The first, and perhaps the oldest, is the steam heating system. As mentioned by Home Advisor, many of the older and historic homes across the U.S. are outfitted with this system as they are durable, provide clean and dust-free heat, and include few moving parts. The basic function of a steam heating system starts with steam created by a boiler furnace through an oil or gas burner. As the steam circulates the pipes into radiators or other convectors, the heat from the steam is dispersed into the room. The water from the steam remains trapped within the pipes, cools down, and is circulated back to the boiler to cycle the heat all over again. As simple as this system may be, the major downside of a steam system is its inefficiency to evenly sustain warmth in a room or home, and it does require yearly maintenance to prevent leakages, blocks, and adjustment of the burner.