Morning All. I have a 2m X 6m UPVC conservatory with warmup under tile heating. Although this warms the floor well and takes the cold edge out of the room it isn't warm enough to keep the conservatory doors open into the house so it isn't getting much use during the winter. I would like to use a free standing heater on a timer so I can set it up to run at the same time as the central heating so the room is still part of the house (if you know what I mean). So I really would like to know which type of heater would be the cheapest to run. I have been leaning toward oil filled but I may be wrong am I ?