Motorised valve running hot?

[mezzosoprano]

I've learnt an awful lot about motorised valves this morning from this forum, but am still a little confused about what happens when the hot water and central heating turn off! My valve sits above my central heating pump at a T junction in the pipe, so I presume it's a three way job. The CH and HW are working fine, but a few nights back I heard a hum from the valve at 4.30am (don't ask) and touched it to discover it was hot when all pipes were cold and CH and HW off. Since then, I've been keeping an eye (or hand) on it, and sometimes it's cold when all is off, but more often quite hot. I cannot work out whether it goes cold if the HW switches off first or if the CH does.

Basically I'm asking - should this valve be cool when the HW and CH are both off, or is the heat generated by the valve motors doing their normal thing? Your help much appreciated!

 

[D_Hailsham]

The valve can get warm, even when heating and hot water are turned off. It's all due to the way the valve works.

The "rest" position is with the HW (B) port open. The motor moves it to mid position (A and B open) or to CH (A) port only. The design of the valve means that, if the valve is in the CH only position and CH goes off, the valve will be held in the CH position by the motor.

It's nothing to worry about - unless it keeps waking you up in the middle of the night.

If you have a well insulated hot water cylinder it might be worth setting the hot water to run after you have showered/bathed and the heating has gone off. This heats up the cylinder for next morning and resets the valve to the rest position.