R-515B PT Chart and Refrigerant Profile

Where you will find R-515B

R-515B, sold as Solstice N15, is an A1 azeotrope of R-1234ze(E) (91.1%) and R-227ea (8.9%). Honeywell’s data sheet describes it as a long-term replacement for R-134a in medium- and high-temperature applications. In HVAC that means chillers, heat pumps and high-ambient air conditioning; the same sheet lists supermarket systems, remote condensing units, the high-temperature side of cascade systems, flooded systems, stand-alone units and waterloop systems. Honeywell’s application guide also lists it against R-124.

The design idea is nonflammable R-1234ze(E). The small R-227ea share makes the blend A1, where R-1234ze(E) alone is A2L, and Honeywell says performance is nearly identical to R-1234ze(E). The computed charts agree: at 40°F R-515B reads 22.2 psig, the same as R-1234ze(E); at 100°F, 89.9 psig against 89.9 psig. Both run well below R-134a (35.1 psig at 40°F, 124.2 psig at 100°F). This page sits with the chiller refrigerants, but R-515B is not a vacuum refrigerant: it boils at -2.1°F and runs above atmospheric pressure in normal operation.

Charging R-515B

Honeywell lists zero glide, and the computed chart shows none, so the bubble and dew columns are identical. Suppliers recommend charging blends as liquid; an azeotrope barely fractionates, but liquid charging is the safe habit. Honeywell offers system-specific charging recommendations for new systems and says to optimize by proper charging and minimal running superheat. No numeric targets are given; charge to the chiller or system manufacturer’s data.

For field checks, use the superheat calculator on the suction side and the subcooling calculator on the liquid line, with targets from the nameplate or manual. Do not read R-515B against an R-134a chart: at the same temperature it runs roughly 13 psi lower at 40°F and 34 psi lower at 100°F.

Oil and compatibility

POE. Honeywell recommends polyol ester oil and says compressor makers qualify specific lubricants; BITZER lists POE only. Honeywell also advises against chlorinated solvents for cleaning, says compatible desiccant driers are commercially available (check with the drier maker), and asks retrofit users with chlorinated materials in the system to contact Honeywell.

Safety, handling and recovery

R-515B is A1 under ASHRAE 34: lower toxicity, no flame propagation. Honeywell notes that as an A1 refrigerant it is not subject to charge limit regulations or flame mitigation measures, and that storage and handling are similar to R-134a. That is the practical difference from R-1234ze(E), which needs A2L handling; see flammability safety classes.

Section 608: at 104°F R-515B saturates at 96.4 psig (111.1 psia), between 45 and 170 psia, so it is a medium-pressure refrigerant (40 CFR 82.152), the same class as R-134a. Work needs Type II or Universal certification. Required recovery levels for medium-pressure appliances (40 CFR 82.156 Table 1): 10 in Hg below 200 lb of charge, 15 in Hg at 200 lb or more. Venting is prohibited and sales are restricted to certified technicians since January 1, 2018 (40 CFR 82.154(c)).

Cylinders: AHRI Guideline N-2017 Table 1 assigns no legacy color to R-515B. New containers are light green-gray RAL 7044, with no red band because it is not flammable. Honeywell sells it in 100 lb and half-ton refillable cylinders. See cylinder colors.

Status and replacements

R-515B contains an HFC (R-227ea), so it counts under the AIM Act. GWP depends on the basis: 292 using the industry AR4 convention that Honeywell prints, 299 on AR5, and 287.5 on EPA’s 40 CFR 84.64 basis used for Technology Transitions (EPA’s SNAP chiller page lists 287).

Technology Transitions (40 CFR 84.54): at 287.5 it is below the 700 limit for new comfort-cooling and industrial process chillers, so it remains usable in new chillers. It exceeds the 150 limits that apply to sectors such as household refrigeration, stand-alone retail units, vending and ice machines.

SNAP: acceptable for new centrifugal chillers, positive displacement chillers and industrial process air conditioning (listed December 11, 2020), and for new supermarket systems, remote condensing units, refrigerated food processing and dispensing, commercial ice machines and cold storage warehouses (listed September 8, 2023). EPA’s listings are for new equipment.

From January 1, 2026 the HFC leak repair rule (40 CFR 84.106) applies to appliances with 15 lb or more of HFC or substitute with GWP above 53, which includes most R-515B chillers.

Other R-134a alternatives are compared on the R-134a replacement page, including R-513A and R-1234ze(E).

Common questions

What is the difference between R-515B and R-1234ze(E)?

Pressures are practically the same, but R-515B is A1 and R-1234ze(E) is A2L. R-515B has a GWP near 290 because of its R-227ea; R-1234ze(E) is an HFO outside the AIM Act phasedown.

What is the difference between R-515B and R-513A?

Both are A1 azeotropes offered as R-134a alternatives. R-513A runs close to R-134a pressures (39.8 psig at 40°F), while R-515B runs lower (22.2 psig at 40°F), so they are not interchangeable without the equipment maker’s approval.