The burner combines fuel and oxygen to create combustion conditions with the help of a combustion device. This combustion takes place in a combustion chamber and the heat generated is transferred to the heat exchanger water. The controls regulate the combustion process, the ignition rate of the burner, the required fuel, the amount of air required, the water temperature, the steam pressure and the pressure of the engine boilers.

Cast iron boilers that are cross-sectionally cast iron are another type of engine room boiler that is used to heat commercial premises. These boilers do not use pipes, but instead, have cast-iron sections with water and combustion gas corridors. The cast iron parts are screwed together and look like a steam radiator. These parts are connected to each other by fireproof washers. These boilers are used to produce steam or hot water and are available in sizes from , to , BTU.

Electric boilers are used in buildings that require very little steam or no access to natural gas. Electric boilers are referred to as clean, quiet, compact, and easy to install boilers. The lack of a combustion process reduces the complexity of design, execution, and maintenance. Heating agents can be easily replaced in case of failure. This type of engine room boiler can be used to generate steam or low pressure or high-pressure water or it can be a good option for those consumers who are limited by gas emission laws. Their size varies from , to , BTU input. In general, its efficiency is % to %.

Steel boilers, as their name implies, are made of steel and are usually made of horizontal cylinders. Steel boilers have a combustion chamber in which pipes are placed around this chamber. The pipes that are installed around the combustion chamber of steel boilers are made of a special alloy so that they do not burn or damage in the face of a direct flame. These pipes are called (fire pipes). Steel boilers are divided into friends from the point of view of heat transfer, which are as follows.

Ventilation gas savings provide the best heat recovery opportunity. In boiler chimneys, there is a need for heat exchangers to transfer heat from the flue gas to the return water or to feed the boiler or combustion air. They even work well in boilers and operate at relatively low flue gas temperatures. There is a large room to recover some of the flue gas heat, which rises if the flue is not recovered. Saving gas from the chimney usually increases the overall efficiency of the boiler by to percent.