Boilers use Water while Furnaces use Air to Heat Homes. When the cold air hits and the familiar sound of the heating system isn't heard, it's time to have your heating system looked at and possibly replaced. A common issue that comes about is what kind of heating system do I have, a boiler or a furnaces and what is the difference? Well there is a big difference between the two, first is the efficiency and how the each equipment heats the home. Boilers use water or steam, while furnaces use air to heat the home. This is where the terms forced hot air or forced hot water come from, as the system will force heated water through base boards or radiators or heated air through duct work. Boilers traditionally are more energy efficient than furnaces due to the delivery of the heated source. There is a lower amount of energy loss from piping involved with a boiler than the duct work that is required for a furnace. The energy energy rating fo...