In facilities, in addition to limiting, the system activity sequence is also important to achieve energy efficiency. Nowadays, with the general use of VAV (variable volume) systems in commercial complexes, simultaneous heating and cooling and overheating of the primary air are often ignored. Applying boiler restrictions based on outside air temperature, for example when the temperature is above . degrees Celsius, is an effective way to prevent this situation.

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.

Modular boilers are small in size and capacity and are usually used to replace several small boilers instead of one large boiler. These modular boilers pass through standard ports and are portable through stairs and elevators. These devices can be arranged in different order to make the most of small places or embed other equipment in those places. These boilers can efficiently provide the required heating load.

Cast iron boilers are very useful because they can be collected in the basement and passed through smaller doors and gates. The most important drawback is that they are prone to leakage due to the connection of the parts by the washer when the washer becomes old or damaged by chemical reactions. Among the famous cast iron boilers in Iran, we can mention the boiler cast iron boiler and M.I. cast iron boiler made by Iran Pipe and Machine Building Company.

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.