R-454C vs R-290 for new grocery refrigeration cases

R-454C is an HFO/HFC blend (R-32 + R-1234yf), GWP 148, ASHRAE A2L safety classification (mildly flammable, low toxicity). It runs in larger systems with charges up to 100+ lbs per circuit subject to building code limits. R-290 is propane, GWP 3, ASHRAE A3 (highly flammable, low toxicity). Charge per circuit is sharply limited — typically under 500 grams (1.1 lb) for retail spaces — which forces a self-contained per-case architecture.

Under ASHRAE 15-2022 and the 2023 Florida Building Code's adopted provisions, R-454C as A2L can be installed in occupied retail spaces at charges up to roughly 26 lbs per circuit without specialized ventilation requirements, scaling higher with engineered ventilation. R-290 charge in retail public-occupied space is limited to approximately 150-500 grams per circuit depending on application class. This is the central architectural fork: R-454C lets you keep distributed or larger-circuit systems; R-290 forces self-contained per-case.

R-290 has slightly better thermodynamic efficiency than R-454C in low-temp applications — typically 5-10% lower energy consumption on equivalently-sized cases. R-454C and R-290 are roughly comparable in medium-temp applications, with the architecture (self-contained vs distributed) often having more impact on total store energy than the refrigerant choice itself.

R-454C service is closer to existing R-448A practice — same general tooling, same recovery procedures, same cylinder handling. Existing EPA 608 certification covers it. R-290 service requires specialized training: hydrocarbon-safe recovery equipment, brazing only with the system fully evacuated, ignition-source management at the work area. Most supermarket techs in Tampa Bay can service R-454C with their current toolkit; R-290 requires deliberate training investment.

Refrigerant cost: R-290 is dramatically cheaper than R-454C per pound, but charges are so small per case that bulk consumption is low either way.

A leak on a self-contained R-290 case at typical charge of 150-300 grams puts the leaked refrigerant below the lower flammability limit (LFL) in any reasonable retail space within seconds — which is exactly why the codes allow R-290 in occupied retail at small charges. A leak on a 50-lb R-454C distributed circuit is a much bigger event; the code response is engineered ventilation, leak detection with auto-shutoff, and ignition-source separation in the equipment area.

New centralized parallel rack or distributed-system installs at any store size above ~30,000 sq ft generally make sense on R-454C. Existing rack architectures being upgraded in place benefit from R-454C's similarity to R-448A service practices. Stores planning future expansion into prepared-foods kitchens or high-volume deli operations benefit from the larger circuit capacity R-454C allows.

New small-format and convenience-grocery formats under 20,000 sq ft are usually best on R-290 self-contained throughout. Existing stores doing case-by-case replacement during remodel cycles often choose R-290 self-contained per case, which avoids touching the rack at all. Operators with strong building-management programs and tech training capability find R-290's per-case simplicity easier to operate at scale than centralized systems of any refrigerant.

Most large Tampa Bay grocery operators in 2026 will run a mixed strategy: legacy R-448A racks operating in service for 5-10 more years, new R-454C distributed systems on remodels and new builds, and R-290 self-contained on case-by-case replacements at end of life. This is fine — the AIM Act §103 doesn't require uniformity across a store, only that new equipment installed after January 2027 meets GWP-150.