The answer to 'what is boiler' is a central heating system that uses hot water or steam to heat a home or building. Boilers work by burning fuel, such as natural gas, propane, or oil, to heat water that is then circulated through pipes to radiators or other heating elements throughout the building. This heated water or steam then radiates heat into the living space, warming the environment.
Boilers are a common and efficient way to heat homes, especially in colder climates. They are often more energy-efficient than other heating systems, such as furnaces, and can provide consistent, even heating throughout a building. Boilers can also be used to provide hot water for domestic use, in addition to space heating.