R-458A (TdX 20) PT Chart and Refrigerant Profile

Where you will find R-458A

R-458A is Bluon’s TdX 20, an all-HFC R-22 retrofit for direct-expansion split and packaged HVAC systems. Bluon’s FAQ says ASHRAE assigned the R-458A number in June 2016 (Addendum aj to Standard 34-2013) and EPA approved it under SNAP in 2017.

Bluon limits it to high- and medium-temperature use. It is not recommended for low temperature, flooded evaporators or centrifugal compressors. Expect it in converted R-22 residential splits, heat pumps and light commercial rooftops. The nameplate still says R-22, so read the retrofit label. Guideline N-2017 Table 1 assigns it no legacy color.

Its five components include 13.5% R-227ea and 0.6% R-236fa. It has more glide than R-407C, so read its own chart.

Charging R-458A

The archived Bluon FAQ does not say whether to charge liquid or vapor. With a zeotrope this wide, charge liquid so the mix in the system matches the cylinder.

Glide is the main trap: 12.5°F at a 40°F dew point and 10.4°F at a 100°F bubble point. At 40°F this chart gives 50.1 psig dew and 66.7 psig bubble. R-22 at 40°F is 68.6 psig, so an R-22 gauge scale or the bubble column will make suction superheat look far too high. Read:

• the dew column against suction pressure for superheat
• the bubble column against liquid-line pressure for subcooling

Head pressure is close to R-22: 193.8 psig bubble at 100°F against 195.9 psig. Bluon’s own chart, used to check this one, prints vapor (dew) values up to 65°F and liquid (bubble) values from 70°F up; our chart is within 0.7 psi of it.

Bluon’s FAQ retrofit numbers:

1. Start at 80% of the nameplate charge or of the amount recovered, whichever is less.
2. On TXV systems, expect to close the valve 1–4 turns to reach target superheat.
3. Aim for 8–12°F subcooling and 12–20°F superheat at the compressor.

Those are Bluon’s targets, not the equipment maker’s. Where the manufacturer publishes a charging chart for the unit, it governs. On fixed orifices, the target superheat calculator gives the standard target.

Never top off an R-22 system with TdX 20, and do not mix it with any other refrigerant. Bluon says that if more than 20% of the charge is lost, evacuate and recharge with virgin refrigerant; leaks on the liquid line may be topped off.

Oil and compatibility

Bluon says TdX 20 carries a proprietary lubricant additive that makes it miscible with mineral oil, and that its miscibility with mineral oil and AB is similar to R-22. In properly piped systems, the FAQ says no oil change or 20% POE addition is needed. That is a single-source claim; the compressor manufacturer’s approval list takes priority.

Replace the filter-drier during conversion and evacuate to the OEM target, typically 350–500 microns (evacuation guide). Leak-check Schrader cores and seals after the change. See the refrigerant oil guide.

Safety, handling and recovery

R-458A is A1 (lower toxicity, no flame propagation) per Bluon and EPA. It contains no hydrocarbons.

It is a Section 608 high-pressure refrigerant: its computed liquid saturation pressure at 104°F is 220.3 psia (205.6 psig, bubble), inside the 170–355 psia band of 40 CFR 82.152. Type II or Universal certification covers it, and Type I covers factory-sealed units of 5 lb or less. Recover appliances made after Nov 15 1993 to 0 in Hg under 200 lb of charge and 10 in Hg at 200 lb or more (refrigerant recovery).

Cylinders made since Jan 1 2020 should be light green-gray (RAL 7044) under AHRI Guideline N (cylinder colors).

Status and replacements

EPA SNAP lists R-458A (July 21 2017) as acceptable for:

• retrofitting residential and light commercial AC and heat pumps (retrofit only)
• retrofit and new remote condensing units
• retrofit and new industrial process refrigeration

Its AR4 GWP of 1,650 is above every Technology Transitions limit for new equipment in 40 CFR 84.54, including the 1,400 limit for new remote condensing units from July 27 2026. It is not on the 84.54 named lists. Servicing and retrofitting existing equipment remain legal.

Supply is uncertain. On Oct 21 2026, bluon.com was an HVAC data platform with no TdX 20 content, and we could not confirm current manufacture or sale. Check with your distributor before committing to a conversion. Other routes off R-22 are in R-22 replacement options, R-22 vs R-407C and R-22 vs MO99.

Common questions

Is R-458A a drop-in for R-22?

Bluon sold it as a retrofit with no oil change in properly piped DX systems, and EPA accepts it for retrofitting R-22 AC. The R-22 must still be recovered, and the TXV usually needs adjusting.

R-458A vs R-22: what changes on the gauges?

Head pressure is close to R-22, but the 12.5°F glide means suction must be read against the dew column, which sits well below R-22’s pressure at the same temperature.