Understanding How a Boiler Works

A boiler system actually consists of several separate parts that all work together to produce the steam or hot water needed to heat houses and many other structures. Besides the actual boiler which is the container that holds the water, there must also be a source of heat. Typically, this is some form of burner that creates heat from the combustion of a fuel. The fuel might be natural gas piped into the burner, oil that is stored in a tank nearby or a wood pellet burner.

Once the burners are lit and the heat begins to generate, the heat is applied directly to the boiler in order to heat the water inside to the desired temperature. Depending on the type of boiler being used, the heating process occurs in one of two different ways. The most common style of boiler is known as a Firetube boiler because of the way the heat from the burner is applied to the water boiler. With this type of boiler, the heat produced by the burner in the form of hot gasses is routed through a series of tubes that run inside the boiler itself. These tubes are set in banks that help  spread the heat throughout the boiler. They  are arranged to route these hot gasses through the boiler a total of four times for maximum efficiency before going up the flue. The typical Firetube boiler can produce up to 25,000 lbs of steam or 750 hp per hour at full steam. Some 80% of all boilers in use today are made this way.

The other type of boiler is known as a Watertube boiler in which  tubes of water are place in such a way as to let the heat from the burner hit the outer surfaces of the pipes directly and raise the temperature of the water. These tubes are arranged vertically inside the shell of the boiler and the system is built using two or three cylinders, with the top being the one that releases the hot water or steam and the bottom being used to collect the sludge that is created from heating water into steam. This type of boiler is used in an environment  that requires more than 750 hp of steam per hour.

With this boiler, the heat from the burner raises the temperature of the water inside the tubes to 212° F, at which point, it become steam that can be pumped throughout the home or building where it’s used as heat. Because this type of boiler can produce more heat and steam than is needed, you need to keep a close eye on the system and make sure that the automatic pressure relief valve keeps the pressure at a safe level. It’s important to get frequent routine maintenance inspections to keep them operating safely and keep your home warm for years to come.