R-454B (Puron Advance)
R-454B Line Set Calculator
Size the line set for an R-454B system and find out whether the existing R-410A set can stay. Sizing by tonnage and length, a REUSE, FLUSH, or REPLACE verdict, the charge adjustment, and a printable checklist. Every number cites a manufacturer source.
Reusing an R-410A Line Set with R-454B
R-454B is the A2L refrigerant that replaced R-410A in most new ducted equipment starting January 1, 2025. Because it uses the same POE oil and runs within about 5 percent of R-410A pressures, the line set rules are refreshingly simple: if the existing R-410A copper is the right diameter for the new system and it is sound and leak-free, it can be reused. There is no mineral-oil-to-POE flush to worry about, because that only applies when the old set held R-22.
The steps that do matter are the ones for any opened system: flush for cleanliness and purge with dry nitrogen, install a new liquid-line filter-drier rated at least 600 psig, pressure-test to roughly 150 psig with dry nitrogen, deep-evacuate to 500 microns, and weigh in the nameplate charge plus the line-length adjustment. Charge R-454B as liquid from an inverted cylinder so the R-32 and R-1234yf blend does not fractionate. Replace the set only when it is undersized, damaged, or over the length limit.
R-454B Line Set FAQs
Can I reuse my R-410A line set with R-454B?
Usually yes. If the liquid and suction diameters match what the R-454B system needs, the copper is sound and leak-free, and the run is within the length limit, you can reuse it. Flush and dry-nitrogen purge the set, install a new filter-drier rated 600 psig or higher, pressure-test and evacuate to 500 microns, and weigh in the charge. Both refrigerants use POE oil, so no oil-incompatibility flush is required.
What size line set does a 3 ton R-454B system use?
3/4 inch suction and 3/8 inch liquid up to about 25 feet, stepping the suction up to 7/8 inch past 25 feet. These match the R-410A sizes for 3 tons, which is why an existing 3 ton R-410A set usually fits an R-454B changeout.
Do I need to flush the line set going from R-410A to R-454B?
Not for oil reasons. R-410A and R-454B both use POE oil, so there is no mineral-oil-to-POE conflict like an R-22 changeover. Flushing is still recommended best practice for cleanliness (Bosch), while Carrier says the set can be reused without it. This calculator defaults to FLUSH and REUSE and notes that straight reuse is defensible.
Is an R-410A line set rated for R-454B pressures?
Yes. R-454B operates within about 5 percent of R-410A pressures, so copper rated for R-410A is pressure-adequate for R-454B. The component that must be rated higher is the new liquid-line filter-drier: use one rated at least 600 psig for A2L service.