There are four popular types of house heaters: furnaces and boilers are popular in colder regions, and heaters with resistance heating and heat pumps are popular in warmer areas. Additionally, some homeowners use space heaters instead of central systems.
Furnaces and boilers typically burn a fossil fuel to generate heat, with natural gas being the most popular fuel source. Furnaces warm air and blow it through the home, while boilers heat water and send it to pipes and radiators. Boilers offer better efficiency, with hot water boilers providing better efficiency than steam boilers.
Many air conditioning units use electrical resistance to generate heat, which can then be blown through the home using the unit's fans. This process is inefficient, making it unpopular in regions that need regular heating. Heat pumps, which can both heat and cool a home, also use electricity but capture heat and move it inside or outside the house. Their efficiency wanes in colder regions.
In older or smaller homes, traditional options are sometimes sufficient. Fireplaces, perhaps the oldest in-home heating concepts, can warm a small space, and many homes still have fireplaces even if they are not the primary heating option. Space heaters are often used for rooms that central heating systems fail to warm sufficiently.