The four main types of home heating systems are forced air systems, radiant heating systems, steam radiators, and hot water radiators. Forced air systems use a furnace to heat air that is then circulated throughout the house by ductwork. Radiant heating systems use heated water or electrical elements to warm floors, walls, or ceilings. Steam radiators use steam to heat radiators that then transfer heat to the surrounding air, and hot water radiators use hot water to heat radiators in a similar way.