey headed one in your pics with unishare written on it

 

[picasso]

Unvented clinder on a three port ?