The answer to 'what does boiler do' is that a 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 baseboard heaters throughout the building. This hot water or steam provides the heat that warms the air in the living spaces.
Boilers are a common type of central heating system, particularly in older homes and buildings. They are known for their efficiency, reliability, and ability to provide consistent, even heating throughout a structure. Boilers can also be used to provide hot water for domestic use, in addition to heating the home.