Refrigerant Types, Properties, and GWP Chart: Complete HVAC Refrigerant Guide

"My HVAC tech says my R-410A system is being phased out and I'll need R-454B next time. What's the difference between all these refrigerants? Can I just swap one for another?"

We hear this question constantly. With the EPA phasing down high-GWP refrigerants under the AIM Act, homeowners and technicians alike are trying to figure out which refrigerant does what, which ones are going away, and what's replacing them.

Here's the quick answer: R-454B (GWP of 466) is the designated replacement for R-410A (GWP of 2,088) in most residential and commercial AC systems. It delivers similar cooling performance but with a 78% lower global warming impact. You cannot simply swap it into an existing R-410A system — new equipment is required.

Below, we've built the most comprehensive refrigerant comparison chart you'll find anywhere. It covers all 10 major refrigerants with their properties, GWP values, safety classifications, oil compatibility, and applications — everything in one place. Let's dig in.

Master Refrigerant Comparison Chart

This is the chart. Every major HVAC and refrigeration refrigerant, side by side. We've included the type (HCFC, HFC, HFO, or natural), the Global Warming Potential or GWP, ASHRAE safety class, boiling point, compatible oil, and primary applications.

*R-744 (CO₂) sublimes at atmospheric pressure rather than boiling. Its critical temperature is only 87.8°F, which means it operates in a transcritical cycle in warm climates.

As you can see, the GWP values vary wildly — from R-744 at just 1 all the way up to R-404A at 3,922. That's the core reason the EPA is pushing for a transition to lower-GWP alternatives.

How ASHRAE 34 Refrigerant Classification Works

Every refrigerant gets a two-part safety classification under ASHRAE Standard 34. The first character (A or B) indicates toxicity, and the second character (1, 2L, 2, or 3) indicates flammability.

Let's break each one down.

Toxicity Classes: A and B

Class A means "lower toxicity." The Occupational Exposure Limit or OEL is 400 ppm or higher. Every common residential and commercial refrigerant — R-22, R-410A, R-454B, R-32, R-134a, R-404A, R-407C, R-290, R-744, R-1234yf — is Class A.

Class B means "higher toxicity" with an OEL below 400 ppm. The main Class B refrigerant you'll encounter is R-717 (ammonia), which is widely used in industrial refrigeration and ice rinks.

Flammability Classes: 1, 2L, 2, and 3

This is where it gets important for the current refrigerant transition:

• Class 1 (no flame propagation): Won't burn under test conditions at 140°F and 14.7 psi. Examples: R-22, R-410A, R-134a, R-404A, R-407C, R-744. These are the easiest to work with from a safety standpoint.

• Class 2L (lower flammability): Mildly flammable with a burning velocity ≤ 3.9 inches per second. Examples: R-454B, R-32, R-1234yf. This is the "new generation" classification driving the current transition.

• Class 2 (flammable): Burns faster than 2L. Example: R-152a. Rarely used in HVAC.

• Class 3 (higher flammability): Highly flammable. Example: R-290 (propane). Excellent thermodynamic properties but requires strict charge limits and safety measures.

What Is an A2L Refrigerant?

You'll hear "A2L" constantly in HVAC conversations right now. A2L means lower toxicity (A) combined with lower flammability (2L). It's the safety classification for R-454B, R-32, and R-1234yf.

Here's the deal: A2L refrigerants are mildly flammable, but their burning velocity is so low that ignition under normal operating conditions is extremely unlikely. ASHRAE 15 and UL 60335-2-40 establish the safety requirements for A2L systems, including leak detection and ventilation.

Individual Refrigerant Properties and Specifications

Let's go through each refrigerant individually. For each one, we cover the chemical composition, key properties, why it matters, and what it's used for.

R-22 (Freon): The Legacy Residential Refrigerant

R-22 (chlorodifluoromethane, also known as HCFC-22 or by the brand name "Freon") was the dominant residential AC refrigerant for decades. It worked well, was easy to handle (A1 safety class), and technicians knew it inside and out.

The problem? R-22 contains chlorine, giving it an Ozone Depletion Potential (ODP) of 0.055. Under the Montreal Protocol, R-22 was banned from use in new equipment as of 2010.

All production and import of R-22 was banned as of 2020. The only R-22 available now is reclaimed or stockpiled refrigerant.

R-22 Key Properties

If your system still runs on R-22, you can continue using it until the equipment fails. However, expect the cost of reclaimed R-22 to keep climbing as supplies dwindle.

When it's time to replace your system, the new unit will use either R-454B or R-32. For more on charging and superheat and subcooling by refrigerant type, check out our dedicated guide.

R-410A (Puron): The Current Residential Standard

R-410A is a near-azeotropic blend of 50% R-32 and 50% R-125. Carrier introduced it in 1996 under the trade name "Puron," and it became the dominant residential AC refrigerant after R-22 was phased out. It has zero ozone depletion potential and delivers excellent SEER ratings.

The catch? Its GWP of 2,088 is actually higher than R-22's. Under the EPA's AIM Act, R-410A exceeds the 700 GWP limit for new residential and light commercial equipment. Manufacturing of new R-410A equipment was prohibited under the AIM Act phasedown schedule.

R-410A Key Properties

R-410A operates at significantly higher pressures than R-22 — roughly 40-70% higher. That's why you can't use R-22 components with R-410A and vice versa.

If you're wondering how refrigerant charge amounts differ by type, we break it down in our charging guide. For system sizing context, check out the AC tonnage calculator.

R-454B (Opteon XL41): The Designated R-410A Replacement

R-454B is the big one. Developed by Chemours and marketed as "Opteon XL41" (Carrier sells it as "Puron Advance"), R-454B is a zeotropic blend of 68.9% R-32 and 31.1% R-1234yf. Most major manufacturers — Carrier, Trane, Lennox, Rheem, York — have selected R-454B as their primary R-410A replacement.

Its GWP of 466 represents a 78% reduction from R-410A. The performance (COP) is very similar to R-410A, though capacity is slightly lower — meaning R-454B coils may need 10-20% more heat transfer surface to match R-410A capacity in some applications.

R-454B Key Properties

The key difference technicians need to understand: R-454B is A2L (mildly flammable), unlike A1 R-410A. This means leak detectors rated for A2L refrigerants are required, along with enhanced ventilation protocols.

The good news? Both R-454B and R-410A use POE oil at ISO 32 viscosity, which simplifies the transition for oil handling. Because R-454B is zeotropic, it has a temperature glide of about 1.5°F — this affects how you calculate superheat and subcooling.

R-32: Lower-GWP Alternative for AC Systems

R-32 (difluoromethane) is a single-component refrigerant — not a blend — with a GWP of 675. Daikin has been the strongest advocate for R-32, using it in ductless mini-splits and residential systems across more than 100 countries. In the US market, Daikin selected R-32 over R-454B for many of its product lines.

R-32 offers some genuine advantages: higher energy efficiency (up to 12% better than R-410A in some configurations), lower refrigerant charge requirements, and simpler behavior as a pure compound (no temperature glide). The tradeoff is that R-32 produces higher compressor discharge temperatures because it lacks the R-125 component that acts as a flame suppressant in R-410A.

R-32 Key Properties

One critical detail: R-32 requires POE oil at ISO 46 viscosity — thicker than the ISO 32 used with R-410A and R-454B. That's because R-32 runs hotter without R-125 dampening discharge temperatures.

Using the wrong viscosity oil can lead to breakdown and compressor failure. For more on how refrigerant properties affect performance across temperature ranges, see our heat pump efficiency vs. temperature guide.

R-134a: Automotive and Commercial Refrigerant

R-134a (1,1,1,2-tetrafluoroethane) has been the workhorse automotive AC refrigerant since replacing R-12 in the mid-1990s. It's also widely used in medium-temperature commercial refrigeration and chillers. Its GWP of 1,430 and A1 safety class made it popular, but it's now being phased down in favor of R-1234yf in automotive applications.

R-134a Key Properties

In automotive applications, R-134a uses PAG oil (polyalkylene glycol) in standard vehicles. Hybrid and EV vehicles require POE oil because PAG is electrically conductive and could short-circuit the electric compressor. As of the current model year, over 95% of new US vehicles ship with R-1234yf instead of R-134a.

R-404A: Commercial Refrigeration Standard

R-404A is a blend of R-125 (44%), R-143a (52%), and R-134a (4%). It became the go-to refrigerant for supermarket display cases, walk-in coolers, cold storage, and other commercial refrigeration applications. Its GWP of 3,922 is the highest of any commonly used refrigerant — which is exactly why it's under the most regulatory pressure.

R-404A Key Properties

The commercial refrigeration sector is transitioning to lower-GWP HFO blends like R-448A (GWP 1,274) and R-449A (GWP 1,282) as near-drop-in replacements for R-404A. Many large supermarket chains are also moving to R-744 (CO₂) transcritical cascade systems for completely future-proof solutions.

R-407C: The R-22 Retrofit Replacement

R-407C is a blend of R-32 (23%), R-125 (25%), and R-134a (52%). It was specifically designed as a retrofit option for existing R-22 systems. Its operating pressures and capacity are similar enough to R-22 that it can work in many existing R-22 systems with modifications.

R-407C Key Properties

"Drop-in replacement" is a bit misleading here. R-407C requires an oil change from mineral oil to POE, and its zeotropic nature means it has significant temperature glide (~8°F).

You also need to adjust expansion devices. Still, it's the closest thing to a practical R-22 retrofit for commercial systems where full replacement isn't feasible.

R-290 (Propane): Natural Refrigerant With Excellent Properties

R-290 is propane — yes, the same propane from your grill. It has a GWP of just 3, zero ODP, and outstanding thermodynamic properties. Its energy efficiency is comparable to or better than R-410A in many applications.

R-290 Key Properties

The limiting factor is its A3 flammability classification. Charge limits for R-290 in occupied spaces are very restrictive — typically under 150 grams for indoor units.

That's enough for small self-contained systems like window units, portable ACs, commercial display cases, and monobloc heat pumps. But it's not practical for large ducted residential systems with their extensive line sets. For recharging window ACs, R-290 is becoming increasingly common.

R-744 (CO₂): Natural Refrigerant for Commercial Use

R-744 is carbon dioxide used as a refrigerant. With a GWP of 1 (by definition — it's the reference gas), zero ODP, and A1 safety classification, it's the ultimate "future-proof" refrigerant from a regulatory standpoint.

R-744 Key Properties

The challenge with R-744 is its extremely high operating pressures (up to 1,400+ psig in transcritical mode) and very low critical temperature of just 87.8°F. In warm climates, R-744 systems must operate above the critical point in a "transcritical" cycle, which adds complexity. Large supermarket chains are installing R-744 cascade and booster systems, but the technology requires specially rated equipment and trained technicians.

R-1234yf: Automotive R-134a Replacement

R-1234yf (2,3,3,3-tetrafluoropropene) is a hydrofluoroolefin (HFO) developed by Chemours and Honeywell as the automotive replacement for R-134a. With a GWP under 1 (AR6 value — lower than CO₂ itself), it delivers a massive environmental improvement over R-134a's GWP of 1,430.

R-1234yf Key Properties

R-1234yf is a near drop-in replacement for R-134a with very similar pressure-temperature characteristics. It requires specialized PAG YF oil (not standard PAG 46/100) and dedicated recovery/recycling equipment. It's also a key component of R-454B — making up 31.1% of that blend.

Refrigerant GWP Comparison Chart

Global Warming Potential or GWP measures how much heat one unit of a greenhouse gas traps relative to one unit of CO₂ over 100 years. A GWP of 2,088 (R-410A) means one pound of R-410A traps 2,088 times more heat than one pound of CO₂.

The IPCC calculates these values, and the EPA's AIM Act uses the IPCC AR4 (2007) GWP values as the regulatory baseline.

Here's what the GWP landscape looks like visually:

GWP Values by Refrigerant (100-year, AR4)

The contrast is striking. R-404A has a GWP nearly 4,000 times greater than R-744 (CO₂). Even the "new" standard R-454B is still 466 times more impactful than CO₂ on a per-pound basis — but that's a 78% improvement over R-410A, which is what the EPA is targeting.

Note: The EPA AIM Act's Technology Transitions Rule sets a GWP limit of ≤700 for new residential and light commercial AC/HP equipment. This is why R-454B (466) and R-32 (675) both qualify, while R-410A (2,088) does not.

Refrigerant Oil Compatibility Chart

Using the wrong oil with a refrigerant is one of the fastest ways to destroy a compressor. Each refrigerant requires a specific oil type that is miscible (can mix properly) with the refrigerant and provides adequate lubrication at operating temperatures.

Key takeaway for the R-410A → R-454B transition: both refrigerants use POE oil at ISO 32 viscosity, making the oil handling straightforward.

POE oil is highly hygroscopic — it absorbs moisture from the atmosphere rapidly. Always keep containers sealed and evacuate systems properly before charging.

The Refrigerant Transition: R-22 → R-410A → R-454B

We're in the middle of the third major refrigerant transition in HVAC history. Here's how each phase played out:

R-454B vs R-410A: Key Differences

R-32 vs R-410A

Here's the bottom line for homeowners: you cannot swap R-454B or R-32 into an existing R-410A system. The new refrigerants require equipment specifically designed for A2L safety compliance — different components, safety controls, and charge limits.

When your R-410A system reaches end of life, you'll replace the entire system with one designed for the new refrigerant. Your existing R-410A system can continue to be serviced with R-410A refrigerant for the remainder of its life.

For more on cooling issues related to refrigerant problems, see our guide on why your AC is not blowing cold air and AC short cycling causes.

Can You Mix Refrigerants?

No. Never. Under any circumstances.

Mixing refrigerants creates an unknown blend with unpredictable pressure-temperature behavior, unreliable superheat and subcooling readings, and potential chemical incompatibilities. It also violates EPA Section 608 regulations.

"Can you mix R-22 and R-407C?" No. "Can you mix R-410A and R-454B?" No. "Can you top off R-134a with R-1234yf?" No.

The system must be fully recovered, evacuated, and recharged with a single refrigerant type that matches the equipment nameplate.

What Refrigerant Does My AC Use?

Finding out which refrigerant your system uses is simple:

1. Check the nameplate. Every AC unit, heat pump, and refrigerator has a data plate (usually on the outdoor condenser unit, inside the indoor air handler cabinet, or on the back/side of a window unit). It lists the refrigerant type, charge amount, and other specs.
2. Check the service sticker. If a technician has serviced the system, there's often a sticker on the unit or near the disconnect showing the refrigerant type and charge.
3. Look at the age. As a general rule: systems manufactured before 2010 likely use R-22. Systems manufactured between 2010 and recent years almost certainly use R-410A. Systems manufactured under the AIM Act transition use R-454B or R-32.
4. Check the cylinder color. While cylinder colors are being standardized to light gray across the industry, older cylinders may still be color-coded: green (R-22), rose/pink (R-410A), light pink/orange (R-454B).

For details on how much refrigerant your specific system needs, check our AC refrigerant charge guide.

Frequently Asked Questions About Refrigerant Types

What are the 4 main types of refrigerant?

The four main categories are: CFCs (chlorofluorocarbons — like R-12, fully phased out), HCFCs (hydrochlorofluorocarbons — like R-22, phased out), HFCs (hydrofluorocarbons — like R-410A, R-32, R-134a, currently being phased down), and HFOs (hydrofluoroolefins — like R-1234yf, the newest generation with ultra-low GWP). Natural refrigerants (propane R-290, CO₂ R-744, ammonia R-717) form a fifth category that's gaining traction.

What refrigerant is replacing R-410A?

R-454B (marketed as Opteon XL41 by Chemours and Puron Advance by Carrier) is the primary replacement selected by most major US manufacturers including Carrier, Trane, Lennox, Rheem, and York. R-32 is the alternative chosen by Daikin and some other manufacturers, particularly for ductless mini-split systems.

Is R-454B flammable?

R-454B is classified as A2L (mildly flammable) under ASHRAE Standard 34. It has a low burning velocity of less than 3.9 inches per second, making it much harder to ignite than propane or natural gas. With proper installation per ASHRAE 15 and UL 60335-2-40 standards — including leak detection and ventilation — A2L systems are considered safe for residential use.

Can I put R-454B in my existing R-410A system?

No. Although R-454B operates at similar pressures to R-410A, the equipment must be specifically designed, certified, and listed for A2L refrigerants. A2L systems include leak detectors, modified electrical components, and safety controls that R-410A systems don't have. Charging an R-410A system with R-454B would void the warranty and violate EPA regulations.

Do I need to replace my R-410A system now?

No. Existing R-410A systems can continue to operate and be serviced for their remaining useful life. R-410A refrigerant will remain available for servicing, though it may become more expensive over time as production is phased down. When your current system reaches end of life and needs replacement, the new system will use R-454B or R-32.

What does GWP mean for refrigerants?

Global Warming Potential (GWP) measures how much heat a greenhouse gas traps in the atmosphere relative to CO₂ over 100 years. CO₂ has a GWP of 1 (the baseline). R-410A's GWP of 2,088 means one pound of R-410A has 2,088 times the warming effect of one pound of CO₂. The EPA uses GWP values from the IPCC's 4th Assessment Report (AR4, 2007) as the regulatory standard under the AIM Act.