R-22 vs R-32: Two Generations of Residential AC Refrigerant
R-22 is the legacy HCFC residential AC refrigerant (banned for production 2020); R-32 is the modern A2L HFC replacement. Different lubricants (MO vs POE), different safety classes (A1 vs A2L), different pressure envelopes (R-32 ~70% higher). Full equipment replacement is the only path.
PT curves, overlaid
Both refrigerants are pure or near-azeotropic — single curve per series.
Pressure comparison at service temperatures
Side-by-side pressure values at common service temperatures, computed from CoolProp 7.2.0. Useful for retrofit feasibility — pressure deltas within ±20% typically allow drop-in compatible service equipment; larger deltas require component pressure-rating review.
| Temperature | R-22 | R-32 | Δ vs R-22 |
|---|---|---|---|
| -20°F | 10 PSIG | 27 PSIG | +162.6% |
| 0°F | 24 PSIG | 49 PSIG | +105.0% |
| 40°F | 69 PSIG | 121 PSIG | +76.4% |
| 70°F | 121 PSIG | 206 PSIG | +69.5% |
| 95°F | 182 PSIG | 303 PSIG | +66.6% |
| 120°F | 260 PSIG | 429 PSIG | +65.2% |
Pressure delta visualization: positive = R-32 runs higher than R-22; negative = lower. Service equipment pressure rating matters when delta exceeds ±20% on the discharge side. For R-22 (zeotropic blend) bubble pressure is shown; for R-32 same rule applies.
Property differences side by side
- Safety class change: R-22 (A1) → R-32 (A2L). A2L equipment requirements apply: sealed motors, charge limits, leak detection per IEC 60335-2-40.
- GWP impact: R-22 = 1,810, R-32 = 675 (-63% vs R-22). Switching reduces direct climate impact substantially.
- Lubricant: R-22: MO/AB; R-32: POE. Retrofit requires oil change (mineral oil to POE).
- AIM Act status: R-32 is affected by AIM Act phase-down; the other is not. Drives new-equipment specification decisions in US market.
Properties side by side
| Property | R-22 | R-32 |
|---|---|---|
| Type | hcfc | hfc pure |
| ASHRAE class | A1 | A2L |
| Composition | Pure | Pure |
| GWP (AR5) | 1810 | 675 |
| ODP | 0.055 | 0 |
| Lubricant | MO, AB | POE |
| Boiling point @ 1 atm | -40.8°C | -51.6°C |
| Critical point | 96.2°C / 709 PSIG | 78.1°C / 824 PSIG |
| Temp glide | 0.00°F | 0.00°F |
| AIM Act affected | No | Yes |
Choose R-22 if…
Servicing existing R-22 equipment with original R-22. Reclaimed R-22 remains legal under EPA rules. Equipment design and lubricant stay matched to original specification. The trade-off is rising refrigerant cost as reclaim supply shrinks.
Choose R-32 if…
New residential AC equipment installations in markets where R-32 (vs R-454B) is the OEM choice. R-32 is a pure refrigerant (no glide, no fractionation concern), GWP 675 (below AIM Act 700-GWP threshold), and offers higher volumetric capacity than R-22 or R-410A. Daikin, Mitsubishi, and LG lead with R-32; Carrier/Trane/Lennox tend toward R-454B.
When neither is ideal
For existing R-22 equipment needing significant work, R-22 retrofit blends (R-407C, R-422D, R-438A) buy time without equipment replacement — but those are HFC blends facing their own AIM Act phase-down. For maximum future-proofing, full equipment replacement with new R-32 or R-454B is the durable answer.
Retrofit and transition
R-22 to R-32 is NOT a retrofit — it requires full equipment replacement. Four structural blockers:
1. **Safety class change (A1 → A2L).** R-22 equipment is A1-rated (non-flammable refrigerant); R-32 is A2L (mildly flammable). The change requires sealed-motor design, A2L-rated leak detection sensors, charge limits per UL 60335-2-40 / IEC 60335-2-40, ignition-source isolation in the refrigerant circuit. Retrofitting an A1-rated chassis to A2L is not permitted under most codes and voids OEM warranty.
2. **Pressure envelope mismatch.** R-32 operates at approximately 70% higher pressures than R-22 across the operating envelope. At 95°F outdoor ambient, R-22 saturation is ~181 PSIG vs R-32 ~296 PSIG. R-22-rated components (condenser, line set, expansion device, compressor) are not pressure-rated for R-32 operation.
3. **Lubricant incompatibility.** R-22 uses mineral oil (MO); R-32 requires polyolester (POE) oil. The two lubricant classes are chemically incompatible; mixing produces sludge and accelerated component wear.
4. **Compressor sizing.** R-32's higher volumetric capacity means an R-32-optimized system uses a smaller compressor displacement than an R-22 system of the same cooling capacity. An R-22 compressor running R-32 would be oversized for the load, producing short-cycling and discomfort.
For systems where R-22 service is no longer viable: full system replacement with R-32 or R-454B equipment is the path. New equipment typically delivers 20-30% efficiency improvement vs R-22-era equipment, supporting payback within 7-12 years on typical residential installations. For interim continuation on existing R-22 equipment: reclaimed R-22 remains legal, or HFC drop-in retrofits (R-407C, R-422D, R-438A) preserve the existing equipment chassis.
Regulatory and transition context
Both refrigerants sit in an active regulatory transition driven by climate-impact rules. The transitions affect availability, pricing, and new-equipment specification.
- EPA AIM Act (40 CFR Part 84): US HFC production / import phase-down. Cap declines from 90% allocation (2022) to 15% by 2036. One or both refrigerants here are AIM Act-affected. New residential AC equipment over 700 GWP prohibited as of 2025.
- EU F-Gas Regulation (517/2014, updated 2024/573): European stationary refrigeration GWP cap typically 150 (much tighter than AIM Act). Drives earlier adoption of very-low-GWP options in European markets.
- Kigali Amendment to Montreal Protocol (2016): international HFC phase-down framework (198 countries). The AIM Act and EU F-Gas are regional implementations. Schedules differ by country group.
- ASHRAE 34-2022: safety classification (A1, A2L, A3, B1, B2L). For A2L refrigerants like R-32, R-454B, R-454C, R-455A: equipment must be A2L-certified, charge limits per IEC 60335-2-40 apply.
Standard transition procedure — R-22 → R-32
Step-by-step service procedure for transitioning an existing R-22 system to R-32, derived from the property differences above. Always cross-check equipment OEM service literature for the specific equipment being serviced. The steps below codify EPA Section 608 requirements (recovery, evacuation, documentation) plus refrigerant-specific accommodations for lubricant, safety class, pressure envelope, and glide differences. Skipping any of the regulatory steps (leak check, recovery, evacuation, documentation) creates compliance liability; skipping refrigerant-specific accommodations creates equipment-failure risk.
- EPA Section 608 leak-check first.Verify the existing system isn't leaking before any work. If it's leaking, find and repair the leak — adding refrigerant (existing or new) to a leaking system violates 40 CFR Part 82.
- Recover R-22. Use a recovery machine rated for A1refrigerants. Recover into properly-labeled cylinders; don't mix recovered R-22 with virgin or recovered R-32 (cross-contamination invalidates reclaim).
- Drain MO lubricant and flush. R-22 runs on MO/AB; R-32 requires POE. Drain the compressor crankcase, accumulator, and any oil traps. Flush the system with a compatible flush solvent or run POE lubricant through the system and re-drain to clear residual MO. Mixing mineral oil with POE in an HFC system produces oil-return failures within hours of operation.
- Replace filter-drier. Install a new drier rated for R-32 (POElubricant). Filter-driers are single-use after exposure to a refrigerant; the old drier may have absorbed contaminants you don't want carrying into the new charge.
- Pressure-test and evacuate to ≤500 microns. Pressure-test with dry nitrogen to verify no leaks. Pull deep vacuum and hold ≥30 minutes with vacuum pump isolated to confirm no leak-back. This step is non-negotiable — non-condensables (air, moisture) trapped in the system raise discharge pressure and damage the compressor.
- Charge R-32 by weight to nameplate — adjusted for the +67% pressure difference vs R-22. Use a calibrated recovery / charging scale. Charging by gauge feel produces frequent overcharge errors.
- Verify with SH and SC at steady state. R-32 has minimal glide (pure or near-azeotrope), so the bubble = dew curve and standard PT chart math applies. Target SC = 8-12°F for TXV systems; target SH per OEM nameplate.
- A2L safety compliance. R-32 is A2L(mildly flammable). Field retrofit of A1-only equipment to A2L generally isn't possible — equipment must be A2L-certified per UL / IEC 60335-2-40 (sealed motors, charge limits per room volume, leak detection on larger systems). The realistic path is full equipment replacement, not refrigerant swap.
- Document and label. Update the equipment data plate to reflect R-32. EPA Section 608 requires records of refrigerant added / recovered; OEM warranty may require documentation of approved-refrigerant substitution.
Lifecycle and operational context
Beyond the per-service-call decision, the R-22 ↔ R-32 choice sits inside a broader regulatory and lifecycle context. The transition direction (which is the predecessor, which is the successor) is driven by climate policy and the AIM Act phase-down, not technical preference alone.
- GWP profile: R-22 = 1,810 GWP (AR5); R-32 = 675 GWP. Switching from R-22 to R-32 reduces direct refrigerant climate impact by 63%.
- AIM Act exposure: R-32 is AIM Act-affected; R-22 is not — the transition increases regulatory exposure (unusual direction). One or both refrigerants exceed the 700 GWP cap for new residential AC equipment (in effect since January 1, 2025).
- EU F-Gas Regulation: Both refrigerants exceed the EU F-Gas 150 GWP cap for new stationary refrigeration. Selection in European market favors very-low-GWP HFOs and natural refrigerants.
- Service supply outlook: Service supply of AIM Act-affected refrigerants persists during phase-down via reclaimed and allocated production, with prices rising as supply tightens. Plan for refrigerant cost escalation over equipment lifetime.
- TEWI / LCCP framing: Total Equivalent Warming Impact accounts for both direct refrigerant emissions (leakage, end-of-life) and indirect emissions from equipment energy consumption. For HVAC equipment with ≤5% annual leak rate, indirect emissions typically dominate TEWI by 80-90% — meaning equipment efficiency matters more than refrigerant GWP for total climate impact. For commercial refrigeration with higher leak rates, the balance can tip toward favoring low-GWP refrigerants.
Regulatory sources: EPA AIM Act (40 CFR Part 84), EU F-Gas Regulation 517/2014 and update 2024/573, Kigali Amendment to the Montreal Protocol (2016), Japan Fluorocarbon Emissions Control Law. GWP values per IPCC AR5 (2013) WG-I Table 8.A.1.
Service implications — R-22 → R-32
What a service technician needs to know when transitioning from R-22to R-32 (or comparing them for new equipment specification). Two real-world scenarios show how the difference plays out in practice.
Pressure envelope check for R-22 → R-32
Scenario · Field tech needs to know: do R-22 service tools handle R-32, or does the pressure delta require new equipment? PT chart comparison at service temperatures gives the answer.
| Temp | R-22 | R-32 | Δ |
|---|---|---|---|
| 40°F | 69 PSIG | 121 PSIG | +76.4% |
| 70°F | 121 PSIG | 206 PSIG | +69.5% |
| 95°F | 182 PSIG | 303 PSIG | +66.6% |
Service-side implications: lubricant and safety
Scenario · Beyond pressure envelope, the switch from R-22 to R-32 affects lubricant, safety class, and operating procedure.
| Concern | R-22 | R-32 | Action |
|---|---|---|---|
| Lubricant | MO/AB | POE | Oil change required |
| Safety class | A1 | A2L | A2L equipment |
| Glide | 0.0°F | 0.0°F | Minor |
When to use which tool for this comparison
- R-22 full reference — properties, PT chart, lubricant, retrofit options for R-22.
- R-32 full reference — properties, PT chart, lubricant, retrofit options for R-32.
- PT Comparison Tool — overlay any 2-4 refrigerants' PT curves interactively.
- Retrofit Compatibility Calculator — five-criterion compatibility analysis with verdict.
- Refrigerant Comparison Guide — long-form sourced reference for all common HVAC refrigerant comparisons.
Frequently asked
›Is R-32 a direct replacement for R-22?
No. R-32 is not a retrofit refrigerant for R-22 equipment — it's the modern refrigerant for new R-32-designed equipment. The differences (safety class, pressure, lubricant, capacity) require fundamentally different equipment design. The two refrigerants serve the same application (residential AC) but in completely separate equipment generations.
›Why does R-32 have higher pressures than R-22?
Smaller molecule with higher vapor pressure. R-32 (CH₂F₂, difluoromethane) is a smaller molecule than R-22 (CHClF₂, chlorodifluoromethane); at the same temperature R-32 has higher saturation pressure. R-32 at 70°F is 206 PSIG vs R-22 at 121 PSIG — about 70% higher. The pressure difference is intrinsic to the chemistry and requires equipment redesign for safe operation.
›What's R-32's GWP compared to R-22?
R-32 GWP 675 per IPCC AR5 (the EPA AIM Act figure) vs R-22 GWP 1810. R-32 is about 63% lower GWP than R-22. R-32 sits just below the AIM Act 700-GWP threshold for new residential AC equipment. R-22 is phased out for ozone-depletion (ODP 0.055) under the Montreal Protocol — its GWP wasn't the binding regulatory concern, but R-32's better GWP is part of the modern transition story.
›Is R-32 flammable? Should I worry?
R-32 is ASHRAE class A2L — mildly flammable with low burning velocity (≤10 cm/s) and limited heat of combustion. A2L equipment includes sealed motors, leak detection sensors, charge limits, and ignition-source isolation that mitigate the flammability risk to acceptable levels. R-32 has been deployed in millions of installations globally (predominantly Japan, Europe, Australia) with strong safety record. For homeowners: properly-installed R-32 equipment is safe; the A2L classification matters for technician procedures, not for everyday operation.
›Should I retrofit my R-22 system or replace it with R-32 equipment?
Retrofit to R-32 is not possible (equipment must be A2L-rated, which old R-22 equipment isn't). The realistic options for R-22 equipment: (1) continue on reclaimed R-22, (2) retrofit to a mineral-oil-compatible HFC blend like R-422D or R-438A for a 5-10 year bridge, (3) full replacement with new R-32 or R-454B equipment. The choice depends on equipment age, condition, and capital availability. Equipment over 15 years old with significant repair needs typically justifies replacement.
›What lubricant does each refrigerant use?
R-22 uses mineral oil (MO) or alkylbenzene (AB) — the legacy CFC/HCFC era lubricants. R-32 requires polyolester (POE) oil — the HFC/HFO era lubricant. POE is hygroscopic (absorbs water aggressively) and requires more careful moisture management during service. The lubricant change is one of the structural blockers preventing R-22 to R-32 retrofit.
›Why didn't R-32 replace R-22 directly in 2010?
Timeline. R-32 was not widely available as a residential AC refrigerant until ~2015 (Daikin launched commercially in Japan in 2012-2013, with US arrival 2018-2020). When R-22 was phased out of new equipment in 2010, R-410A (HFC blend, A1 non-flammable) was the dominant replacement — R-410A's A1 safety class matched the existing R-22 equipment design paradigm. R-32 only became the new-equipment standard in 2024-2025 when AIM Act pressure on R-410A's GWP (2088) made the A2L transition unavoidable.
R-22 full reference
PT chart, properties, retrofit guidance.
R-32 full reference
PT chart, properties, retrofit guidance.