What are Boilers?

Sherry Holetzky

Boilers are systems designed for heating air or water to produce heat or energy. They can be incredibly simple or fairly elaborate, but basic models are made up of an enclosed container where heat is applied to water, which is then circulated throughout the system in the form of hot water or steam. The water must be boiled to create steam, giving the device its name.

Boilers heat water to produce warmth.
Boilers heat water to produce warmth.

Many home heating systems and water heaters that use boilers don’t actually boil the water, however. Instead, water is generally heated to temperatures somewhere roughly between 140° and 200°F (42.14° to 93.3°C), although some people lower the settings to save energy and money.

A radiator connected to a boiler.
A radiator connected to a boiler.

Much like a typical furnace heats air, boilers heat water or other heating fluids. The heated liquid then passes through pipes rather than ductwork to a particular heating implement, such as a radiator, to disburse heat. With radiant heating systems, sometimes referred to as heated floors, pipes can be placed in the floor or ceiling. The water is heated, and then moved through the pipes, which distribute heat throughout the space instead of at the end of a line via some other form of heating implement.

Some central heating systems use boilers to heat water or air that is then used for warming a home or building.
Some central heating systems use boilers to heat water or air that is then used for warming a home or building.

The air used by a furnace is re-circulated, being warmed and cooled again and again. The same is true of the water or fluid used in a boiler, although the methods and equipment used to heat the materials are different. Furnaces rely on fans while boilers rely on pumps. They must be connected to the plumbing system in a home or commercial property so that water can be provided to the heating system. Newer models may also include a safety feature that shuts them down if the water level is too low.

Some other features include pressure control valves to keep the pressure from building up too much as water is being heated. Many also have a larger tank that is used to hold the water as it expands during heating. While these appliances may be simple and effective to use, they must also be used safely, and many modern designs are equipped with many safety features.

Boilers also have the added benefit of not requiring air filters, so cleaning and replacing air filters is not necessary. They typically have features to keep the water within the system from returning to the water source.

Steam boilers are used for heat and energy.
Steam boilers are used for heat and energy.

You might also Like

Readers Also Love

Discussion Comments


I clearly remember the days of hot water boilers as a way to heat a house or building. When I was very small, we had heat registers against the wall. We kids, were reminded constantly not to get close to the heater registers.

Once in while, we would hear stories about water heating systems blowing up. Then, there weren't the safety features like valves to shut off if the water level became too low or if the pressure became too high.

In one of the old elementary schools I went to, we had a boiler heating system. Everyone knew where the boiler room was. We always made jokes about the "boiler man" and what he was doing in his little room!

Post your comments
Forgot password?