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Air conditioner refrigerant is the magical substance that makes air conditioning possible. Its ability to quickly change states is what allows us to cool (or heat) our homes, offices, and commercial buildings, keeping us sweat-free and blissfully comfortable.
In this article, we explore the science behind air conditioner refrigerants, and how it works as part of the air conditioner’s refrigeration cycle. We also delve into the most common refrigerant in Australia—R-32—and touch on how much refrigerant an AC system needs. Let’s jump in.
What is air conditioner refrigerant & how does it work?
Chlorofluorocarbon (CFC) air conditioner refrigerant was created by the American chemical company DuPont in 1928, as a replacement for the flammable and highly toxic substances used in fridges. CFC made fridges much safer, but unfortunately, was discovered to be a potent greenhouse gas, thousands of times more warming than CO2. It also eats away at the earth’s ozone layer, which prompted the development of hydrofluorocarbons (HFCs, branded as Freon)—a safer, more environmentally-friendly substance that is still used today.
There’s about ten types of refrigerant used in air conditioners today, but the most common for residential and commercial systems is R-32.
R-32 and other refrigerants are the lifeblood of air conditioners. They are the substance that allows the whole refrigeration process to work, due to their ability to quickly change states. During the refrigeration cycle, the substance changes from a cool liquid, a vapour, and hot gas, caused by pressure changes from the air conditioner’s components. The system uses these state/temperature changes to produce cool or hot air for a building.
The refrigeration cycle is complex and a little counterintuitive, but here’s a breakdown of how it works, including an accompanying diagram to help:
Original image from Torr Engineering
- The refrigerant enters the compressor as a low-pressure, superheated gas.
- The compressor pumps the gas towards the condenser, where it cools and condenses, turning into vapour and then a cool, high-pressure liquid. This process produces hot air, which the condenser (contained in the outside unit) blows away with a fan.
- The liquid arrives at the metering device, which lowers its pressure and turns it back into a vapour.
- The vapour enters the evaporator, where it absorbs heat from the space being cooled. This causes the vapour to boil, which turns it back into superheated low-pressure gas. This process produces cool air, which the AC unit’s fan blows into the room.
- The gas enters the compressor, for the cycle to start over.
(Check out our Air Conditioning Vocab article if you’d like to learn more about these terms).
For those that remember basic chemistry, this might seem odd. How can refrigerant be both superheated and low-pressure? But this is the beauty of the substance—its unique chemical makeup gives it a boiling point and critical temperature that allows this to occur, which is why we’re blessed with fridges, freezes, and air conditioning.
R-32 has a lifespan of between seven and 17 years. If an air conditioner’s refrigerant levels are too low, a technician will need to top them up with the same type of refrigerant. If another type of refrigerant is used, the mixture is “contaminated” and may perform badly, as well as damage the air conditioner’s parts. Air conditioning technicians require a refrigerant handling licence (RHL) to buy and use R-32.
In Australia, dead refrigerant is sent to a plasma arc plant to be destroyed. This plant uses temperatures of 10,000°C to break down the fluorocarbon waste into safer acid gases,1 which don’t contribute to global warming.
These are some other common types of refrigerant still used today:
- R-290 (propane)
How much refrigerant is in a home air conditioner?
The amount of refrigerant in a home air conditioner depends on the size of the system, the length of copper line, and the size of the evaporator coil, so there’s no simple answer here. You can use this general rule of thumb though: an AC system requires 2-4 pounds per ton of cooling. So if your system provides 2-ton of cooling, it will require between 4-8 pounds of refrigerant3.
What is R32 refrigerant?
R-32 is a hydrofluorocarbon substance, made up of two hydrocarbon molecules and two fluorine molecules, which create a structure that looks like a plus symbol. It’s colourless, odorless, and efficiently carries heat, has a low flammability score, and a high operating pressure, which is why it’s become one of the most commonly used refrigerants for Australian air conditioners, used in around 71% of the residential and commercial market2.
R-32 has a global warming potential of 675, which means that it’s 675 times more potent than CO2. By comparison, one of the worst “R” DuPont refrigerants has a GWP of 14,800, so R-32 remains an environmentally-friendly choice. It’s also completely ozone-friendly, unlike the earlier chlorofluorocarbon (CFC) and hydrochlorofluorocarbon (HCFC) substances. Here’s the environmental impact of R-32’s compared against other common refrigerants:
Image from Daikin
Here are the technical properties of R-32:
Saturation pressure at 4°C
Saturation pressure at 4°C
A2L (lower flammability)
Air conditioner refrigerant leak symptoms
Refrigerant leaks can happen for a variety of reasons. The technician’s process may be sloppy when they’re adding, removing, or topping the refrigerant up, the copper pipe that holds the refrigerant may corrode and erode over time, or there may be a factory defect in the AC system itself.
Large refrigerant leaks are a concern, because when inhaled, refrigerant cuts off your oxygen supply. When inhaled in large amounts, this can kill you4.
Thankfully, there’s plenty of signs of refrigerant leaks that can alert you to a leak:
- The system’s airflow seems low, because it can’t produce as much cool air as usual. This causes your property to cool down much more slowly.
- The system is blowing warm air instead of cool air.
- There’s a hissing sound coming from the indoor unit.
- You have unusually high electric bills, which arrive consistently.
If you’d like to learn more about potential problems with your system, check out our guide on Air Conditioning Troubleshooting.
Refrigerant is an extraordinary substance that has allowed us to accurately regulate the temperature of our homes, and preserve our food in fridges and freezers. With the creation of R-32, and the continued development of better refrigerants, we’re keeping our precious lifestyle while helping to mitigate global warming.
We hope this article has been useful. Thanks for reading!
- Refrigerant reclaim – an update, AIRAH
- R32 Refrigerant information for technicians | ARC Industry Site, ARC
- How Much Refrigerant Is In A Home Air Conditioner, HSI
- Jenna Fletcher, 2018, Refrigerant poisoning: Causes, symptoms, and treatment, Medical News Today