Commercial Construction Considerations: HVAC Systems - Part 2

In the last article, we took our first look at heating, ventilation and air conditioning (HVAC) systems in commercial buildings. The article focused on the air side of the process and discussed air handlers, roof top units, exhaust fans and ventilation. We also look at the hazards associated with natural gas or propane connections, the weight of the equipment and the greatest danger the movement of the toxic products of combustion throughout a commercial structure. We learned that many air handlers use water as a heating and cooling medium.

In this article, we are going to learn about boilers, chillers, and cooling towers. These are the water related pieces of equipment that firefighters will most often deal with and I feel that boilers pose the greatest danger to firefighters.

Boilers exist in many different applications and for this article we will look at boilers used for heating commercial facilities. Boilers are also used extensively in industrial facilities for many processes, these boilers can be very specialized and are outside the scope of this article.

Boilers exist in commercial facilities to provide hot water for both heating and domestic hot water. There are a number of different types of boilers including atmospheric, condensing, cast iron, water tube and fire tube. The type of boiler is relatively unimportant to fireground operations because they all perform the same process in a different way. They use a fuel to produce heat, this heat is then transferred to the water that is moving through the boiler. The hot water is then pumped to the air handlers where it transfers its heat to the air.

In many older facilities and in many campus facilities the boiler is used to change the water to steam. Then the steam is distributed throughout the building to the air handlers of over an entire campus. This all sounds pretty simple right? So why are boilers dangerous?

The two greatest dangers concerning boilers are the hot water or steam they produce and that combustion, the very process we as firefighters are trying to prevent, takes place within them. Boilers produce hot water that can range in temperature from 100 to 212 degrees Fahrenheit, as well as steam. At temperatures above 130 degrees F your skin starts to burn. It is important to know what you are looking at and what you are doing if you are ever been in a boiler room in any facility. Boilers are pressure vessels and opening or closing a valve that you know nothing about could result in a catastrophic failure of the boiler. Once again we come to the common theme of most of these articles, know the facilities you operate in.

The dangers of the hot water and steam exist throughout all buildings and not just in the boiler room. The piping that transports the hot water or steam is often hidden above ceilings and behind walls. Most of these pipes will have insulation on them and these insulated pipes pose little danger to firefighters. Non-insulated pipes pose a high danger of burns when touched. Additionally firefighters should not try to open or close valves that are part of the hot water or steam system. Opening or closing valves could potentially cause pipe failure, which could potentially cause harm to anyone working in the vicinity.

There are several items that are of concern on the combustion side of the boiler. Boilers use some type of fuel; this could be fuel oil, natural gas, propane, wood, or waste oil. It is important to know what type of fuel you are dealing with and we should be knowledgeable of possible fire dangers when they are in a confined space, particularly natural gas and propane. The fuel goes through a nozzle which disperses the fuel into fine droplets creating more surface area which requires less heat to begin combustion. This is important because the intensity of the fire at this point will be very great and can cause serious harm if the boiler fails or the combustion chamber is opened by someone who doesn't know what they are doing.

Chillers are a piece of equipment firefighters will not deal with often. Chillers use a refrigerant in conjunction with water from a cooling tower to make chilled water that is distributed throughout the building for air conditioning purposes. The most dangerous component of the equipment firefighters is the refrigerant. Some of those used today can cause asphyxiation, and other health issues. It is important that you know what is in use in the facilities you respond to.

Cooling Towers
Cooling towers are large metal structures that you will typically find on the roofs of buildings. Cooling towers reject heat from water used in chillers to the ambient air. The biggest danger they pose is the weight added to the building structure and the potential for injuring firefighters in the event of a collapse. It should also be noted that chillers are often located on roofs or in mechanical penthouses on the upper floors of a building. Again you need to remember this when operating in spaces below this equipment.

There are many pieces of HVAC equipment that you need to be aware of. As I have stated in the past you must know the specific problems that affect you by visiting the facilities in your response area. Please take some time to visit the structures and research how they are built and the problems the construction methods may create.

MATTHEW STIENE, a Contributing Editor, is a project manger for the Mecklenburg County Real Estate Services Department, and a firefighter with Robinson Volunteer Fire and Rescue, in Charlotte, NC. He is a licensed professional engineer in North Carolina, New York and Pennsylvania, and is a certified facility management professional. To read Matthew's complete biography and his archived articles, click here. You can reach Matthew by e-mail at