The Basics of Boiler Systems

Topics: steam heating, condensing boilers, boiler systems, hydronic boilers, cast iron boiler, steel boiler

Michael Tobias
Author : Michael Tobias on October 16, 2018

Chicago is one of the largest cities in the United States. It is also known to have warm summers and colder winters. Furthermore, the temperatures can still go below 0° C especially in January, the coldest month of the year. With the increase in industrial developments and unpredictable weather in the city, it is imperative to have an efficient power source and heating in place.

This is where a boiler plant comes in. The boiler is generally a closed container where a fluid is heated. The basic design of a boiler can be used in different applications.  Other than being used for locomotives, it can be used in combustion engines and power plants as well.  It is also known as the steam generator of a fossil fuel power plant. The boiler is used to help the combustion of coal, natural gas, or oil. In nuclear plants, the boilers are heated by steam generators that are caused by nuclear fission, both of which are available in Chicago.


A boiler system is only a part of a hydronic system.  Though the there are different types and designs, a boiler has four main components. These are

  • Burner - It starts the combustion in the boiler. A thermostat is used to send an electronic command to it to produce the desired heat. It is often placed beside the fuel tank. The nozzle on the burner then spays the fuel and ignites it. As a result, it creates a reaction within the combustion chamber
  • Combustion Chamber - The fuel is burned within the combustion chamber. It is commonly made of cast iron. The temperature in the chamber can rise to over a hundred degrees. Furthermore, the heat that was generated from the combustion chamber will then move to the heat exchanger.
  • Heat Exchanger - The heat exchanger heats up the water without having direct contact with the fluid. It is much like how boiling a pot over fire works. After that, the pressurized water is pumped through the pipes to the baseboard radiators or heaters.
  • Plumbing System - The plumbing systems are used to supply and distribute the heat. The design and the material used on the pipes may vary depending on the type of boiler.

Heating can generally cost you twenty-five to thirty percent of your total energy cost for a commercial building in Chicago. Having a high-efficiency boiler can reduce it by ten to thirty percent.  If you have the wrong type of boiler, it can easily cost you more. So, it is important that you choose and install the appropriate boiler with the correct specifications to meet your building’s heating requirement. It is also best to have frequent preventive maintenance to keep your energy costs low. The maintenance can include removing debris and residue in the combustion chamber, replacing the gaskets or other components, and temperature testing, as well. Boiler systems should only be maintained and installed by licensed technicians. If they are not properly installed and maintained, fatal accidents can occur.  

Types of Boiler

Here are the types of boiler systems.

Steel Boiler – there are two types of steel boilers:

  • Fire-Tube Boiler

The combustion gases or hot gases of a fire-tube boiler passes through straight tubes while water surrounds it. As a result, the water surrounding the tubes gets heated up. In most cases, the water is then circulated or converted to steam.  These types of boilers are commonly used for marine service since it is more compact in size


  • Compact
  • Easy to clean
  • Easy replacement of tubes
  • Inexpensive
  • Best for commercial heating and industrial applications


  • Has limit to the capacity of steam it can generate
  • Cannot handle high pressure of 250 psig and above
  • Water-Tube Boiler

Water tube boilers are the exact opposite. The water passes through the tubes and valves while the combustion or the hot gases surround the tubes outside.  It is best for industrial applications rather than heating.


  • Has larger sizes available for higher steam generation
  • Can handle high pressure up to 5000 psig
  • Can reach high temperatures


  • Can be expensive

Cleaning can be quite difficult

Cast Iron Boiler

A cast iron boiler is made with three types of sectional boilers. These are one-piece, horizontal-sectional, and the vertical-sectional. These parts are then assembled using grommet type seals or push nipples. Plus, some can also be assembled with screw nipples and external headers.


  • One-piece is made of only a single casting pressure vessel
  • Horizontal- sectional are like pancakes that are stacked on top of another and are connected by push nipples.
  • Vertical-sectional, these are made up of sections that are standing vertically like how you would picture a loaf bread cut into sections.

Condensing Boiler

These type of boiler is usually used to provide heat or steam in a facility and industrial process needs, as well.  The water is added to the boiler to create steam. It is then distributed to points that need heat and build pressure. The steam then condensates. Note that the piping slope may vary depending on steam distribution needs.

Hydronic Boiler System

This boiler uses a loop piping system to heat the water. It is generally used for facility or water heating services.  It makes use of an expansion tank to heat and pressurize the water.  In some of the hot water systems, a compressed gas that is above the water level inside the water tank to maintain the pressure.


To define and secure the safety of facilities, professional organizations like the American Society of Mechanical Engineers or ASME regulate and develop policies and standards to be followed.  Historically, boilers were a cause of many fatal accidents or property destruction because of ineffective understanding of engineering principles.  It is crucial that the contractor you choose should follow the standards set by these organizations. To ensure your safety and the safety of your facility. In addition, they can help you identify points of improvement to increase the boiler's efficiency. It is also best to determine the capacity and capability of the boiler to identify the amount of load it can handle in the future.

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