Two radiators on when Heating OFF but Hot Water ON???

[Frizzy100]

We have a baxi boiler and both Hot Water and CH controlled by Lifestyle LP522. If HW on and CH off, two radiators upstairs (next to the airing cupboard) come on. If we then put the CH on (with HW on) the remaining radiators come on.

If we turn off the HW and then put on the CH, all radiators come on.

Is this a problem with the programmer?

Why do only two radiators come on when the HW comes on but the CH is off??

Thanks

 

[ratonnastick]

could be three port letting water through when its meant to be closed,(replace valve).or at sometime the rads were part of a towel rad set up,(change the pipework)or its been installed incorrectly.

 

[Frizzy100]

could be three port letting water through when its meant to be closed,(replace valve).or at sometime the rads were part of a towel rad set up,(change the pipework)or its been installed incorrectly.

Thanks - o.k where do I find the "three port" in order to replace valve? The house is only 3 years old so I know that it was not part of a towel rad set up. Until turning the heating back on after the summer, all was working well so I don't think it has been installed incorrectly.