Myson MPE 222 problem?

keystone

[STRIKE]I might be out of touch ('cos its at least a couple of years since I've touched an S plan system) but if the HW zone valve operates correctly (as does the CH zone valve) when both DHW and CH are selected together at the programmer and both stats are calling for heat then the actuator should be OK? In which case there is no reason for it not to work when DHW only is calling for heat unless its a wiring issue elsewhere. Mind you you've both suggested the same thing (albeit on different forums) so it could well be me out of step.[/STRIKE]

Light bulb moment!! Ignore me - I'm talking bollox and have been all afternoon on this one. This isn't an opening and closing the valve problem. Its a providing volts to the blasted boiler problem. Talk about not seeing the wood for the trees. Duh!

Cheers

unclebulgaria

Ive changed quite a few of these two port valves, they're not very reliable. They have a very bad habit of looking like they're working and going through the motions but not actuating as they operate. Its usually a dodgy switching. Its way to complicated to explain on here how to test them so if you know an electrician or a heating engineer who is very electrically savvy ask them to test its operation in the wiring centre. The new heads are readily available and are cheaper to by as a full valve with brass body than separate head. Two screws, one on each corner, hold the valve head in place and wiring is reversal of removal.