What can replace R-22 in an existing system?

Why retrofit exists at all

With new R-22 equipment prohibited since 1 January 2025 and virgin supply on a declining quota, owners of serviceable plant face a three-way choice: keep buying R-22 while economics allow, retrofit to an HFC blend, or replace the equipment. Retrofit blends were engineered to approximate R-22's pressure-temperature behaviour closely enough that the compressor, coils and much of the pipework survive — a mid-life option that defers capital.

The candidates compared

The oil column is the real decision driver: mineral oil does not circulate with HFCs (mechanism in the oil guide), so a "cheap" blend that forces a full POE flush can cost more than a dearer blend that tolerates the existing charge.

The non-negotiables

Every manufacturer bulletin and the US EPA's retrofit guidance agree on the same rules. Recover first: retrofit blends must never top up remaining R-22 — the result is an unspecified mixture with unpredictable pressures (see mixing). Charge as liquid: all these are zeotropic blends; vapour charging fractionates the composition. Relabel: the system must be marked with its new refrigerant and oil so the next technician is not working blind. Check elastomers and the expansion device: seals and TXV settings tuned for R-22 may need attention.

The honest economics

Retrofitting buys years, not decades: a converted system typically gives up a few percent of capacity or efficiency, and the blends themselves carry ~1,800–2,100 GWPs that Kigali will squeeze after 2028. For plant with real remaining life, that trade is often excellent; for tired equipment, replacement with R-32-class kit usually wins on lifecycle cost. Where a system stays on R-22, buy the shrinking supply only through registered sellers — we stock R-22 for servicing alongside the HFC lines retrofits draw on.

A retrofit walkthrough, and when to refuse the job

The competent sequence, condensed from manufacturer bulletins: (1) Baseline — record operating pressures, superheat/subcool, amp draw on R-22, because 'is the retrofit performing?' is unanswerable without a before. (2) Recover completely — to specification vacuum, no shortcuts; residual R-22 contaminates the new charge (why). (3) Oil decision — R-407C path: flush mineral oil to low residual over multiple cycles and charge POE; R-438A/R-427A path: existing oil usually stays (the entire point of those blends). (4) Consumables — new filter-drier always; inspect seals/elastomers; verify the expansion device suits the new fluid. (5) Evacuate deep, charge as liquid — all retrofit blends are zeotropes (glide rules). (6) Commission against baseline and relabel — gas, oil, date, on the unit. Just as important is the refusal list, because some retrofits are money burnt: compressors near end-of-life (the retrofit outlives nothing), systems with chronic leak histories (new gas exits the same holes), heavily burnt-out circuits (acid contamination survives the gas swap), and undersized applications already struggling on R-22 (a few percent capacity loss lands hardest there). For that tier, redirect the budget toward R-32-generation replacement and keep the remaining R-22 fleet honest instead — triage logic in the availability guide.

Related: R-22 servicing supply · Mineral vs POE oil · Phase-out timeline