Running CH stops HW heating up - 3 port valve?

[munkjack]

I turned on the central heating on the programmer recently and it didn't seem to work initially but next time the HW programme came on the water didn't get heated but the CH came on! Is it that the 3 port valve is sticking? If so what can be done to fix it? It's a Siemens valve that's less than two years old.

 

[doitall]

Possibly, you can check it out with a multimeter.

You should have 240v on the orange in the HW mode.

240v on the white, orange in hw & htg.

240v on the orange, grey & white htg only.

 

[munkjack]

Thanks for that. Before I saw this reply I removed the actuator cover and that allowed the lever to move further over which means that the system will only produce HW now, no CH. I suspect that the actuator may have died already but will see if I can measure 240v at the places you recommend.

 

[munkjack]

I couldn't measure 240V at all the places you mention so replaced the programmer, CH still doesn't work. I now get 240v for the HW, CH & HW settings but not orange for CH alone. In this state the actuator makes a noise as if it's trying to move but nothing happens!

 

[seco services]

sounds like the spindle is seizing.

 

[munkjack]

Thanks for the suggestion but the valve is less than three years old and moves easily when you push the lever. Looking on the web a lot of people have had this problem with this piece of c*!p valve so I cut my losses and put in a boss, now all is well and I have a spare programmer.