A filling key. I filled it and after bleeding the rads it has dropped a little. We got just under 1 bar which a lot more than we had. I think I will need to do it again just to get it up to 1 and then it should be fine. When it was fitted no one told us anything about it, not even about the timeclock. I sussed that out myself. The instuctions were not that helpful. The wife has been known to have heating on during the summer so I needed to sort it. Thanks for the offer of advice I may have to take you up on that.
