R-448A
R-448A (Honeywell Solstice N40) is the main lower-GWP replacement for R-404A in U.S. commercial refrigeration. Its GWP of 1,386 sits under the 1,400 interim limit EPA set in May 2026 (91 FR 31284), which keeps it legal for new supermarket systems and remote condensing units through December 31, 2031[2].
EPA wrote the 1,400 interim limit around blends like R-448A, and the rule preamble names it directly[2]. The 2032 limits end that window for new installs. Existing R-448A systems stay legal to run and service.
R-448A quick facts
| ASHRAE safety class | A1 (no flame propagation)[9] |
| Type | HFC/HFO blend: 26% R-32, 26% R-125, 20% R-1234yf, 21% R-134a, 7% R-1234ze(E)[9] |
| GWP (AIM Act exchange values) | 1,386 (computed per 40 CFR 84.64, commonly published as 1,387)[1] |
| Temperature glide | About 7 °F. Bubble for charging, dew for superheat[7] |
| Lubricant | POE |
| Trade name | Honeywell Solstice N40 |
| Common use | R-404A retrofits and new commercial refrigeration under the interim limits |
Regulatory status
| Existing systems | Legal to run and service, no end date[2] |
| Bulk cylinders | Section 608-certified buyers only[3] |
| New supermarket and condensing-unit installsThe May 2026 rule set an interim GWP limit of 1,400 for these subsectors. R-448A's GWP of 1,386 passes it. | Allowed through Dec 31, 2031[2] |
| New cold storage installsCold storage warehouses carry an interim GWP limit of 700. R-448A's GWP of 1,386 is over it. | Not allowed since Jul 27, 2026[2] |
| R-404A retrofits (existing systems)A retrofit that raises system capacity by more than 15% counts as a new installation under the 2026 rule and must meet the new-install limits. | Allowed, per the manufacturer's retrofit bulletin[4] |
Rules
R-448A passes the 1,400 interim limit that covers retail food equipment and fails the 700 limit for cold storage. Federal rules set those limits by subsector, and several states set stricter ones[2].
Federal
The May 2026 reconsideration (91 FR 31284) moved the strict 150/300 limits to January 1, 2032 and set interim limits in the meantime[2].
| Subsector | Limit | Date | R-448A outcome |
|---|---|---|---|
| Supermarket systems | GWP 1,400 interim | Jan 1, 2027[2] | Qualifies until the GWP 150/300 limits arrive on Jan 1, 2032 |
| Remote condensing units (retail food) | GWP 1,400 interim | Jul 27, 2026[2] | Qualifies until the GWP 150/300 limits arrive on Jan 1, 2032 |
| Cold storage warehouses | GWP 700 interim | Jul 27, 2026[2] | Over the 700 limit, so not allowed for new cold storage systems |
| Industrial process refrigeration (non-chiller) | GWP 150/300 | Jan 1, 2026[4] | Over the 150/300 limits, in force since Jan 1, 2026 |
Five consolidated petitions challenge the May 2026 rule in the D.C. Circuit, filed by industry and environmental groups (lead case HARDI v. EPA, No. 26-1168)[2]. The interim limits that keep this refrigerant legal are part of what is being litigated. The dates above are current law while the litigation runs.
State
State rules can be stricter than the federal interim limits. Each row below is verified against the state's own regulation text:
| State | Rule | Effective |
|---|---|---|
| Washington | Retail food refrigeration over 50 lb charge (new): GWP over 150 prohibited, which covers R-448A | Jan 1, 2025 |
Washington prohibits refrigerants over GWP 150 in new retail food systems above 50 lb charge (WAC 173-443), so R-448A is not an option there even while federal interim limits allow it elsewhere[5]. Vermont (10 V.S.A. 586), Maryland, and Rhode Island restrict listed high-GWP substances in the same subsectors, and R-448A is not on those legacy lists. California's SB 1206 bulk sales thresholds reach GWP 750 in 2033, which would cover R-448A[6]. Verify with your local authority having jurisdiction before an install decision.
Buying R-448A
Bulk R-448A can only be sold to Section 608-certified technicians and a short list of related buyers under 40 CFR 82.154[3]. The blend is an HFC/HFO mix and carries the same purchase restriction as the HFCs it replaces.
Replacements
R-448A and R-449A are close siblings, and most equipment approved for one lists the other. For new equipment planned past 2031, the 2032 limits point to CO2, R-290, and A2L blends such as R-454C and R-455A[2].
R-448A PT chart
Saturation pressures for R-448A from -40 °F upward, computed from reference equations of state[7]. R-448A is a zeotropic blend with about 7 °F of glide, so the liquid and vapor columns differ. Use bubble pressure for charging and subcooling, and dew pressure for superheat.
| Temp (°F) | Liquid / bubble (psig) | Vapor / dew (psig) |
|---|---|---|
| -40 | 5.0 | -0.2 |
| -35 | 7.6 | 1.8 |
| -30 | 10.5 | 4.2 |
| -25 | 13.6 | 6.7 |
| -20 | 17.1 | 9.5 |
| -15 | 20.9 | 12.6 |
| -10 | 25.0 | 16.0 |
| -5 | 29.5 | 19.8 |
| 0 | 34.3 | 23.8 |
| 5 | 39.6 | 28.3 |
| 10 | 45.3 | 33.1 |
| 15 | 51.4 | 38.3 |
| 20 | 57.9 | 43.9 |
| 25 | 65.0 | 50.0 |
| 30 | 72.5 | 56.6 |
| 35 | 80.6 | 63.7 |
| 40 | 89.3 | 71.2 |
| 45 | 98.5 | 79.4 |
| 50 | 108.3 | 88.1 |
| 55 | 118.7 | 97.4 |
| 60 | 129.7 | 107.3 |
| 65 | 141.4 | 117.8 |
| 70 | 153.8 | 129.1 |
| 75 | 167.0 | 141.1 |
| 80 | 180.8 | 153.8 |
| 85 | 195.4 | 167.2 |
| 90 | 210.9 | 181.5 |
| 95 | 227.1 | 196.6 |
| 100 | 244.1 | 212.6 |
| 105 | 262.1 | 229.5 |
| 110 | 280.9 | 247.4 |
| 115 | 300.7 | 266.2 |
| 120 | 321.4 | 286.1 |
| 125 | 343.0 | 307.0 |
| 130 | 365.7 | 329.1 |
| 135 | 389.4 | 352.4 |
| 140 | 414.2 | 377.0 |
| 145 | 440.1 | 402.9 |
Use the vapor (dew) column to check superheat at the suction line. Use the liquid (bubble) column to check subcooling at the liquid line and for charging. R-448A glide is about 7 °F. Charging and subcooling read the bubble column. Superheat reads the dew column. R-448A values are computed, not transcribed; see Sources.
Equipment rated for R-448A
Walk-in unit cooler models whose maker publishes R-448A ratings. Each page shows the full specifications with the page each value comes from.
1,087 models in the database carry R-448A ratings. A sample:
Questions
- Can R-448A replace R-404A in an existing system?
Yes, and that retrofit is its main use. Expect a POE oil check, a TXV adjustment, and a reduced charge (Trenton documents specify a 0.96 factor relative to the printed R-404A charge). Follow the manufacturer's retrofit bulletin, and note that a capacity increase over 15% counts as a new installation under the 2026 rule. The R-404A to R-448A retrofit page lists affected models.
- What is the difference between R-448A and R-449A?
They are competing blends with near-identical GWP, capacity, and glide. R-448A is Honeywell Solstice N40 and R-449A is Chemours Opteon XP40. Equipment approvals usually list both, so match whichever your supplier stocks and the manufacturer lists.
- Can you mix R-404A and R-448A?
No. Mixing refrigerants creates a blend no PT chart or nameplate describes, and reclaimers reject contaminated charges. Recover the R-404A fully, then charge with R-448A per the retrofit bulletin.
References
- ^1.40 CFR part 84, Appendix A: GWP exchange values (eCFR)
- ^2.91 FR 31284 (May 26, 2026): Technology Transitions reconsideration final rule
- ^3.40 CFR 82.154: refrigerant sales restriction and venting exemptions (eCFR)
- ^4.88 FR 73098 (Oct 24, 2023): Technology Transitions final rule
- ^5.Chapter 173-443 WAC: Washington HFC regulation
- ^6.CARB HFC reduction program (SB 1206 overview) (accessed 2026-08-24)
- ^7.CoolProp 8.0 mixture models (Bell et al. 2014, doi:10.1021/ie4033999)
- ^8.40 CFR 84.7: HFC phasedown schedule (eCFR)
- ^9.ASHRAE refrigerant designations and safety classifications (Standard 34)
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