R-32 (A2L)
R-32 Line Set Calculator
Size an R-32 line set by tonnage and length, get the per-foot charge adjustment, and check whether an existing R-410A set can be reused. Because R-32 moves less mass than R-410A, the tool surfaces the tube-velocity caution that a straight diameter match would miss.
R-32 and the Tube-Velocity Catch
R-32 is a single-component A2L refrigerant common in mini-splits and a growing number of ducted systems. It shares the residential tubing table with R-410A, so the nominal liquid and suction diameters for a given tonnage are the same. The difference that matters for line sets is mass flow: R-32 moves less refrigerant mass than R-410A at the same capacity, which means lower velocity in the same pipe. Low velocity is the enemy of oil return, especially on long runs and vertical risers.
That is why Goodman's R-32 documentation explicitly warns against reusing existing R-410A tubing without evaluating tube velocities across the operating range. A set that was fine for R-410A can run too slow on R-32 and pool oil in the evaporator. When the diameters match the R-32 table and the run is not excessively long, reuse is fine after the usual flush, new 600+ psig drier, leak test, and 500 micron evacuation. When in doubt on a long or oversized set, size fresh copper to the table rather than assume the old set transfers.
R-32 Line Set FAQs
Can I reuse an R-410A line set with R-32?
With caution. R-32 uses POE oil like R-410A, so oil is not the barrier, but R-32 moves less mass and runs lower velocities in the same tube. Goodman's R-32 guidance says not to reuse existing R-410A tubing without evaluating tube velocities across the operating range. If the diameters match the R-32 table and velocities check out, flush and reuse it with a new drier, leak test, and evacuation.
What size line set for a 2 ton R-32 system?
5/8 inch suction and 1/4 inch liquid up to about 24 feet, then 3/4 inch suction and 3/8 inch liquid from 25 to 79 feet. R-32 uses the same residential tubing table as R-410A; the difference shows up in velocity and charge, not the nominal diameters.
How much charge does an R-32 line set add?
R-32 adds between 0.23 and 0.64 oz per foot beyond the 15 foot base, depending on the suction and liquid combination (Goodman IOG-4047, p.9). For example, a 3/4 inch suction with 3/8 inch liquid adds 0.55 oz per foot. The calculator applies the exact combination automatically.
Does R-32 need a bigger line set than R-410A?
No, the nominal diameters are the same for a given tonnage. The catch is velocity: because R-32 moves less refrigerant mass, an oversized or long R-410A set can run velocities too low for good oil return. That is why reusing R-410A tubing for R-32 calls for a velocity check rather than a straight diameter match.