I have recently moved into a house with a central heating system that runs from oil or/and the multi fuel stove. The water gets hot and then circulates into the connect radiators but they aren't hot just warm and don't stay warm continually. Any advice get my log burner between 300-400 range but cant seem to keep the house warm. I have turned off the radiators in rooms we don't use, set the speed of the pumps to 1 setting. Any advice on this ?