Just got up to make the tea and discovered (I think) that what I thought was the MV for the HW is in fact one for the heating. So I have opened the valve on the correct HW valve and am getting heat on the top side of the pipe. If I leave the valve open on this MV until I can get a new Syncron which will probably be after Christmas am I doing any damage to anything or would it be better to switch the immersion back on while we have got a house full of family here ? It's quite interesting that the levers on the 2 MVs for the heating have gone "sloppy" because they have opened but the one for the HW hadn't but when I opened that one up manually I soon got hot water on the top side of the pipe. All heating and HW come on at the same time in the morning at 6.00 am.