When your AC isn’t cooling as it should, the culprit isn’t always a faulty compressor or clogged filter—it could also be the refrigerant.
Many factors influence HVAC refrigerant choice. This is because the type of refrigerant in your HVAC system plays a critical role in its performance, efficiency, and environmental impact.
This guide will discuss different types of refrigerant used in HVAC systems of homes and commercial spaces, the upsides and downsides of each one, and regulations and considerations for choosing a refrigerant.
What is Refrigerant and Why Does It Matter?
Refrigerant is the fluid in AC or heat pump systems that is responsible for heat transfer.
It is primarily used in cooling devices like air conditioners, refrigerators, etc. The refrigerant is a heat-conducting material that can absorb and carry the heat before disposing outside. In devices like heat pumps, refrigerant also carries the heat inside from outside.
Some refrigerants, like CFC, are found to harm both the ozone layer and global climate. This led to the rise of environmentally friendly refrigerants.
Some refrigerants can be flammable and toxic too. So, leaks in refrigerant lines can be a safety hazard. Handling any sort of refrigerant issues must be done with care.
How Does Refrigerant Work?
The refrigerant works in a four-phase cycle:
- Compression: The refrigerant is in a low-pressure gas form in the beginning. At the compressor, its pressure and temperature rise. This makes the refrigerant a hot, high-pressure gas.
- Condensation: After moving to the condenser, the refrigerant releases the heat and becomes a high-pressure liquid.
- Expansion: The high-pressure liquid then becomes a low-pressure liquid through expansion at the expansion valve.
- Evaporation: In the evaporator, the liquid becomes a low-pressure refrigerant gas again. At this stage, it is ready for heat absorption again too.
The cycle keeps repeating and the AC keeps on cooling the indoor space with each cycle.
How Refrigerants Affect Air Conditioner’s Performance
Refrigerants work by absorbing and releasing heat. Different chemicals have this capacity at different levels. With varying thermodynamic properties, the type of refrigerant used in HVAC directly affects its efficiency.
Sometimes, the choice of refrigerant can impact the whole HVAC system. Some refrigerants may require larger or smaller components to operate. It can change the whole design and performance of the system.
Again, more conductive refrigerants can take some pressure off the compressor and evaporator. So, the efficiency of the refrigerant can reduce the workload of the compressor. It reflects on electricity bills and environmental impact.
A Brief History of Different AC Refrigerant Types
In the 18th and 19th centuries, scientists discovered different evaporating liquids can produce a cooling effect.
The first vapor compression system was invented in the 19th century. It used ether, sulfur dioxide, and methyl chloride as refrigerants. They pose high safety risks because of being toxic and flammable.
In the 1930s, CFC or chlorofluorocarbons were introduced as the “miracle” refrigerant. This chemical was non-flammable, non-toxic, and highly effective. There were different types of effective CFCs like Freon.
In the 70s, CFCs were linked to the ozone layer damage. In 1987, a gradual phase-out of CFC and other ozone depletion material was agreed upon internationally.
Hydrofluorocarbons (HFC) became the next generation of refrigerants to meet the demand. They aren’t harmful to the ozone layer. However, they are still a greenhouse gas and contribute to global warming.
The focus currently has shifted more towards using low to no global warming potential (GWP) with zero ozone depletion. So, hydrofluoroolefins (HFO), natural refrigerants like carbon dioxide and ammonia, and other innovative solutions are on the rise in the HVAC industry.
Common Types of HVAC Refrigerants
We have discussed the usage of different types of refrigerants over the years. So, what are the different types of refrigerants used now?
Here are the different types of refrigerants used in commercial HVAC and home AC systems:
Chlorofluorocarbons (CFCs)
CFCs are organic compounds made of carbon, fluorine, and chlorine atoms. They aren’t made naturally and so referred to as synthetic chemicals.
Examples of CFCs:
- R-12
- R-11
- R-113
- R-114
Note: “R” in the codes stands for refrigerants. The number that follows after the hyphen is based on the chemical structure of the refrigerant.
Usage:
Because of having high ODP, this refrigerant is gradually being phased out globally. Their production and import are already banned in many countries.
Hydrochlorofluorocarbons (HCFCs)
HCFCs also contain carbon, fluorine, and chlorine but they also have hydrogen atoms. This presence of hydrogen makes them less stable in the atmosphere. So, the ODP is lower for these refrigerants.
While less harmful to the environment, the refrigerant still has some ozone depletion potential (ODP). So, they are also being phased out as a part of the protocol.
Examples of HCFCs:
- R-22
- R-132
- R-124
- R-141b and R-142b
Usage:
The refrigerant’s use in newer ACs and other equipment is banned. Only the existing systems with HCFCs are allowed to operate. They are being replaced by HFCs, HFOs, and other natural refrigerants.
Hydrofluorocarbons (HFCs)
HFCs are made of hydrogen, carbon, and fluorine atoms. They are also synthetic materials. As chlorines are not in these compounds, they don’t deplete the ozone layer.
Having no impact on the ozone layer, this refrigerant is a potent greenhouse gas. As a result, it contributes to global warming. Considered a good replacement initially, this refrigerant is also being phased out gradually.
Examples of HFCs:
- R-410A
- R-134a
- R-32
- R-143a
Usage:
R-410A is a common refrigerant in newer systems. R-32 and HFOs are gaining popularity as replacements for R-410A. R-134a is often used in automotive air conditioning.
Hydrofluoroolefins (HFOs)
HFOs are made of hydrogen, carbon, and fluorine atoms. The main difference from HFCs is their molecular structure. This structural difference is the cause behind the difference in their properties.
These synthetic refrigerants have zero ODP and are much more environmentally friendly than HFCs. HFOs are considered to be the solution for making refrigerants more eco-friendly.
Examples of HFOs:
- R-1324yf
- R-1234ze
Usage:
R-1234yf is increasingly being used in automotive AC and other applications. R-1234ze is used in some chillers in industrial settings.
Natural Refrigerants
These refrigerants can be found or occur naturally in the environment. They are not synthetic chemicals created in labs.
Natural refrigerants have almost no global warming and ozone-depleting potential. They are environmentally friendly too. However, these refrigerants have some safety concerns.
Ammonia and propane are flammable. Ammonia is toxic too. Carbon dioxide operates at high pressure and can cause carbon dioxide poisoning.
Despite these safety issues, they are used with safety measures in place because of their low environmental impact.
Examples of Natural Refrigerants:
- Ammonia (R-717)
- Carbon Dioxide (R-744)
- Propane (R-290)
Note: There is also a different kind of blended refrigerants (e.g., R-407C, R-438A). They are often used as replacements for discontinued refrigerants like R-22.
Refrigerant Types for Residential Air Conditioning Systems
Different systems like window AC or industrial chillers have different cooling requirements. So, they are bound to use different types of refrigerants.
In home systems, air conditioner refrigerants are often selected based on safety, energy efficiency, and environmental-friendliness. There are other factors like availability, cost, and compatibility with the system which also play a role.
Here are the different types of refrigerants used in residential AC or HVAC systems:
| Refrigerant | Used In | Description |
| R-22 (Freon) | Older systems | It has been the workhorse for residential AC for decades. As an HCFC, it is going to be phased out soon. |
| R-410 (Puron) | Current systems | This is the most common one in current systems. This refrigerant has a high GWP. |
| R-32 (Difluoromethane) | Newer systems | It is becoming more common as regulations are pushing towards a more environmentally friendly system. |
| R-454B | Newer Systems | This is an advanced version of the R-410 (Puron). It has a lower GWP that R-410 doesn’t have with all the benefits. |
With the rise of HFOs, we can expect to see more of them in future systems. If you’re uncertain about your system’s refrigerant, check the manual or call an HVAC professional. They can also give you necessary maintenance or upgrade solutions for your refrigerants.
Environmental and Regulatory Considerations
Besides its performance, great emphasis is given to how a refrigerant will react with the environment.
Environmental Considerations
The whole HVAC trend is shifting towards environmental friendliness and for a good reason. For refrigerants, the environmental considerations are:
- Ozone-depleting potential
- Global warming potential
- Leakage of refrigerants in the system
- The efficiency of refrigerants affects the energy consumption of the system
Regulatory Considerations
The Montreal Protocol is the international agreement that took place in 1987. It mandated the phasing out of harmful substances like CFCs and HCFCs. The Kigali Amendment of this protocol also focuses on phasing down the use of HFCs to reduce global warming.
On a national level, many countries have adopted the protocol. This created regulations like:
- Phase-out schedules for specific refrigerants
- Restrictions on certain refrigerant chemicals
- Requirement for leak detection and repair
- Standards for refrigerant handling and disposal
For industrial uses, organizations like ASHRAE develop standards for refrigerant classifications, safety, and handling.
The Balancing Act
Choosing a refrigerant is a delicate balance between different factors:
- Minimizing environmental impact with low to no ozone damage and global warming
- Ensuring safety with low toxicity and flammability
- Maximizing cooling performance
- Minimizing energy consumption
- Considering the cost and availability of refrigerants
- Adhering to all applicable regulations
In the future, we are expected to see newer substances as refrigerants that have no ODP and GWP. Advancements in technology will also improve leak detection and prevention potential.
Conclusion
Different systems use different refrigerants depending on the requirements and compatibility. Different synthetic chemicals have been used over the years to meet this demand and efficiency. With environmental concerns, natural chemicals have come full circle again.
Synthetic refrigerants have good performance but with negative impacts on the environment. Natural refrigerants are environmentally friendly but can create safety hazards and are not as efficient sometimes. Consult a professional to find out the best one suited for you and your system that maintains all the regulations.
FAQ
Q. Can I switch refrigerants in my existing HVAC system?
A: While it is possible, switching the refrigerant is not as straightforward. Often, the AC unit, heat pump, or HVAC system as a whole is designed to work with a particular refrigerant. Changing the refrigerant in those cases requires some major modifications like replacing components like the compressor, and expansion valve. It’s generally more cost-effective to change the entire system in some cases.
Always talk to an expert before switching refrigerants.
Q. How do I know which refrigerant my system uses?
A: You can easily find the refrigerant used in your system in the manual, the unit’s nameplate, or the data sticker on the outdoor unit. It is often labeled as “Refrigerant Type” or “Refrigerant Charge”.
Q. Are natural refrigerants safe for home use?
A: Natural refrigerants can cause some safety hazards. Ammonia and propane are flammable. Leaks of these gases can cause fire. Carbon dioxide can also cause intoxication.
However, they are still best in terms of lowering environmental impact. Especially, when you can take safety measures and install safety devices to protect against those dangers.
Q. What should I do if my system uses R-22?
A: R-22 is no longer produced. Continuing to use the refrigerant can be expensive and is not a long-term solution. In some cases, you can retrofit the system to use newer refrigerants like R-407C or R-438A.
If your system is using R-22, the system is likely very old and well past its usual service period. It is often better to replace those units anyway. Even ignoring the refrigerant issues, a newer system will be a good investment in every way.
