HVAC PT Data

Pressure-temperature charts, field calculators and refrigerant data for HVAC/R technicians

PT data: CoolProp 8.0 equations of state, US units

Refrigerant comparisons and replacements

Side-by-side refrigerant comparisons for the questions that come up during the phase-down: whether one refrigerant can go into another's system, what has to change if it can, and how far apart the pressures are. Every page opens with a one-line verdict, then a pressure table computed from the PT data at common evaporating and condensing temperatures, a property table and a component compatibility matrix covering oil, expansion device, filter-drier, recovery equipment, gauges and cylinders.

Replacement pages compare a phased-out refrigerant with several candidates at once. Mixing refrigerants or topping off one with another is never covered as an option: a system holds one refrigerant, and a change means full recovery and a recharge.

  • R-12 vs R-134a

    Can you put R-134a in an R-12 system? It depends. Only as a full retrofit, never added to the R-12. EPA names R-134a as the main retrofit refrigerant for R-12 vehicle A/C. Chemours says it is not a drop-in: the mineral oil, desiccant and service fittings have to change, and R-134a runs higher on the high side.

  • R-134a Replacement Refrigerants

    What replaces R-134a? It depends. It depends on the equipment. For stationary R-134a refrigeration and chillers, R-513A is the A1 retrofit, keeping the POE and running a few psi higher. New vehicles use R-1234yf, and new centrifugal chillers can use R-1234ze(E). Both of those are A2L and are for equipment designed for them, not retrofits.

  • R-134a vs R-1234yf

    Can you put R-1234yf in an R-134a system? No. EPA lists R-1234yf for new vehicles built to SAE J639: flammable-refrigerant label, high-pressure cutoff, relief device and unique fittings. An R-134a car has none of those. The pressures are close (R-1234yf is 3.4 psi higher at 40°F), but the safety class, fittings and service equipment are different.

  • R-22 Replacement Refrigerants

    What replaces R-22 in an existing system? It depends. No blend is a true drop-in. MO99, NU-22B and R-421A usually run on the existing mineral or AB oil. R-407C needs a full change to POE. Every retrofit starts with recovering all the R-22. If the system is being replaced, the new equipment uses R-410A, R-454B or R-32, not an R-22 substitute.

  • R-22 vs MO99 (R-438A)

    Can you mix MO99 with R-22? No. Chemours says not to top off an R-22 system with MO99. Recover all the R-22 first, then charge MO99 as liquid, starting about 10% below the original R-22 weight. Most systems keep their mineral or AB oil, but MO99 is a zeotrope with 7–10°F of glide, so read its own dew and bubble columns.

  • R-22 vs R-134a

    Can you use R-134a in an R-22 system? No. Not as a practical retrofit. EPA's SNAP list does accept HFC-134a as an R-22 substitute in AC, but R-134a runs at about half the suction pressure of R-22 and needs POE oil, so an R-22 compressor and metering device are the wrong size for it. Arkema and Chemours offer other blends for R-22 retrofits.

  • R-22 vs R-32

    Can you put R-32 in an R-22 system? No. R-32 condenses at roughly 130 psi above R-22 at 100°F, needs POE instead of mineral oil, and is an A2L refrigerant that EPA accepts only in new equipment built and listed for it. An R-22 system is repaired with R-22 or a listed retrofit blend, or replaced with new R-32 equipment.

  • R-22 vs R-407C

    Can R-407C replace R-22? Yes. Yes, as a retrofit in DX air conditioning, but not as a top-off. Recover all the R-22, change the oil to POE (Arkema calls for a complete oil change), charge R-407C as liquid, and read its dew and bubble columns separately because glide is about 11°F at 40°F. Arkema does not recommend it for flooded evaporators.

  • R-22 vs R-410A

    Can you put R-410A in an R-22 system? No. R-410A runs 122.6 psi higher than R-22 at 100°F condensing (about 63%), needs POE oil where R-22 systems run mineral or alkylbenzene oil, and was introduced for new equipment only, not as an R-22 retrofit. Moving to R-410A means a new matched system.

  • R-290 vs R-134a

    Can you replace R-134a with R-290 in an existing system? No. EPA's SNAP program accepts R-290 only in new equipment built for it, and Danfoss says converting an R-134a system to R-290 is not recommended because it was never approved for a flammable refrigerant. R-290 also runs far higher pressures and needs a different compressor, metering and charge.

  • R-290 vs R-32

    Can R-290 replace R-32 in an existing heat pump or air conditioner? No. R-290 runs at about half the pressure of R-32, is class A3 rather than A2L, and in US residential AC EPA lists it only for new self-contained room air conditioners. Both are new-equipment refrigerants under SNAP, so a system is charged only with the refrigerant it was designed and listed for.

  • R-290 vs R-600a

    Can you use R-290 in place of R-600a? No. Both are A3 hydrocarbons, but propane runs about five times the pressure of isobutane at 40°F and needs a compressor with a fraction of the displacement. EPA lists each only for new equipment designed for it, so an R-600a appliance is serviced with R-600a and an R-290 unit with R-290.

  • R-404A Replacement Refrigerants

    What replaces R-404A in an existing system? It depends. For retrofits, R-448A and R-449A are the usual picks. They keep the POE oil, and their GWPs (1,387 and 1,397) sit under the 2026 limit of 1,400 for new remote condensing units and supermarkets. R-452A is the transport option. All of them run with 7.5–10.8°F of glide at 40°F evaporating, where R-404A has under 1°F, so superheat and pressure controls must be reset.

  • R-404A vs R-507A

    Can you mix R-404A and R-507A? No. They are different blends: R-404A is a three-component near-azeotrope, R-507A a two-component azeotrope that runs 3.8 psi higher at 40°F evaporating. A mixture matches neither PT chart. Changing refrigerant means recovering the full charge, evacuating and recharging.

  • R-407A vs R-407C

    Is R-407A the same as R-407C? No. Both blend R-32, R-125 and R-134a, but R-407A has more R-125 and less R-134a, so it runs higher pressures and is aimed at medium- and low-temperature refrigeration while R-407C is the AC and medium-temperature blend. Each has its own PT chart; a system is charged with the one on its label.

  • R-407C vs R-410A

    Can you use R-407C in an R-410A system, or R-410A in an R-407C system? No. The pressure curves are far apart: R-410A runs 93.1 psi higher than R-407C at 100°F condensing and 55.2 psi higher at 40°F evaporating. Each system's compressor, metering device and charge are built for its own refrigerant, and Arkema states there is no retrofit or drop-in replacement for R-410A.

  • R-410A replacement: R-410A vs R-454B vs R-32

    Is there a drop-in replacement for R-410A? No. New US residential and light commercial equipment uses R-454B or R-32, both A2L refrigerants that need equipment listed for them under UL 60335-2-40. Neither can go into an existing R-410A system. Arkema states there is no retrofit or drop-in replacement for R-410A, so existing systems keep running on R-410A until they are replaced.

  • R-410A vs R-32

    Can you put R-32 in an R-410A system? No. R-32 is an A2L (mildly flammable) refrigerant and may only be used in new equipment designed and listed for it under UL 60335-2-40. Arkema, which sells R-32, states there is no retrofit or drop-in replacement for R-410A, and Copeland says A2L refrigerants must not be retrofitted into non-A2L compressors or equipment.

  • R-410A vs R-454B

    Can you put R-454B in an R-410A system? No. R-454B is an A2L (mildly flammable) refrigerant and may only go into equipment designed and listed for it under UL 60335-2-40, with refrigerant detection where the standard requires it. Carrier states it is not a drop-in replacement, and Copeland says A2L refrigerants must not be retrofitted into non-A2L compressors or equipment.

  • R-422B vs R-422D

    Are R-422B and R-422D interchangeable? No. Both are A1 R-22 retrofit blends of R-125, R-134a and isobutane, but R-422D carries more R-125 and runs higher pressures and mass flow. Each has its own PT chart and charge behavior, so a system gets one or the other, never a mix of both.

  • R-448A vs R-449A

    Can you mix R-448A and R-449A? No. They are separate five- and four-component blends with their own PT charts. At 40°F evaporating they read the same, but R-449A runs 3.4 psi lower at 100°F condensing and the glide differs. A mix is neither refrigerant: recover, evacuate and recharge with one.

  • R-454A vs R-454B vs R-454C

    Are R-454A, R-454B and R-454C interchangeable? No. All three are A2L blends of R-32 and R-1234yf, but the R-32 share runs from 68.9% (R-454B) to 35% (R-454A) and 21.5% (R-454C). That changes pressure, glide and GWP so much that each has its own PT chart and its own equipment: R-454B for AC and heat pumps, R-454A and R-454C mainly for new commercial refrigeration.

  • R-454B vs R-32

    Can you put R-32 in an R-454B system, or the reverse? No. Both are A2L, but each system is designed and listed for one refrigerant. R-32 runs 13.5 psi higher than R-454B at 40°F evaporating, and Carrier says equipment components, controls and safety requirements are designed around the specified refrigerant. Charge only what is on the nameplate.

  • R-502 Replacement Refrigerants

    What replaces R-502 in an existing system? It depends. R-404A and R-507A are the HFC replacements and need a change to POE oil; R-402A and R-408A are R-22-based service blends that can run on the existing oil, but they contain HCFC-22 and most are no longer produced. Every retrofit starts by recovering all the R-502.

  • R-600a vs R-134a

    Can you convert an R-134a refrigerator to R-600a? No. EPA lists R-600a for new equipment only, and Danfoss says converting an R-134a system to R-600a is not recommended because it was not approved for a flammable refrigerant. R-600a also needs roughly double the compressor displacement, so the R-134a compressor and cap tube do not fit.