Basic Understanding of Refrigerant Types:
HCFC, HFC, CFC, HFO, A2L, and HC

HVACR Licensing & Continuing Education

Basic Understanding of Refrigerant Types:
HCFC, HFC, CFC, HFO, A2L, and HC

by Jonathan Kilburn

Refrigerants are the backbone in the HVAC industry, enabling heat transfer and providing efficient cooling and heating solutions. Over the years, various types of refrigerants have been developed, each with unique chemical compositions, performance characteristics, and environmental impacts. This article provides an in-depth look at the primary refrigerant types—HCFC, HFC, CFC, HFO, A2L, and HC—and explains why some are no longer widely used due to regulatory restrictions. It also clarifies that even restricted refrigerants can often still be purchased for specific applications. The process for ending production and use of a refrigerant is called a ‘phase out.’ During the phase out process new refrigerant blends, alternative refrigerants, or replacement refrigerants are produced, primarily for industrial refrigeration, which allows for use of expensive equipment that is not easy to replace.

CFC (Chlorofluorocarbon) Refrigerants

CFCs were among the first widely used refrigerants in HVAC systems, with R-12 being one of the most common examples. These refrigerants are composed of carbon, chlorine, and fluorine, making them chemically stable and highly effective at heat transfer. These became the first manmade chemicals used in chillers and air conditioners commercially.

Despite their effectiveness, CFCs are no longer produced due to their significant environmental impact. The high chlorine content in CFCs contributes to the depletion of the ozone layer when released into the atmosphere. The Montreal Protocol, established in 1987, and EPA (Environmental Protection Agency) phased out the production of CFCs globally to protect the ozone layer (ODP). However, CFCs can still be found in older equipment and may be purchased for servicing such systems, though availability is limited and heavily regulated. Later variations of CFCs, like R502 an azeotropic mixture of R115 CFC and R22 HCFC, were a short term retrofit stop gap to reduce some of the potential hazards and increase availability.

HCFC (Hydrochlorofluorocarbon) Refrigerants

HCFC refrigerants were introduced as transitional refrigerants to replace CFCs, offering lower ozone-depleting potential. R-22 is the most notable example of an HCFC and was widely used in air conditioning and refrigeration systems for decades and the first step towards reducing potential climate change and ozone damage.

While HCFCs are less harmful to the ozone layer than CFCs due to the reduced concentrations of molecular chlorine, they still contribute to ozone depletion and are being phased out under the Montreal Protocol. The production and import of R-22, for instance, have been banned in many countries, though reclaimed and recycled HCFCs can still be used for servicing existing systems. Technicians may purchase HCFCs, but their use is discouraged as the industry transitions to more environmentally friendly alternatives in air conditioning systems.

HFC (Hydrofluoroolefin) Refrigerants

HFOs represent the next generation of refrigerants, developed to address both ozone depletion and global warming concerns. Despite the fluoroolefin name, HFOs are a fluorocarbon base just containing a multiple carbon atom bond (Olefin) instead of a single carbon atom bond. Composed of hydrogen, fluorine, and carbon, HFOs have a chemical structure that enables a low global warming compared to HFCs even with the same chemical compound base. R-1234yf and R-1234ze are common examples of HFOs, used in automotive air conditioning and commercial refrigeration.

HFOs are highly energy-efficient and environmentally friendly with their low boiling point and lack of carbon atoms, making them a preferred choice for new HVAC systems. However, their adoption has been slower in some regions due to higher costs and limited availability. As regulations phase down HFCs, HFOs are expected to become more prevalent, especially in applications requiring compliance with stringent environmental standards.

A2L Refrigerants

A2L refrigerants are a subset of refrigerants characterized by low flammability and low toxicity but are still flammable refrigerants. This is a safety classification. The difference between A2 and A2L refrigerants is the flammability; A2 being more flammable than A2L. Many HFOs and some HFC blends, such as R-32, fall into these categories. A2L refrigerants are designed to provide a balance between environmental performance and safety, with lower GWP than traditional HFCs. Thermodynamic properties taken into account, A2L refrigerants surpass many current refrigeration choices popularized by the industry. The ASHRAE has begun to offer more information about the potential advancements of A2L refrigerants.

While A2L refrigerants offer significant environmental benefits, their low flammability rating requires additional precautions during installation and servicing. HVAC technicians must be trained in handling A2L refrigerants safely, and specialized tools and equipment may be required. Their use is increasingly common in new systems, particularly as the industry moves toward refrigerants with lower GWP.

Why are Some Refrigerants No Longer Widely Used?

The phaseout of certain refrigerants, such as CFCs and HCFCs, stems primarily from their environmental impact. These substances contribute to ozone depletion and global warming, prompting international agreements like the Montreal Protocol and Kigali Amendment to regulate their production and use. HFCs, while ozone-friendly, are also being phased down due to their high GWP.

Regulations do not always prohibit the purchase or use of phased-out refrigerants. Instead, they often restrict production and new system designs using these substances. For example, reclaimed or recycled CFCs and HCFCs can still be purchased for servicing existing equipment, allowing systems to operate until they reach the end of their life cycle. This ensures a smooth transition to newer refrigerants while minimizing disruption.

During these transition stages, new refrigerants are often substituted. It becomes difficult when encountering mixes like ternary blends, that contain various classifications of refrigerants.

Choosing the Right Refrigerant

The choice of refrigerant depends on several factors, including environmental regulations, system compatibility, and safety considerations. For new installations, HFOs, A2Ls, and HCs are increasingly favored due to their low environmental impact. Existing systems may still rely on HFCs or even HCFCs, depending on availability and regulatory requirements. There is no easy swap retrofit between the types of refrigerants as internal components, like compressors and condensers, rely on the specific chemical compositions. This can become increasingly costly for commercial applications like supermarkets that may rely on an HCFC 22 and unable to obtain it at a reasonable price due to phase-out despite the GWP refrigerant (global warming potential) ratings. Countries in Europe lead the way in freon (refrigeration) development and use.

HVAC technicians must stay informed about refrigerant trends and regulations, as the industry continues to evolve. Proper training and understanding of refrigerant handling are essential for ensuring compliance, safety, and optimal system performance. By embracing environmentally friendly refrigerants and adapting to regulatory changes, technicians can contribute to a more sustainable future while meeting the needs of their clients.