Central Heating 3 Port Motorised Valve

[guitarboogie]

I've just recently replaced our old Honeywell motorised vale with the Drayton MA 1/679-3. Whilst switching between the three options works ok ...viz
1. CH only 2. HW only 3. CH plus HW .... the problem is that when CH is no longer called for at the end of a CH period, the motor remains energised holding the port B position closed against the tension of the auto return springs resulting in the motor overheating.
I have got round the problem somewhat by programming for a 10 minute HW cycle following each CH period in order to ensure that the motor releases and allows the return springs to the port A closed position.

I'd be grateful for any guidance on how to resolve this situation properly please.
Kind regards,
Tony Butler ([email protected] or phone [phone])