Twice this week the frost protection feature on our boiler has kicked in, which has puzzled us. It took a while to work out what it was, partly because it's new for us – this boiler was new in spring and the old one didn't have it, but also because, being activated by water temperature in the tank, it bears no relation to the room temperature. Last week was much colder than this week but it never come on. Maybe the cold water takes a week or two to make its way down from the Mendip aquifers, but you'd think then it would warm up as it enters the reservoirs.