How Many Types of AC Refrigerants are there?
A refrigerant is a chemical compound that absorbs heat from one medium and in the process cools it. Ideally, a good refrigerant should have a low boiling point and high latent heat of vaporization.
With a low boiling point, the refrigerant will evaporate easily and as it evaporate take away with it heat from the medium/surface it is in contact with. Latent heat of vaporization is basically the heat absorbed as the refrigerant turns from liquid to gas. The higher the better.
There are 2 main types of refrigerants. These are organic and inorganic refrigerants. Inorganic refrigerants include ammonia, air, carbon dioxide and sulfur dioxide. Organic refrigerants include hydrocarbons, halocarbons and azeotropes.
Inorganic refrigerants have fantastic heat transfer properties but are toxic. Although they were exclusively used before introduction of hydrocarbon refrigerants, they are still in use (in commercial installations) due to their great thermodynamic properties.
Hydrocarbon refrigerants have good thermodynamic properties and are used in commercial and industrial installations. They are however explosive and highly flammable.
Examples of hydrocarbon refrigerants are ethane, propane, butane, isobutene, ethylene and propylene.
The type of refrigerants used in residential air conditioning are called halocarbons. Basically, a halocarbon is a compound derived from a hydrocarbon by replacing a hydrogen atom with a halogen atom (chlorine, fluorine, bromine etc.).
Halocarbon refrigerants are further divided into 3 groups. The difference between them is their chemical formula which then gives them different chemical and physical properties.
The 3 types of refrigerants used in air conditioning are chlorofluorocarbons (CFCs) hydrochlorofluorocarbons (HCFCs) and hydrofluorocarbons (HFCs). An example of CFC is R-12, HCFC is R-22 while that of HFC is R-410A.
Refrigerants can further be divided as primary or secondary refrigerants. Primary refrigerants absorb heat directly from the medium/surface and undergo a cycle. Secondary refrigerants are first cooled by a primary refrigerant before absorbing heat from the surrounding, with no phase change.
Examples of primary refrigerants are R-11, R-22 and R-134A. Those of secondary refrigerants are brine and dry carbon dioxide. Basically secondary refrigerants are used in high-temperature applications to minimize the load on primary refrigerants.
Types of Refrigerants
Let us now look at the 3 types of refrigerants used in residential air conditioning in more details.
1. Chlorofluorocarbons (CFCs)
Chlorofluorocarbons (CFCs) are organic substances containing carbon, fluorine and chlorine atoms. They are nontoxic and nonflammable. Apart from use as refrigerants, CFCs are used in aerosol sprays, blowing agents for foams and packing materials and also as solvents.
An example of a CFC refrigerant is R-12 (dichlorodifluoromethane) which is also commonly known as Freon-12.
CFC refrigerants were developed in 1928 as a possible alternative to inorganic refrigerants like ammonia. As I have mentioned, although inorganic refrigerants had great thermodynamic properties, they were toxic and corrosive.
Although these (CFCs) refrigerants managed to eliminate the problems caused by inorganic refrigerants, they introduced one main challenge that could not be wished away. CFC refrigerants were discovered to have a very high global warming potential.
A study carried out in the 1970s found out that CFC refrigerants posed a threat to the environment because once they were released in the environment, they would accumulate in the stratosphere and destroy the protective ozone layer.
CFCs are chemically very stable. As a result, they can remain active in the environment for up to 100 years.
The production of CFC refrigerants was stopped in 1994 in favor of other “better” refrigerants.
2. Hydrochlorofluorocarbons (HCFCs)
When CFC refrigerants, stopped being produced, they were replaced by hydrochlorofluorocarbons (HCFCs). The most common type of HCFC refrigerant is R-22 usually known by its brand name Freon.
The difference between hydrochlorofluorocarbons and chlorofluorocarbons is that hydrochlorofluorocarbons contains a hydrogen atom in their structure, unlike chlorofluorocarbons.
The extra hydrogen atom in HCFCs decreases their stability, thereby reducing their lifetime in the atmosphere. It was expected that this would considerably reduce the impact on the environment caused by CFC refrigerants.
That however did not work out. Several studies later discovered that HCFC refrigerants caused the depletion of the ozone layer and ultimately resulted in global warming.
According to the United Nations Environmental Program (UNEP), the most commonly used hydrochlorofluorocarbon (HCFC) is nearly 2000 times more potent than carbon dioxide in terms of its global warming potential.
As per the Montreal protocol, countries started a systematic process to phase out HCFC refrigerants. In United States, the manufacture of air conditioning systems using Freon was stopped in 2010.
After 10 years (January 2020 to be precise), the production and importation of Freon was stopped. You can however still find recycled Freon or from old stock but the price is very high.
There are still many air conditioners in the United States which still use Freon. That by the way is not illegal.
To find out which refrigerant your air conditioner uses, just look at the nameplate on the outside/condenser unit. The user-manual will also have that information.
3. Hydrofluorocarbons (HFCs)
Hydrofluorocarbons refrigerants are in essence the third-generation refrigerant gases. They are the refrigerants found in modern air conditioners.
The most common HFC refrigerant is R-410A, also known by its brand name Puron. HFC refrigerants were developed to solve the problem brought about by the first 2 types of refrigerants (CFCs and HCFCs).
They main difference between HFC and the other two refrigerants is that they do not contain a chlorine atom, which is responsible for the global warming mess. HFCs are made up of hydrogen, fluoride and carbon atoms.
Having said that, it is still too early to say with certainty that HFC refrigerants have zero global warming potential. As a matter of fact, there are some indications that HFCs could even have a higher global warming potential than HCFCs.
It looks like the search for a good refrigerant is far from over.
Different Types of AC Refrigerants
And now the following are the different types of refrigerants based on their chemical formula, some of which are identified by their brand names:
R-22 Refrigerant
- Commonly known by its brand name Freon
- ACs using Freon stopped being manufactured in in 2010
- Production and importation stopped in 2020
- It is a HCFC
- 2000 more potent than CO2 in global warming potential
- Still available from recycled and old stock
- Depletes the ozone layer
R-410 Refrigerant
- It is a HFC
- Has no chlorine atom hence doesn’t deplete ozone layer
- Commonly known by its brand name Puron
- ACs using R-410A need a pressure rating higher than those of R-22 by 50%
- Used in modern air conditioners
R-407C Refrigerant
- Commonly known by its brand names, Suva® 407C or Genetron® 407C
- It is a HFC
- Does not directly contribute to global warming
- Equal operating properties/characteristic of R-22
- Lower efficiency
- Offers easy conversion to R-22 systems due to similar operating characteristics
R-134A Refrigerant
- It is an HFC
- Used as a replacement for R-12 in in centrifugal, rotary screw and reciprocating compressors.
- Used in newer car AC systems
- Zero ozone depletion level
Unfortunately, refrigerants cannot be mixed. For instance if your air conditioning is designed to use R-22 refrigerant, you cannot top it up with R-134A. It will simply not work.
As I have mentioned above, different refrigerants have different chemical and physical properties. For instance, the operating pressure for AC systems using R-140A is 50% more than those using R-22 which makes mixing the 2 refrigerants out of the question.
Although conversion kits are available, the process is not cheap and results are hard to guarantee. You are better off buying a new air conditioning system.
Conclusion
And basically those are the many types of refrigerants used in air conditioning. Most folks think that all refrigerants are also called Freon. Now you know that is not the case.