Figure shows the combustion efficiency chart for natural gas fuel with electricity, which shows the relationship between excess air and flue gas temperature with combustion efficiency. For example, by following the Step line in the diagram, the amount of oxygen at % in the flue gas (as shown in the diagram equals approximately % of the excess air) and ° F as the flue gas temperature rises, the corresponding combustion efficiency is about . % is observed. At the same increase in the flue gas temperature by degrees Fahrenheit, the Step line shows that reducing the oxygen in the flue gas to % increases the combustion efficiency to about .%. The lower the percentage of oxygen in the flue gas, the less heat is transferred to the excess oxygen, resulting in increased fuel efficiency. The higher the efficiency, the more heat will be transferred to the inlet water instead of to the flue gas, thus reducing the flue gas temperature.

In commercial complexes, the boiler is very different in summer and winter, night and day, working days and weekends. Using a boiler can not apply this load difference well. When the heat generated by the boiler at the lowest ignition rate exceeds the heat required by the building, the boiler cycle will be interrupted. Starting and interrupting the cycle in the boiler is not efficient at all because, in each cycle, a pre-combustion discharge and a post-combustion discharge are performed to direct the heat out of the boiler. Also in the case of boilers that do not perform the adjustment operation, when the combustion efficiency is at its best, the cycle process does not allow the boiler to operate in the second boiler and the ignition rate is constant.

This type of pot or boiler is made up of connecting cast iron pieces called fins. Due to the ability to assemble and disassemble the cast iron boiler, it can be used in spaces where it is not possible to use a steel and integrated boiler. In fact, cast iron boilers are assembled and installed in the engine room. types of sections are used in the construction of each capacity of cast iron boilers, which are as follows.

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.

If a building has multiple boilers, you may be able to use the boilers in sequence to prevent repeated cycles. If you use boilers that do not adjust, it is better to use the next boiler when the capacity of one boiler is full, instead of disconnecting and connecting several boilers that are loaded. On the other hand, in regulating boilers, the efficiency of the boiler increases in the load-sharing situation. Therefore, using several boilers at the same time in load sharing mode is more beneficial than using one boiler with % efficiency. Figure shows the relationship between ignition rate and efficiency in boilers with adjustable air and fuel flow utilization.