R-410A vs. R-454B and your line set
Short answer: In 2026, mini-splits are switching from R-410A to the lower-GWP R-454B, a mildly flammable A2L refrigerant. For your line set the copper you run is essentially the same: same sizing and same install. The differences are at the equipment level, not in the pipe. Just match the line set and system to the same refrigerant.
2026 is the year mini-splits switch refrigerants. If you're buying a system or a line set right now, here's what the change from R-410A to R-454B actually means — and the good news for line sets: the copper you run is essentially the same either way.
Why the change
R-410A has a high global warming potential (GWP) — about 2,088. Under the U.S. AIM Act, regulators are phasing high-GWP refrigerants out of new equipment, so manufacturers moved to lower-GWP A2L refrigerants. Most chose R-454B, which has a GWP around 466 — roughly 78% lower — while Daikin went with R-32. New systems generally ship on the new refrigerants from January 1, 2026.
What it means for the line set
Here's the part that matters for buying a line set: a line set is just insulated ACR copper. R-454B runs at pressures very close to R-410A and uses the same POE oil, so the line set hardware doesn't change. A correctly sized, properly rated copper line set works with an R-410A or an R-454B system — the refrigerant lives in the system and the charge, not in the type of tubing you buy.
In other words: you don't need a special "R-454B line set." You need the right diameter for your unit and the right length for your run. Use our size calculator or size chart to get that right, and confirm against your manual.
What is different: tools and handling
The change shows up in service, not in the copper. Because R-454B is A2L (mildly flammable), your gauges, recovery equipment, and leak detector should be A2L-rated, and charging and service follow A2L procedures and local code. None of that changes the line set you install — it changes how a technician charges and services the system. Match your tools and any added charge to your unit's refrigerant.
Can you reuse an R-410A line set with R-454B?
For a brand-new install, this doesn't come up — you run a new line set anyway. The question matters when replacing a system on existing copper. Because both refrigerants share POE oil and similar pressures, the copper is generally compatible, but old lines can hold residual oil, moisture, or debris. Follow the manufacturer's changeout procedure — many require flushing the lines or replacing them outright, and skipping that can contaminate the new system. When in doubt, a fresh line set removes the risk.
Refrigerant by brand
| Brand | Refrigerant |
|---|---|
| MRCOOL | R-410A (older) → R-454B (newer DIY) |
| Pioneer | R-410A → R-454B |
| Mitsubishi | R-410A → R-454B (GX-Series) |
| Daikin | R-32 (Aurora), older R-410A |
| Fujitsu | R-410A → R-454B (AIRSTAGE) |
| Senville & Cooper & Hunter | R-410A → R-454B |
Daikin is the notable exception — it standardized on R-32 rather than R-454B. Either way, the line set you buy is the same copper; only the refrigerant and the service tools differ.
Bottom line
The 2026 refrigerant change is a big deal for equipment and for technicians' tools — but a small one for line sets. Buy the correct line set diameter and length for your system, match your gauges and charge to its refrigerant, and follow the manual. If you're choosing a system, the refrigerant is one factor among efficiency, climate, and install type.
Common questions
What is R-454B?
R-454B is a next-generation refrigerant replacing R-410A in most new mini-splits as of 2026. It has a much lower global warming potential (around 466 versus about 2,088 for R-410A — roughly 78% lower) and is classified A2L, meaning mildly flammable. It runs at pressures close to R-410A and uses the same POE oil, so the copper line set hardware is fundamentally the same.
Is R-454B compatible with R-410A line sets?
The copper line set itself is compatible — both refrigerants use POE oil and run at similar pressures, so a properly rated line set works with either. The difference is in handling, tools, and the system, not the tubing. For a new install you use a new line set sized to your run. For converting an existing system, follow the manufacturer's changeout procedure, which may require flushing or replacing the lines.
Do I need a special line set for R-454B?
No special line set is required — a standard ACR copper line set in the correct diameter works with R-410A or R-454B systems, because the line set is just insulated copper. What must match your refrigerant are the gauges, leak detector, and any charge you add. Always size the line set to your unit and confirm against the manual.
Why did mini-splits switch to R-454B?
R-410A has a high global warming potential, so U.S. regulations under the AIM Act phase it out of new equipment. Manufacturers moved to lower-GWP A2L refrigerants — most to R-454B, and Daikin to R-32 — with new systems generally shipping on the new refrigerants from January 1, 2026.
Is R-454B flammable or dangerous?
R-454B is classified A2L, which means mildly flammable — far less flammable than propane-type refrigerants, but not non-flammable like R-410A. In practice it requires A2L-rated tools, leak detection, and handling per the manufacturer and code. The copper line set itself carries no extra risk; the precautions apply to charging and service.
This guide is general information, not a substitute for your unit's installation manual or a licensed professional. Refrigerant handling in the United States requires EPA Section 608 certification, and A2L refrigerants have specific service requirements. Confirm refrigerant type, line set compatibility, and changeout procedures with your manufacturer and local code before installing.