For many homes, the HVAC system is vital for comfort. It keeps us warm in winter and cool in summer, but you may not be aware that HVAC equipment doesn’t actually produce cold air. Instead, it uses heat or thermal energy transfer to move the hot air from one location to another. Heat flows from the higher temperature areas to areas with a lower temperature. This is the Second Law of Thermodynamics, and your HVAC system has the responsibility to reverse this natural flow. The heat exchanger in your HVAC system is a vital component in the process of removing hot air from your home and delivering inside buildings during the colder weather. So, here we’ll explore a little more about heat exchangers and why they are so vital for your HVAC system.

The Heat Exchanger Basics

In simple terms, the heat exchanger in your HVAC system is a device to transfer thermal energy from a medium to another. A heat exchanger can not only be used to heat or cool a home or building, but it can also help engines and machines operate more efficiently. How the heat exchanger works will depend on the specific equipment. There are a number of options for heat exchanger devices in HVAC equipment, from heat pumps to furnaces and air conditioners. We’ll explore the two most common options here, so you can gain an understanding of how heat exchangers operate in different scenarios and types of equipment.

How Heat Exchangers Are Used By Air Conditioners

The air conditioner is one of the most common pieces of HVAC equipment that employs a heat exchanger. It removes heat from inside a home or building and transfers it outside. In order to complete this process, the air conditioner relies on refrigerant. This chemical is kept in a closed system inside your air conditioning system to allow the heat transfer process to be performed efficiently.

The refrigerant absorbs, carries and releases heat as it transforms between a gas and liquid state and back again during the entire refrigeration process. The refrigerant moves through the various components, carrying heat as it goes.

The entire cooling process begins with the refrigerant in the evaporator coils as a low pressure liquid. A fan is used to blow warm air across the coils drawn from inside the room or area. As the heat is absorbed from the air, the refrigerant changes into a gas vapor to cool the room.

The low pressure gas refrigerant now travels to the compressor inside the outdoor unit where it is converted into a hot, high pressure gas. The refrigerant now moves to the outdoor condenser, and as air passes over the condenser, the heat from the refrigerant is carried away. This causes the refrigerant to convert into a cool, high pressure liquid.

The refrigerant is now cooled further in the expansion valve before it is moved to the evaporator to begin the process again.

Although the entire air conditioning system may be considered a heat exchanger, the part responsible for transferring heat from inside to outside is the condenser, while the refrigerant is the medium used for this process.

How a Heat Exchanger is Used By a Gas Furnace

Another common piece of HVAC equipment employing a heat exchanger is the gas furnace. Gas furnaces have been popular for heating homes for decades. Gas furnaces provide consistent, reliable and efficient heating in even the coldest winters, employing heat exchangers to move warm air throughout the desired area. Typically gas furnaces use a heat exchanger to increase the air temperature before it is delivered throughout the building using registers and ducts. In gas furnaces, the heat exchanger is actually an airtight vessel. It has a hole at the bottom and at the top called a flue.

The heat exchange process in a gas furnace begins when burners generate combustion gases to deliver them to the first opening of your heat exchanger. As this occurs, a blower moves indoor air over the outside of the heat exchanger. The heat exchanger warms the air using the combustion gases. This warmed air is then distributed through the ductwork to increase the temperature in different rooms of the building. The exhaust gases produced during this combustion process are released outside the building via the flue.

There are two roles of the heat exchanger in gas furnaces. It is needed to exchange heat to the air from the combustion process and also keep toxic gases from the combustion process separate from the warmed air.

Maintaining Your HVAC Heat Exchangers

Heat exchangers perform the heavy lifting of heating or cooling a building to keep us comfortable in summer or winter. These components are designed to use less energy during the heating and cooling process for a more energy efficient system.

As such a vital component of your HVAC system, it is essential to ensure that your heat exchangers continue to operate efficiently. Without the heat exchanger in your furnace or air conditioner, the system would fail to operate. For example, if your air conditioner has a refrigerant leak and the condenser coils ice over, the entire system will stop delivering cooled air inside your home. Fortunately, regular servicing and maintenance can help to prevent problems with your heat exchangers. An experienced HVAC technician can assess your system and perform any necessary preventative maintenance. This involves checking for components showing signs of wear and replacing them before they can degrade further and fail. This will not only reduce your repair costs, but will also reduce the risk of a breakdown compromising your comfort when you need your HVAC system the most. Regular servicing will also boost efficiency so that you can enjoy your optimum comfort levels without a massive increase in your energy bills.

If you have concerns about your heat exchangers or any other HVAC components, be sure to contact an experienced HVAC repair specialist. A professional technician can assess your system and check for any underlying problems that could be compromising performance or efficiency.