It is cold in the house. When I finally noticed at about 8:00 PM I called our friendly plumber who immediately drove out to see us (it helps a great deal when you pay your bills on time; people tend to be more willing to help). After take the cowling off the heating and checking all sorts of things, the guy asks me if we have enough fuel in the tanks. Oops :-( Note to self: first thing tomorrow morning, oder 6000 litres of oil.