Refrigerant Transition: R-410A to R-32 and R-454B
What You Need to Know
R-410A is on the way out. Australia's HFC phasedown, driven by the Kigali Amendment to the Montreal Protocol, cuts the amount of high-GWP refrigerant the country can import each year. Two lower-GWP replacements now lead the market: R-32 (GWP 675) for split systems and R-454B (GWP 466) for ducted and packaged units. Both are A2L (mildly flammable), which means new tools, new training, and new charge limit rules under AS/NZS 5149.
The Rules
- Australia's HFC import quota sits at 4.25 million tonnes CO2-e for 2026–27, roughly half the 2018 baseline. It drops to 85% below baseline by 2036 (Kigali Amendment / Ozone Protection and Synthetic Greenhouse Gas Management Act 1989)
- All refrigeration systems and heat pumps must comply with AS/NZS 5149 Parts 1–4 for design, construction, installation, and safety (NCC 2025, referenced standard)
- R-32 and R-454B are classified A2L (mildly flammable) under AS/NZS ISO 817:2016. They are Dangerous Goods Class 2.1 for transport (AS/NZS ISO 817:2016)
- Maximum refrigerant charge in residential and light commercial systems must follow the manufacturer's charge limit table. The minimum floor area depends on charge size, room height, and ventilation (AS/NZS 60335.2.40:2025)
- Charge limits for larger commercial systems follow Annex A, based on refrigerant flammability class and room occupancy type (AS/NZS 5149.1:2016 Amd 2:2018)
- A refrigerant handling licence (RHL) is required to work on R-32 or R-454B systems. A refrigerant trading authorisation (RTA) is required to buy, hold, or dispose of these refrigerants (Ozone Protection and Synthetic Greenhouse Gas Management Act 1989)
What This Means in Practice
R-410A is not banned outright. Existing systems can keep running, and service refrigerant remains available. But supply is shrinking. Each two-year quota period tightens the cap, pushing prices up and availability down. New projects should specify R-32 or R-454B now to avoid locking in a refrigerant with a closing supply window.
R-32 suits split systems well. It is a pure substance with no temperature glide, runs at pressures close to R-410A, and delivers about 10% more cooling capacity per unit of charge. Most Asian-manufactured splits (Daikin, Mitsubishi, Fujitsu) already ship with R-32. The trade-off: discharge temperatures run 10–15°C hotter than R-410A, so compressor cooling matters more.
R-454B is a blend of 68.9% R-32 and 31.1% R-1234yf. It has a lower GWP (466 vs 675) and operating pressures about 5% below R-410A, which eases compressor stress. It suits ducted and packaged equipment where US-based manufacturers (Carrier, Trane) have standardised on it. The catch: it has a small temperature glide (1.0–1.3 K), so it must be charged in liquid phase only.
Both refrigerants are A2L, so the old toolbox does not work. Manifolds, gauges, vacuum pumps, and recovery units must all be rated for A2L/A2 use. Recovery cylinders must be A2L-specific with the correct pressure rating. Standard A1-rated equipment is not compatible.
Key Design Decisions
R-32 or R-454B?
Pick R-32 for split systems (VRF, wall-hung, cassette). Pick R-454B for ducted or packaged rooftop units where the equipment manufacturer has standardised on it. Do not mix refrigerant types across a project without good reason.
Charge Limits and Room Sizing
For residential and light commercial, follow the manufacturer's charge limit table in the installation manual. The minimum floor area depends on charge size, unit height, room ventilation, and any risk mitigation devices fitted (AS/NZS 60335.2.40). For larger commercial systems, calculate against AS/NZS 5149.1 Annex A using the room occupancy class and A2L flammability data.
Plant Room Ventilation for A2L
Enclosed plant rooms with A2L equipment need ventilation sized for the full refrigerant charge in a worst-case leak. AS/NZS 5149.3 sets the rules for plant room classification and ventilation rates. A leak detector tied to the ventilation system is the standard approach.
Keep or Replace Existing R-410A Systems?
Run existing R-410A systems to the end of their service life. Do not retrofit R-32 or R-454B into R-410A equipment. The compressor oil, expansion device, and safety controls are not compatible. When replacement time comes, specify the new refrigerant and budget for A2L-compliant installation.
Who Needs to Know What
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References
- Montreal Protocol, Kigali Amendment (2016), HFC phasedown schedule for developed countries
- Ozone Protection and Synthetic Greenhouse Gas Management Act 1989 (Cth), as amended
- AS/NZS 5149.1:2016 Amd 2:2018, Refrigerating systems and heat pumps - Safety and environmental requirements - Part 1: Definitions, classification and selection criteria
- AS/NZS 5149.2:2016, Refrigerating systems and heat pumps — Safety and environmental requirements — Part 2: Design, construction, testing, marking and documentation
- AS/NZS 5149.3:2016, Refrigerating systems and heat pumps — Safety and environmental requirements — Part 3: Installation site
- AS/NZS 5149.4:2016, Refrigerating systems and heat pumps — Safety and environmental requirements — Part 4: Operation, maintenance, repair and recovery
- AS/NZS 60335.2.40:2025, Household and similar electrical appliances — Safety — Particular requirements for electrical heat pumps, air-conditioners and dehumidifiers
- AS/NZS ISO 817:2016, Refrigerants - Designation and safety classification
- National Construction Code 2022, Volume One (references AS/NZS 5149 Parts 1–4)
- Refrigerant Handling Code of Practice 2025 Edition (ARC/AIRAH), Parts 1 and 2
- DCCEEW, Australia's HFC Phase-Down Factsheet