Central heating actuator getting hot and not de-energising

I have recently had a Tower actuator installed (with new valve also) and ended up having to finish the job myself!! The concern I have is that mains power is removed and switched back on, the actuator sits in its de-energised position and remains cold (as I would expect). When either heating/water/both switch on, actuator activates. All good. However, when both switch off, I would expect the actuator to return to a de-energised state. It doesn't but instead appears to hold its final position and the body gets hot and stays hot. Remove the power and it returns to de-energised state.

It replaced an old Switchmaster motorised valve and I am not sure this is an appropriate replacement. I have a Switchmaster 900 timer (clockwork!).

Should the actuator de-energise when water/heating off and so return to an 'off' state? If not why does it get so hot?

Any help appreciated!!

Thanks

Quite normal operation for that type of mid-position type valve.

no it won't unless hw was the last call for heat.
if heating was the last call for heat it will stay in the energised position until hw called for
and yes it will be warm.

Thanks guys, puts me a little more at ease!!

Just to be really clear - even when heating and hot water are both off and system is cold, actuator will still remain hot if anything other than hot water was last call?

Cheers again!

thats correct

Excellent - thank you very much for v helpful and prompt reply - v grateful