Refrigerant Retrofit Compatibility Calculator
Enter the existing refrigerant and the target replacement; the calculator evaluates compatibility across five criteria (lubricant, safety class, pressure, glide, application) and returns a verdict plus specific recommendations.
Updated October 25, 2026
R-22 → R-407C is feasible with an oil change. Drain existing lubricant, replace with POE, replace filter-drier, pull vacuum, charge by weight.
Per-criterion analysis
| Lubricant compatibility | ⚠Oil change required. R-22 uses MO/AB; R-407C uses POE. Drain existing oil, flush with new lubricant, change filter-drier. |
| Safety class transition | ✓Both are ASHRAE class A1. No safety-class-driven equipment changes required. |
| Pressure envelope | ⚠R-407C at 70°F = 140.5 PSIG vs R-22 121.4 PSIG (+15.7%). Pressure-rating verification required; some components may need replacement. |
| Temperature glide | ⚠R-22 is azeotropic; R-407C has 11.0°F glide. Existing TXV may not control superheat correctly across the glide range; expansion valve adjustment or replacement may be required. |
| Application family | ✓Both used in: Residential air conditioning; R-22 retrofit blends; Commercial refrigeration — medium temperature. Application overlap supports a realistic retrofit. |
Recommendations
- Recover all R-22 per EPA Section 608. Replace filter-drier with POE-compatible model.
- Oil change: drain MO/AB from the compressor and accessible low points; perform multiple complete POE oil changes or a triple flush; verify oil return at the compressor over the first weeks of operation.
- R-407C has 11.0°F temperature glide. Charge by weight per the system's calculated capacity (not by gauge). Use the dew curve for superheat math (the site's superheat calculator handles this automatically). TXV adjustment likely required.
- Pull vacuum to 500 microns; verify the vacuum holds for 30+ minutes before charging.
- Pressure verification: R-407C pressures differ from R-22 enough to warrant checking component ratings (compressor working pressure, line set rating, expansion valve setpoint).
- Verify cooling capacity output after retrofit; expect ~5-10% capacity change typical for HFC retrofit refrigerants.
The verdict is derived from the data layer (lubricants, safety class, composition, PT chart) plus the editorial comparison groups. It is decision-support, not a substitute for verifying the specific equipment OEM's approved refrigerant list before any retrofit work.
The retrofit decision — five questions, one verdict
A successful refrigerant retrofit requires the candidate refrigerant to satisfy five independent constraints simultaneously. Failing any one of them turns a simple swap into a partial retrofit, a partial retrofit into an equipment replacement, or an equipment replacement into a project that doesn't pay back.
Some verdicts are regulatory, not physical: EPA's SNAP program lists the A2L air-conditioning refrigerants (R-32, R-454B and the R-454 family) for new residential and light-commercial equipment only[1], and HFO-1234yf for new or newly manufactured vehicles under SAE J639[2] — so an existing A1 system can't be converted to them regardless of how the five criteria score.
- Lubricant compatibility. Does the existing oil family (mineral oil, AB, POE, PVE, PAG) work with the target refrigerant? Mineral oil works with R-22, hydrocarbons, and a few R-22 retrofit blends with hydrocarbon components.
- Safety classification transition. A1 → A1 (R-22 → R-407C): no equipment changes for safety. A1 → A2L (R-410A → R-454B): A2L equipment (A2L-listed equipment, IEC 60335-2-40 charge limits, leak detection in some jurisdictions). A → B (any HFC → R-717): not a retrofit, complete equipment replacement with ammonia-specific design.
- Pressure envelope. Within ±10% across operating range: retrofit-compatible. ±10-25%: standard retrofit (no component changes). ±25-40%: equipment-level review required (component pressure ratings, compressor capacity). >40%: not feasible without equipment redesign.
- Temperature glide. Pure → pure or pure → near-azeotrope: no service measurement change. Pure → wide-glide blend (R-22 → R-407C): TXV / EEV sensing-bulb tuning and PT chart curve selection awareness. Wide-glide → narrow-glide: less concerning but still a service procedure change.
- Application family. Residential AC, commercial MT refrigeration, commercial LT refrigeration, chiller, mobile AC — each category has its own design assumptions. Refrigerants engineered for one category rarely fit another (R-1234yf is for mobile AC; R-410A is for residential AC — no crossover).
The six verdict tiers — what each means
| Verdict | Criteria | Service procedure |
|---|---|---|
| Retrofit possible | All five OK | Recover, replace filter-drier, evacuate, recharge |
| Retrofit with oil change | Lubricant warn, others OK | + drain and replace lubricant |
| Retrofit with TXV / valve changes | Glide warn (pure → blend) | + retune TXV sensing bulb, verify metering compatibility |
| Equipment modifications required | Pressure warn 10-25%, safety class shift | Component pressure rating review, A2L compliance if applicable |
| Not recommended | Pressure fail 25-40%, ROI questionable | Evaluate full replacement instead |
| Not feasible | Application mismatch, pressure >40%, A→B class | Full equipment replacement only path |
AIM Act phase-down — the regulatory driver
The AIM Act (40 CFR Part 84) caps HFC production and import in the US on a declining schedule: 90% allocation in 2022, 60% in 2024, 30% in 2029, 15% in 2036. The phase-down forces transitions from high-GWP HFCs (R-410A, R-404A, R-134a) to lower-GWP A2L alternatives (R-32, R-454B, R-454C, R-1234yf). The retrofit compatibility analysis becomes increasingly important as the phase-down tightens supply and raises prices on the higher-GWP refrigerants.
| Sector | GWP cap | Compliance date | Affected refrigerants |
|---|---|---|---|
| Residential / light commercial AC | 700 | 2025-01-01 (new equipment) | R-410A out; R-32 / R-454B in |
| Commercial refrigeration (most subsectors) | Varies | 2025-01-01 (new equipment) | R-404A out; R-454C / R-455A / R-448A / R-449A in |
| Centrifugal chillers | Varies | 2025-01-01 | R-134a → R-513A / R-1233zd / R-1234ze |
| Mobile AC (passenger vehicles) | Varies | Restricted (new MVAC) | R-134a → R-1234yf (in production 2017+) |
The residential / light-commercial AC prohibition is the 700-GWP rule at 40 CFR 84.54(a)(1); limits differ by equipment type and subsector — see 40 CFR 84.54.
Real retrofit decision scenarios
Six pairs covering the most common retrofit decisions in 2025-2026: R-22 → various HFCs, R-410A → A2L, R-404A → low-GWP commercial, and the not-feasible cases (cross-sector and cross-class transitions).
R-22 to R-407C — the classic HFC retrofit
Scenario · Legacy R-22 residential AC, customer wants to extend equipment life rather than replace. R-407C is the most common HFC retrofit option for R-22 residential.
| Criterion | R-22 | R-407C | Verdict |
|---|---|---|---|
| Lubricant | MO / AB | POE | warn — oil change |
| Safety class | A1 | A1 | ok |
| Pressure @ 95°F | 181 PSIG | 215 / 180 bubble/dew | ok (within 20%) |
| Glide | 0°F | 11°F | warn — TXV awareness |
| Application | residential AC | residential AC | ok |
R-22 to R-422D — mineral-oil-compatible HFC blend
Scenario · Same R-22 system, but customer wants to avoid the oil change (older equipment with retro oil pickup, complex piping). R-422D is one of several HFC blends with hydrocarbon components specifically engineered for mineral-oil retention.
| Criterion | R-22 | R-422D | Verdict |
|---|---|---|---|
| Lubricant | MO / AB | MO / POE | ok |
| Safety class | A1 | A1 | ok |
| Pressure @ 95°F | 181 PSIG | 190 / 175 | ok (within 5%) |
| Glide | 0°F | 7°F | warn — minor TXV |
| Application | residential AC | residential AC retrofit | ok |
R-22 to R-410A — DON'T (the pressure delta makes this infeasible)
Scenario · Customer asks about retrofitting R-22 to R-410A directly. The pressure delta makes this a full equipment replacement, not a retrofit.
| Criterion | R-22 | R-410A | Verdict |
|---|---|---|---|
| Lubricant | MO / AB | POE | warn — oil change |
| Safety class | A1 | A1 | ok |
| Pressure @ 95°F | 182 PSIG | 296 PSIG | FAIL — +63% |
| Glide | 0°F | ~0°F (near-az) | ok |
| Application | residential AC | residential AC | ok |
R-410A to R-454B — A2L simple swap pressure-wise but A2L compliance required
Scenario · Existing R-410A residential AC. Customer asking about switching to R-454B for lower GWP. The pressure envelope matches almost perfectly, but A2L safety class shift requires equipment-level review.
| Criterion | R-410A | R-454B | Verdict |
|---|---|---|---|
| Lubricant | POE | POE | ok |
| Safety class | A1 | A2L | warn — lower flammability |
| Pressure @ 95°F | 296 PSIG | 280 / 270 | ok (within 6%) |
| Glide | ~0°F | 3°F | ok — minor |
| Application | residential AC | residential AC | ok |
R-404A to R-448A — commercial low-GWP retrofit
Scenario · Supermarket R-404A commercial refrigeration system. Under the AIM Act, new R-404A equipment is restricted across 40 CFR 84.54 categories by subsector and date (e.g. supermarket systems from January 1, 2027, 84.54(c)(12)(i)); for existing equipment, lower-GWP retrofit options include R-448A (Solstice N40) and R-449A (Opteon XP40).
| Criterion | R-404A | R-448A | Verdict |
|---|---|---|---|
| Lubricant | POE | POE | ok |
| Safety class | A1 | A1 | ok |
| Pressure @ 0°F evap | 28 PSIG | 27 / 21 | ok (within 5%) |
| Pressure @ 95°F cond | 232 PSIG | 245 / 222 | ok (within 5%) |
| Glide | ~1°F (near-az) | 6°F | warn — TXV awareness |
| Application | commercial refrigeration | commercial refrigeration | ok |
R-22 to R-717 — NOT FEASIBLE (cross-class, cross-application)
Scenario · Question that sometimes comes up: can we retrofit an R-22 system to ammonia? The answer is no — this is a fundamental class incompatibility.
| Criterion | R-22 | R-717 | Verdict |
|---|---|---|---|
| Lubricant | MO / AB | MO (steel) / PAO | warn |
| Safety class | A1 | B2L | FAIL — toxic |
| Pressure @ 95°F | 181 PSIG | 182 PSIG | ok by coincidence |
| Glide | 0°F | 0°F | ok |
| Material compatibility | Cu OK | Cu attacked | FAIL |
| Application | residential AC | industrial refrigeration | FAIL |
What this calculator does NOT evaluate
- Equipment-specific OEM compatibility. The calculator is pair-wise refrigerant analysis; equipment-specific compatibility depends on the specific compressor, expansion device, and control electronics. Always verify the OEM service literature for the specific equipment.
- Capacity match. Pressure envelope match does not guarantee capacity match. R-32 has ~10% higher volumetric capacity than R-410A even though pressures are similar; R-454C delivers slightly lower capacity than R-404A. Some retrofits require evaporator or condenser re-sizing.
- Local code compliance. A2L installations have charge limits, mechanical room ventilation requirements, and leak detection mandates that vary by jurisdiction. Check local code (IRC, IMC, state-specific amendments).
- Economic analysis. The calculator reports feasibility, not ROI. A feasible retrofit may not pay back vs replacement; an "equipment modifications required" verdict may be cheaper than full replacement for specific systems.
- Warranty implications.OEMs often void warranty if a non-approved refrigerant is charged into a system. The calculator doesn't check warranty terms — always verify with the OEM before retrofitting.
When to use this calculator vs the others
- Retrofit Compatibility (this page) — five-criterion pair analysis with structured verdict. Best for go/no-go decisions.
- PT Comparison Tool — visual pressure envelope check. Use before this calculator to screen candidates.
- Refrigerant Comparison Guide — long-form sourced reference for common HVAC refrigerant transitions.
- Per-pair pages — for popular comparisons (R-22 vs R-410A, R-32 vs R-410A, R-410A vs R-454B), dedicated pages walk through the transition with full sourcing.
- Per-refrigerant detail pages — every refrigerant has its own page documenting lubricants, safety class, pressures, and replacement options.
Primary sources
- [1]U.S. EPA, Fact Sheet — Final Rule 23: Protection of Stratospheric Ozone: New Listings for the Significant New Alternatives Policy Program. U.S. EPA. April 23, 2021. https://www.epa.gov/sites/default/files/2021-04/documents/fact_sheet_snap_final_rule_23_final_4-23-21_508.pdf (accessed October 25, 2026). Listing table, end use 'Residential and light commercial air conditioning and heat pumps (New)' — SNAP lists these A2Ls for new equipment only (R-32: same, excluding self-contained room air conditioners).
- [2]40 CFR Part 82, Subpart G, Appendix B (Acceptable Subject to Use Conditions), HFO-1234yf motor vehicle air conditioning. eCFR. current. https://www.ecfr.gov/current/title-40/chapter-I/subchapter-C/part-82/subpart-G/appendix-Appendix%20B%20to%20Subpart%20G%20of%20Part%2082 (accessed October 25, 2026). HFO-1234yf MVAC rows: every end use is new equipment or newly manufactured vehicles, under SAE J639 requirements — none covers retrofitting.
- ASHRAE Handbook—Refrigeration (2022) — lubricants, retrofit procedures, lubricant-refrigerant compatibility tables.
- ASHRAE Standard 34-2022 — refrigerant designation and safety classification (A1, A2L, A3, B1, B2L, B3).
- ASHRAE Standard 15-2022 — Safety Standard for Refrigeration Systems; machine room requirements, ventilation, leak detection.
- UL / IEC 60335-2-40 (2022) — A2L refrigerant charge limits, installation safety requirements.
- AIM Act (40 CFR Part 84) — HFC phase-down schedule, sector compliance dates, allowance allocations.
- EPA SNAP (40 CFR Part 82 Subpart G) — Significant New Alternatives Policy — refrigerant acceptability by end-use sector.
- IIAR Standards (IIAR 2, IIAR 9) — ammonia (R-717) installation and safety requirements.
- Manufacturer retrofit guides — Honeywell, Chemours, Arkema, equipment OEM retrofit bulletins for specific refrigerant transitions.
How to read your results
- Compatibility verdict
- The color-coded headline (green retrofit-possible through red not feasible) synthesizes all five criteria and weights the worst one — a single 'fail' produces a fail verdict no matter how well the other four align. Read the summary line beneath it for the one-sentence reason the pair landed in that tier.
- Lubricant compatibility
- Green means the two refrigerants share a compatible oil family, so no oil change is needed; amber means an oil change (drain, flush, new filter-drier) is required — typically mineral oil to POE when moving to an HFC; red means the lubricant systems are fundamentally incompatible, such as ammonia's steel-system oils versus HFC POE.
- Safety class transition
- Compares the two ASHRAE 34 classes. Green is the same class with no safety-driven changes; amber is a manageable shift or a downgrade in flammability; red is a blocking change such as A1 to A2L (needs A2L-rated electrical, refrigerant detection where the standard requires it, and charge limits per UL 60335-2-40) or any A-to-B cross-class move, which is not a swap at all.
- Pressure envelope
- Compares saturation pressure at 70°F between the two refrigerants and reports the percent change. Within ±10% is retrofit-compatible (green); ±10-25% is amber and requires verifying component pressure ratings; beyond ~25% is red — existing equipment is not rated for the higher pressures, so full replacement is the realistic path.
- Temperature glide
- Flags whether metering-device and superheat procedures change. Green when both refrigerants are pure or near-azeotropic, or both already glide; amber when moving from an azeotrope to a wide-glide blend, where the existing TXV may not control superheat across the glide range and may need adjustment or replacement.
- Application family
- Checks whether both refrigerants share an equipment category (residential AC, commercial refrigeration, chiller, mobile AC, and so on). Green means they overlap and a retrofit is plausible; red means they were engineered for different equipment types, whose compressor sizing and heat-exchanger geometry rarely swap successfully.
- Recommendations
- An ordered service procedure tailored to the issues detected — recovery per EPA Section 608, filter-drier and oil changes, pulling vacuum to 500 microns, glide and charge-by-weight notes, and post-retrofit capacity verification — or, for infeasible pairs, the case for full equipment replacement. A longer, more invasive list signals a harder retrofit.
How to use this calculator
- Pick the existing refrigerant in the system from the first dropdown. Defaults to R-22 (the most common retrofit-source refrigerant in current US practice).
- Pick the target replacement refrigerant from the second dropdown. Defaults to R-407C (a common R-22 retrofit option).
- Read the verdict at the top — color-coded from green (retrofit possible) to red (not feasible).
- Review the per-criterion table for the specific issues detected (lubricant mismatch, pressure exceeds rating, etc.).
- Follow the numbered recommendations for the actual service procedure.
Common errors
- Treating the calculator as authoritative for a specific piece of equipment — it's pair-wise refrigerant analysis, not equipment-specific compatibility. Always verify the OEM service literature for the specific equipment.
- Assuming 'retrofit possible' means no work required. Even simple-swap retrofits require recovery, filter-drier replacement, vacuum, and recharge per EPA Section 608 — they just don't require oil change or equipment modifications.
- Ignoring the verdict's specific reasoning in favor of the headline. 'Not recommended (pressure)' tells you a different story than 'Not feasible (lubricant incompatible)'.
Underlying math
Formula
verdict = synthesize(lubricantCheck, safetyClassCheck, pressureCheck, glideCheck, applicationCheck) Each check has severity ∈ {ok, warn, fail}. The synthesis prioritizes fails (application > safety > pressure > lubricant) and then collapses warns into 'retrofit with modifications' verdicts.
Source
Lubricant compatibility: refrigerant.lubricants.compatible arrays from manufacturer datasheets and ASHRAE Handbook—Refrigeration (2022). Safety class transitions: UL 60335-2-40 (A2L charge limits), ASHRAE Standard 15 (machine room ventilation), ASHRAE 34-2022 (classification definitions). Pressure thresholds (10%, 25%) reflect typical equipment pressure-rating margins per manufacturer service literature. Application family memberships: editorial groupings in src/data/comparison-groups.ts.
Worked example
R-22 → R-407C: Lubricant: MO/AB vs POE — different families, oil change required (warn) Safety: A1 → A1 unchanged (ok) Pressure: 121.4 PSIG vs 140.5 / 117.3 PSIG at 70°F — within 10% (ok) Glide: pure → 23 PSI bubble–dew spread blend — TXV concern (warn) Application: both in residential-ac group (ok) Verdict: 'Retrofit with oil change' — proceed with standard HFC retrofit procedure. R-22 → R-410A: Lubricant: MO/AB vs POE — oil change required (warn) Safety: A1 → A1 unchanged (ok) Pressure: 121.4 PSIG vs 201.5 PSIG at 70°F — +66% (fail) Glide: pure → near-azeotrope (ok) Application: both residential-ac (ok) Verdict: 'Not recommended (pressure)' — equipment not rated for R-410A pressures; full system replacement.
Related tools
Frequently asked
›How is the compatibility verdict computed?
The calculator evaluates five criteria from the data layer: (1) lubricant compatibility — does the intersection of existing and target lubricants include anything? (2) safety class transition — A1 to A2L requires equipment changes; A to B is essentially impossible. (3) Pressure envelope — pressures within 10% are OK; 10-25% requires verification; over 25% requires equipment-level changes. (4) Temperature glide — pure to high-glide blend may require TXV adjustment. (5) Application family — refrigerants in different application groups rarely swap successfully. The overall verdict synthesizes these into one of six categories from 'retrofit possible' to 'not feasible'.
›What does 'retrofit possible' mean?
Same lubricant family, same safety class, pressures within 10%, similar glide character, and shared application family. A simple swap still means following standard retrofit procedure (recover, replace filter-drier, pull vacuum, charge by weight) but doesn't require oil change, equipment modifications, or component upgrades. The R-22 retrofit family (R-417A, R-422D, R-427A, R-438A) achieves this designation by having mineral-oil compatibility plus pressures similar to R-22.
›Why does R-22 to R-410A return 'not recommended' instead of 'equipment modifications required'?
Because R-410A's pressures are roughly 60-65% higher than R-22's — exceeding the pressure ratings of R-22 system components by a margin that makes component replacement (essentially the whole system) more expensive than a new R-410A system. The verdict reflects field reality: R-22 to R-410A is full equipment replacement, not retrofit, in nearly every case.
›Can I use this for residential AC retrofit planning?
Yes for the structural decision (whether retrofit is feasible) but consult equipment OEM service literature for the specific equipment's approved refrigerant list. The calculator's analysis is generic to the refrigerant pair; equipment-specific compatibility depends on the specific compressor, expansion device, and electrical components that the OEM has certified for each refrigerant.
›Why is ammonia retrofit always 'not feasible'?
B-class refrigerants (B1, B2L) use purpose-built equipment systems incompatible with A-class HVAC. Ammonia uses steel piping (it attacks copper), specific lubricants (mineral oil or PAO, never POE), specialized safety equipment (IIAR-rated machine rooms, ammonia-specific leak detection, full-face SCBA for service), and refrigerant-specific compressor designs. No refrigerant-swap retrofit between ammonia and any other refrigerant is realistic; new installations are designed from scratch as ammonia or non-ammonia systems.
›What about CO2 (R-744) retrofit?
Also generally not feasible as a refrigerant swap. R-744 systems operate at very high pressures (transcritical above ~1300 PSIG high-side), use specific CO2-rated POE lubricants, and have purpose-built component pressure ratings (typically 130 bar / ~1900 PSIG). There is no meaningful refrigerant-swap path from HFC systems to R-744; the realistic transition is full equipment replacement with CO2 transcritical equipment at end of equipment life.
›Why use this calculator instead of just reading the per-refrigerant pages?
Per-refrigerant pages document each refrigerant in isolation; this calculator evaluates the specific pair-wise decision. The structural questions (same lubricant? same safety class? compatible pressures? acceptable glide change? matching application?) require comparing two records simultaneously — which is what the calculator does automatically. For one-off retrofit questions, the calculator is faster than cross-referencing two refrigerant pages.