R-22 (Legacy HCFC)
R-22 Superheat & Subcooling Calculator
Check charge on legacy R-22 systems with the calculator preloaded for R-22. Full PT chart, and TXV and fixed orifice targets.
R-22 Pressure-Temperature Chart
| R-22 | ||
|---|---|---|
| Pressure (psig) | Sat. Temp (°F) | Publisher spread (°F) |
| 1 | -40°F | 1.00 |
| 3 | -35°F | 0.87 |
| 5 | -30°F | 0.20 |
| 7 | -25°F | 0.80 |
| 10 | -20°F | 0.36 |
| 13 | -15°F | 0.33 |
| 17 | -10°F | 0.69 |
| 20 | -5°F | 0.14 |
| 24 | 0°F | 0 |
| 28 | 5°F | 0.35 |
| 33 | 10°F | 0.20 |
| 38 | 15°F | 0.19 |
| 43 | 20°F | 0.09 |
| 49 | 25°F | 0.16 |
| 55 | 30°F | 0 |
| 62 | 35°F | 0.35 |
| 69 | 40°F | 0.27 |
| 76 | 45°F | 0.07 |
| 84 | 50°F | 0.06 |
| 93 | 55°F | 0.22 |
| 102 | 60°F | 0.21 |
| 111 | 65°F | 0.15 |
| 121 | 70°F | 0.20 |
| 132 | 75°F | 0.09 |
| 144 | 80°F | 0.17 |
| 156 | 85°F | 0.12 |
| 168 | 90°F | 0.16 |
| 182 | 95°F | 0.07 |
| 196 | 100°F | 0.03 |
| 211 | 105°F | 0.06 |
| 226 | 110°F | 0.13 |
| 243 | 115°F | 0.06 |
| 260 | 120°F | 0 |
About the spread column. It is the widest gap in saturation temperature between the published tables we hold, at that pressure, on the saturation column. Across this chart the widest is 1.00°F, at 1 psig. Our table and 1 other published table are compared here: 1 is a separate publisher. A narrow spread means the charts agree, which is not the same as the charts being right: they are all computed from equations of state fitted to lab data, and no field measurement settles it.
- Checked against NIST REFPROP 9.0, as printed by iGas and Arkema, agrees to the whole psig at all 33 shipped points, raw spread at most 0.4 psig [separate publisher]
A separate publisher can catch a transcription, edition or rounding error. A cross-check marked same model resolves to the same equation of state as the base table, so it is a consistency check rather than independent confirmation. One marked same printing prints numbers identical to another table listed here, so the two are one witness and we do not count them twice. Sources last re-verified 2026-08-25.
The anchors: 69 psig is a 40°F evaporator and 196 psig is a 100°F condenser. If you spend most of your week on R-410A, recalibrate your instincts before touching an R-22 system; 120 psig suction is normal on R-410A and wildly overcharged territory on R-22.
R-22 Target Superheat & Subcooling
| Metering device | Target superheat | Target subcooling | Charging method |
|---|---|---|---|
| TXV | 10–18°F | 8–14°F | Charge by subcooling; the TXV holds superheat |
| Fixed orifice (piston) | 5–25°F | 4–12°F | Charge by superheat from the manufacturer charging chart |
Note the targets sit a couple degrees higher than R-410A norms. R-22-era equipment also used fixed orifices far more often than modern gear, so expect to charge by the superheat chart more frequently on these calls.
Servicing R-22 in 2026
R-22 was the residential standard for half a century. From 2010 EPA allowed new R-22 to be produced or imported only for equipment manufactured before that date, and U.S. production and import ended on January 1, 2020. Since then, in EPA's words, “only recycled, reclaimed, or previously produced HCFC-22 can be used to service existing equipment.” R-22 systems run on mineral oil, and every one of them is now a servicing-only proposition: the charge is worked with what EPA allows.
Servicing-only changes how you use superheat and subcooling on these calls. On a modern system, a slightly low charge is a trim; on R-22 it is a decision point. Confirm the diagnosis with both readings before committing refrigerant, quote the leak search with the top-off, and put the repair-versus-replace numbers in front of the customer while the gauges are still on the ports.
R-22 Charging Notes
R-22 is a pure single-component HCFC with zero glide, so PT work is simple and vapor charging does not fractionate anything. It runs on mineral oil, which matters mostly when retrofit blends enter the conversation: R-407C needs a full oil conversion to POE, while blends like R-438A tolerate residual mineral oil. Never mix a retrofit blend into remaining R-22; recover the full charge, follow the retrofit procedure, and relabel the equipment.
On charging technique, nothing exotic: charge to subcooling on the minority of R-22 systems with a TXV, and to the manufacturer superheat chart on fixed-orifice systems using outdoor ambient and indoor wet bulb. Verify airflow first. Two decades of dust in a blower wheel and a half-plugged evaporator produce the same low suction pressure a leak does, and the difference is a free fix versus a very expensive pound of refrigerant.
Worked Example: Aging R-22 Condenser, Suspected Leak
A 2008 R-22 split system with a TXV, cooling poorly on an 88°F day. Field readings: suction pressure 58 psig, suction line temperature 55°F, liquid pressure 168 psig, liquid line temperature 84°F.
Saturated suction temp at 58 psig ≈ 32°F
Superheat = 55°F − 32°F = 23°F
Saturated liquid temp at 168 psig = 90°F
Subcooling = 90°F − 84°F = 6°F
Diagnosis: Superheat 23°F is well above the 10-18°F TXV target and subcooling 6°F is below the 8-14°F target. High superheat with low subcooling is the low-charge signature: the evaporator is starved and the condenser has no liquid seal. On an 18-year-old system, electronic leak-search the evaporator coil and service valves before adding anything, then have the repair-or-replace conversation with the refrigerant quote in hand.
R-22 Service FAQs
What is normal superheat for R-22?
With a TXV, target superheat for R-22 is 10-18°F. With a fixed orifice, which is common on R-22-era equipment, target superheat swings widely with conditions (roughly 5-25°F) and must come from the manufacturer charging chart using outdoor ambient and indoor wet bulb. Charging an old piston system to a single guessed superheat number is one of the classic R-22 field errors.
What is normal subcooling for R-22?
Target subcooling for R-22 with a TXV is 8-14°F, measured at the liquid line off the condenser. On the many fixed-orifice R-22 systems still running, subcooling typically lands around 4-12°F, but superheat is the charging indicator on those systems and subcooling is a cross-check.
Can I still buy R-22?
EPA ended U.S. production and import of R-22 on January 1, 2020, and says an existing R-22 system can still be serviced: "After 2020, only recycled, reclaimed, or previously produced HCFC-22 can be used to service existing equipment."
Is it illegal to run an R-22 system?
No. Owning, running, and servicing an existing R-22 system is completely legal. The phase-out stopped new production and import of the refrigerant, not the use of existing equipment. What is illegal is knowingly venting it: R-22 must be recovered with certified equipment.
Can I replace R-22 with R-410A in the same system?
No. R-410A runs roughly 60 percent higher pressures than R-22; an R-22 compressor, coils, and line components are not rated for it, and R-410A requires POE oil where R-22 systems hold mineral oil. Moving to R-410A or an A2L refrigerant means replacing the equipment, not the refrigerant.
What refrigerants can replace R-22 in an existing system?
Retrofit blends exist: R-407C (requires flushing mineral oil and converting to POE) and drop-in style options like R-438A (MO99) or R-422D that tolerate some mineral oil. All lose a little capacity, most add glide, and the TXV or orifice may need adjustment. Price the retrofit honestly against replacement before committing.
Should I repair or replace an R-22 system?
This page does not make that call; the leak, the failed part and what the refrigerant costs on the day decide it. EPA says an existing R-22 system can keep running and be serviced: "After 2020, only recycled, reclaimed, or previously produced HCFC-22 can be used to service existing equipment." Confirm the diagnosis with superheat and subcooling before committing refrigerant.
Other Refrigerants & Related Tools
R-454B Superheat & Subcooling Calculator
The A2L replacement for R-410A in new ducted systems. PT chart, TXV targets, and A2L charging notes.
R-32 Superheat & Subcooling Calculator
Pure A2L refrigerant used in ductless mini splits. Zero glide, higher pressures, hotter discharge.
R-410A Superheat & Subcooling Calculator
The dominant installed base from 2010 to 2025. PT chart and TXV charging targets.
R-134a Superheat & Subcooling Calculator
Medium-temp refrigeration, chillers, and automotive AC. PT chart and charging targets.
All-Refrigerant Calculator
The full calculator with 10+ refrigerants including R-407C with glide handling, plus the four-quadrant diagnostic guide.
Target Superheat Calculator
Charging a fixed-orifice (piston) system? Set the charge by target superheat from indoor wet-bulb and outdoor dry-bulb, compared to your measured superheat.
Normal Superheat & Subcooling Values
The target numbers by refrigerant and metering device, with what a high or low reading means. R-410A, R-454B, R-32, R-22, R-134a, and R-407C in one reference.
How to Calculate Superheat & Subcooling
The formulas, the step-by-step field method, and worked examples for R-410A and R-22. The math behind the calculator.
Printable Superheat & Subcooling Chart
Target ranges by refrigerant plus PT charts for R-410A, R-454B, and R-22, formatted to print or save as a PDF for the truck.
Subcooling on a Heat Pump
Where to measure on a heat pump in each mode, each maker's own heating-mode charging rule, and when the cooling-mode subcooling number still applies.
A2L Charge Limit Calculator
Maximum A2L charge for a room, or minimum room area for a charge, per UL 60335-2-40 and ASHRAE 15.2. Covers R-454B, R-32, and 6 more refrigerants.
EPA Refrigerant Leak Rate Calculator
Topping off a covered 15+ lb appliance triggers a leak rate calculation under 40 CFR 84.106 as of January 1, 2026. Residential and light commercial air conditioning and heat pumps are excluded by 84.106(a)(3)(ii), so on most split systems the rate is informational. Run the EPA math and check the thresholds.
BTU / HVAC Load Calculator
Size the system by climate zone, insulation, windows, and duct location with automatic tonnage recommendations.
Quoting the replacement? Size it right this time.
R-22-era systems were routinely oversized, and copying the old tonnage copies the mistake. Run the load by climate zone, insulation, and windows before writing the quote.