Having the Right AC Refrigerant Matters
With a lot of focus on the transition to lower GWP refrigerants, as a facility manager or owner, you may wonder what this means for your existing systems and systems purchased ahead of the transition. Will it still be okay to service them? You will most likely be able to continue servicing your systems in the future, but it is important to understand the differences between HFC refrigerants. The most popular hydrofluorocarbon (HFC) refrigerants for new commercial air conditioning systems in the US today include R-410A, R-407C, and R-134a, but there are still plenty of R22 systems out there. The next generation fluids will have lower global warming potentials (GWP) but many are classified as mildly flammable. Outlined below are a few of the main differences between refrigerants along with some additional guidance on why selecting the correct refrigerant for the desired application matters.
R-22 Refrigerant
- Often referred to by a brand name, such as Freon®
- R-22 is a hydro-chlorofluorocarbon (HCFC) that contributes to ozone depletion
- As of 2010, R-22 was discontinued for use in new air conditioning systems
- As of 2020, the use of R-22 is limited to recycled or stockpiled quantities.
R-410A Refrigerant
- Often referred to by a brand name such as Puron®, Suva® 9100, or Genetron® AZ-20®
- It is a hydro-fluorocarbon (HFC) that does not directly contribute to ozone depletion with a GWP of 2088[1]
- R-410A operating pressures can be more than 50% higher than R-22, thus R-410A systems require components capable of working at these higher pressures
- R-410A is the most common refrigerant for new light commercial unitary air conditioning systems
R-407C Refrigerant
- Often referred to by a brand name such as Suva® 407C or Genetron® 407C
- R-407C is a hydro-fluorocarbon (HFC) that does not directly contribute to ozone depletion with a GWP of 1774
- Of the higher temperature HFC options, R-407C most closely matches the operating characteristics of R-22
- It is a high-glide refrigerant with lower efficiency, but provides the simplest conversion from R-22 due to its similar pressures
R-134a Refrigerant
- Widely used in many air conditioning and refrigeration systems globally
- It is a hydro-fluorocarbon (HFC) that does not directly contribute to ozone depletion with a GWP of 1430
- It is a single-component refrigerant with no glide, featured in many large commercial screw chillers
R-32 Refrigerant
- Widely used in many air conditioning and refrigeration systems globally
- It is a pure (single component fluid) HFC that does not directly contribute to ozone depletion with a GWP of 675
- Classified as A2L or mildly flammable
R-454B Refrigerant
- Widely used in many air conditioning and refrigeration systems globally
- It is a hydrofluorocarbon blend (HFO+HFC) that does not directly contribute to ozone depletion, with a GWP of 466
- Classified as A2L or mildly flammable
System manufacturers have had great success with R-410A because of its energy efficient properties and ease of use in their systems. In addition, components are widely available for designing efficient R-410A systems.
Many air conditioning models are designed to be used with R-410A for a reliable and more efficient operation. Because R-410A can absorb and release more heat than R-22, an air conditioning compressor can run at a cooler temperature, reducing the risk of compressor burnout due to overheating.
R-410A also functions at a higher pressure than R-22, so new compressors are built to withstand greater stresses. If someone were to put R-410A refrigerant into a system designed for R-22, the pressure could potentially be too high, causing the unit to potentially fail.
Most air conditioners use oil to keep the compressor lubricated during operation. R-22 air conditioners use mineral oil (MO) and R-410A systems use Polyol Ester Oil (POE). For cases when you are retrofitting a system to an HFC refrigerant, it is recommended to remove at least 95% of the MO before replacing it with POE oil. (NOTE: Under no circumstances should R410a be used to ‘top-off’ an R22 system, find out why here). POE oil is generally more soluble with R-410A than mineral oil is with R-22. This means the R-410A system operates more efficiently, reducing wear and tear on the compressor. What if I have a HCFC refrigerant, can I use alkyl benzene oils? The answer is probably, but only if it is approved by the compressor manufacturer. If you are unsure, always consult with the compressor manufacturer. For example, a list of refrigerants and lubrications approved for various CopelandTM compressors can be found here: 93-11 – Refrigerants and lubricants approved for use in Copeland™ compressors.
In addition, temperature glide is a property of some HFC refrigerant blends or mixtures and is generally undesirable. Because the composition alters during a phase change, there is a slight change in evaporating and condensing temperature at constant pressure. Commercial air conditioning systems that use higher glide refrigerants are usually designed to work around the problems associated with glide, with little or no effect on system performance.
As lower GWP refrigerants become available, it’s important to note it may not be possible to use all of them as a retrofit in existing systems because some have mildly flammable properties. Refrigerants should always only be used in systems specifically designed for them, as selected by manufacturers and system designers.
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1 IPCC AR4 100-yr GWP
Here are a few links to other articles on the topic of refrigerants:
