What Is Refrigerant?

Refrigerant is a substance in a cooling system, including heating, ventilation, and air conditioning units (HVAC) and refrigerators. The refrigerant is responsible for absorbing and releasing heat outside, which then cools the surrounding area, such as a room. Different types of systems can use different types of refrigerant, so it’s important to know the right one for your application. Below, I’ve outlined everything you need to know about this substance, including modern types, regulations, and more.

What is Refrigerant?

Refrigerant is found in various cooling systems, including air conditioners, refrigerators, process cooling systems, and heat pumps. It’s responsible for absorbing and releasing heat during the cooling process. Contrary to popular belief, your air conditioning system isn’t cooling the air within your home — it’s simply moving heat from inside to outside, using refrigerant. You might often hear it called “Freon,” but Freon is actually a specific brand name.

Refrigerants have properties that make them ideal for heat transfer and use in our everyday appliances, including:

• High latent heat to absorb substantial amounts of heat per unit of refrigerant.
• High liquid density to house more cooling capacity in a compact container.
• Low boiling point to absorb heat and undergo phase change even at low temperatures.
• Low specific heat and high latent heat to maximize heat transfer.
• Low viscosity to flow smoothly through system components.
• Nonflammable and nontoxic for safe operation.

What is the Refrigeration Cycle?

The cooling process of an HVAC unit is done through the refrigeration cycle. During this process, the refrigerant will undergo several phase changes. Here’s a quick look at how it works in an air conditioning system:

1. The compressor, located outside converts the refrigerant from a low-pressure, low-temperature gas into a high-pressure, high-temperature gas. It’s then pumped through the system.
2. The condenser coils release the heat from the refrigerant outdoors and change the gas into a high-pressure liquid.
3. The expansion valve controls the flow of refrigerant into the evaporator, reducing its pressure.
4. The refrigerant moves into the evaporator coils, found inside, and the refrigerant absorbs indoor heat, turning it back into a low-pressure gas. Cooled air is circulated into the indoor space.
5. The refrigerant returns to the compressor and the cycle repeats.

Types of Refrigerants

There are several types of refrigerants available. They all have different types of applications, and can’t be mixed. They also shouldn’t be substituted for one another, as they have varying properties that can cause damage or unwanted chemical reactions. The cost of refrigerant can vary by type.

The American Society of Heating, Refrigerating, and Air Conditioning Engineers (ASRAE) uses the refrigerant numbering system. This is the standardized method of identifying refrigerant to enhance safety and system operation. While many refrigerant cylinders may use color codes, these identifiers aren’t always reliable. You could find that one type of refrigerant from two different manufacturers comes in different colored cylinders. Instead, homeowners should always identify the refrigerant number, such as R22, R134A, and R32.

Here is a look at commonly used refrigerants, today and in the past:

CFC Refrigerants

Chlorofluorocarbons (CFCs) were widely used in the past thanks to their stability and performance potential. They contain chlorine, fluorine, and carbon. Common types were R11 in air conditioning systems and R12 in domestic refrigerators and freezers. 

However, CFCs were phased out under the Montreal Protocol in 1987 due to their high ozone depletion potential (ODP) and global warming potential (GWP). 

HCFC Refrigerants

Hydrochlorofluorocarbons (HCFCs), including R22 and R123, are made up of hydrogen, chlorine, fluorine, and carbon. While HCFCs have lower ODP and GWP compared to CFCs, they still contribute to ozone depletion and global warming. HCFCs are still found in existing air conditioners and chillers, but they’re currently being phased out. They’ll be completely removed from the market by 2030.

HFC Refrigerants

Hydrofluorocarbons (HFCs) contain hydrogen, fluorine, and carbon. This type of refrigerant doesn’t have an ODP, but tends to have a high GWP. Some kinds of HFCs are currently being phased out due to high GWP.

For example, the United States Environmental Protection Agency (EPA) banned R134a from use in new chillers in 2024 as it has a GWP of 1,430. It and other high-GWP refrigerants are being replaced with hydrofluoroolefin refrigerant blends (HFC/HFO) and low-GWP HFCs, including R32.

HFCs are widely used in refrigeration and air conditioning systems.

Hydrofluoroolefin Refrigerants

Hydrofluoroolefins (HFOs) have very low GWP and no ODP, making them very environmentally friendly, especially when compared to alternative refrigerants. They’re currently being adopted in new systems. For instance, many new vehicles now use R1234yf, which has a GWP of four and an ODP of zero.

Natural Refrigerants

Natural refrigerants are natural substances that can be used in various applications. They can have a low GWP and a zero ODP. However, they tend to pose challenges that hinder wider applications. Some types include:

• Ammonia is highly efficient, but is toxic and flammable. It’s used in some industrial processes.
• Carbon dioxide is non-flammable and non-toxic, but can only operate at high pressures. This can pose engineering challenges. It’s found in some commercial refrigeration systems, heat pumps, and vehicle air conditioning units. It’s also being seen more often in supermarkets, vending machines, and water coolers.
• Hydrocarbons are efficient but highly flammable. They can be used in some air conditioning and refrigeration systems.

Refrigerant Regulations

Various environmental regulations have restricted the use of certain refrigerants due to their potential to deplete the ozone and contribute to global warming. Some have completely been removed from the market, such as R11, and others are currently being phased out, including R134a. A few regulations that have passed that impact refrigerants are:

Montreal Protocol

The Montreal Protocol of 1987 is an international agreement to protect the ozone layer by phasing out the production and use of ozone-depleting substances. Commonly used refrigerants, including CFCs, were phased out and completely removed from the market by 1996. HCFCs are currently being phased out, and their production is due to completely end in 2030. 

The Montreal Protocol has been amended several times over the years. This includes the Kigali Amendment in 2016. This amendment specifically targets HFCs, which have replaced CFCs and HCFCs. HFCs don’t deplete the ozone, but they have a high GWP. The phasedown schedules for HFCs depend on the country and economic circumstances.

Kyoto Protocol

The Kyoto Protocol, signed in 1997 in Japan, is another international treaty. It’s based on the United Nations Framework Convention on Climate Change (UNFCCC). It focuses on all greenhouse gasses, which include some refrigerants. The agreement focuses on phasing out these substances with a high GWP and using alternatives.

American Innovation and Manufacturing Act of 2020

The American Innovation and Manufacturing Act of 2020 (AIM) is geared towards phasing out HFCs in the United States. Under it, HFCs that exceed the act’s GWP limit are to be removed from the market. For example, HFC refrigerants used in residential air conditioners that have a GWP of over 700 can’t legally be manufactured after January 1, 2025.

Refrigerants are essential in cooling systems, but various types can be harmful to the environment due to their high ODP and GWP. However, even as some are phased out, it’s important to use the right refrigerant for your household appliance. This will help ensure cooling and system efficiency, and reduce the potential for HVAC damage.