Basic Parts of a Boiler

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A boiler is a self-contained combustion system that heats water. The hot water or steam produced by a boiler is then used in heating systems. Although designs vary, a boiler has four main parts: the burner, the combustion chamber, the heat exchanger and the pluming apparatus.


The burner initiates the combustion reaction within the boiler. Thermostats send messages to the burner electronically when the system needs to produce heat. Fuel is pumped by a filter mechanism to the boiler from an outside source -- often an adjacent fuel tank. A nozzle on the burner turns this fuel into a fine spray and ignites it, creating the reaction in the combustion chamber.

Combustion Chamber

The fuel is burned in the boiler's combustion chamber, which is usually made of cast iron. Temperatures in the combustion chamber can rise to several hundred degrees, usually in a very short time. The heat generated in the combustion chamber is transferred to the system's heat exchanger

Heat Exchanger

In a hydronic boiler system, water is filtered around the combustion chamber through a series of flue passages. The pressurized, boiling water is then pumped through pipes to baseboard heaters or radiators, which give off the heat energy produced in the boiler.

Fuel Sources

Boilers can run on a number of fuels. Heating oil, kerosene and liquid propane are common.

Other Uses of the Design

The basic design of a boiler system is used for a variety of functions besides heating, including steam-powered locomotives, external combustion engines and power plants.


Annual maintenance and cleaning of boiler systems is necessary to keep the system at peak efficiency. This can include the removal of residue and debris from the combustion chamber, replacement of gaskets and other equipment and temperature testing.


Boiler systems should only be installed and maintained by trained, licensed technicians. Due to their intense heat energy, boilers can be extremely dangerous if not properly installed, operated or maintained.

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Maxwell Wallace

Maxwell Wallace has been a professional freelance copywriter since 1999. His work has appeared in numerous print and online publications. An avid surfer, Wallace enjoys writing about travel and outdoor activities throughout the world. He holds a Bachelor of Science in communication and journalism from Suffolk University, Boston.