Field reference, by refrigerant
Normal Superheat & Subcooling Values by Refrigerant
The target superheat and subcooling numbers techs actually charge to, by refrigerant and metering device, with what a high or low reading means. These are field rule-of-thumb envelopes, so the equipment nameplate or charging chart is always the final word.
Target Values by Refrigerant (TXV & Fixed Orifice)
The ranges below are field rule-of-thumb envelopes measured at steady state. They tell you whether a reading deserves a second look. The refrigerant mostly changes which pressure-temperature chart you read, not the target itself.
| Refrigerant | Class | TXV superheat | TXV subcooling | Fixed superheat | Fixed subcooling |
|---|---|---|---|---|---|
| R-410A | HFC | 8–15°F | 8–14°F | 5–20°F | 4–10°F |
| R-454B | A2L | 8–15°F | 8–14°F | 5–20°F | 4–10°F |
| R-32 | A2L | 8–15°F | 8–14°F | 5–20°F | 4–10°F |
| R-22 | HCFC | 10–18°F | 10–16°F | 5–25°F | 4–12°F |
| R-134a | HFC | 8–14°F | 8–14°F | 5–18°F | 4–10°F |
| R-407C | HFC | 8–15°F | 8–14°F | 5–20°F | 4–10°F |
On a TXV, charge by subcooling (the valve holds superheat). On a fixed orifice, charge by superheat from the manufacturer charging chart for the indoor wet-bulb and outdoor dry-bulb.
What a High or Low Reading Means
For a measured superheat or subcooling, the band tells you whether it is too low, on target, or too high, and what usually causes each. The direction means the same thing on every refrigerant, because it comes from the refrigeration cycle, not the fluid. One hard limit applies everywhere: a superheat at or near zero means liquid is leaving the coil and can slug the compressor, so recover charge and do not add.
Normal Superheat & Subcooling for R-410A
On a R-410A system with a TXV, normal superheat is 8–15°F and normal subcooling is 8–14°F. On a fixed-orifice (piston) system, superheat runs 5–20°F (set by the manufacturer charging chart from indoor wet-bulb and outdoor dry-bulb) and subcooling 4–10°F. These are field rule-of-thumb envelopes: always confirm against the equipment nameplate or charging chart.
| Reading (°F, TXV) | Verdict | What it means |
|---|---|---|
| Below 8°F | Too low | Too much liquid is reaching the evaporator, usually an overcharge or a flooded/overfed evaporator (low indoor load or restricted airflow). Superheat at or near zero means liquid is leaving the coil and can slug the compressor: recover charge, do not add. |
| 8–15°F | On target | On target for this reading. On a TXV system confirm the charge with subcooling and the manufacturer's rated value before signing off. |
| Above 15°F | Too high | The evaporator is starved. Usually a low charge, but first rule out a restriction (plugged filter-drier, stuck TXV) or low indoor airflow, which raise superheat the same way and are not fixed by adding refrigerant. |
| Reading (°F, TXV) | Verdict | What it means |
|---|---|---|
| Below 8°F | Too low | The condenser is not stacking a full liquid column, usually a low charge or a leak. Find and fix the leak before adding refrigerant. |
| 8–14°F | On target | On target. Subcooling is the primary charge indicator on a TXV system because the valve holds superheat. |
| Above 14°F | Too high | The condenser is holding too much liquid, usually an overcharge. Rule out low or dirty condenser airflow first, then recover in small steps and recheck. |
Calculate R-410A superheat & subcooling from your gauge readings
Normal Superheat & Subcooling for R-454B
On a R-454B system with a TXV, normal superheat is 8–15°F and normal subcooling is 8–14°F. On a fixed-orifice (piston) system, superheat runs 5–20°F (set by the manufacturer charging chart from indoor wet-bulb and outdoor dry-bulb) and subcooling 4–10°F. These are field rule-of-thumb envelopes: always confirm against the equipment nameplate or charging chart.
R-454B is a zeotropic blend: read superheat from the dew point and subcooling from the bubble point.
| Reading (°F, TXV) | Verdict | What it means |
|---|---|---|
| Below 8°F | Too low | Too much liquid is reaching the evaporator, usually an overcharge or a flooded/overfed evaporator (low indoor load or restricted airflow). Superheat at or near zero means liquid is leaving the coil and can slug the compressor: recover charge, do not add. |
| 8–15°F | On target | On target for this reading. On a TXV system confirm the charge with subcooling and the manufacturer's rated value before signing off. |
| Above 15°F | Too high | The evaporator is starved. Usually a low charge, but first rule out a restriction (plugged filter-drier, stuck TXV) or low indoor airflow, which raise superheat the same way and are not fixed by adding refrigerant. |
| Reading (°F, TXV) | Verdict | What it means |
|---|---|---|
| Below 8°F | Too low | The condenser is not stacking a full liquid column, usually a low charge or a leak. Find and fix the leak before adding refrigerant. |
| 8–14°F | On target | On target. Subcooling is the primary charge indicator on a TXV system because the valve holds superheat. |
| Above 14°F | Too high | The condenser is holding too much liquid, usually an overcharge. Rule out low or dirty condenser airflow first, then recover in small steps and recheck. |
Calculate R-454B superheat & subcooling from your gauge readings
Normal Superheat & Subcooling for R-32
On a R-32 system with a TXV, normal superheat is 8–15°F and normal subcooling is 8–14°F. On a fixed-orifice (piston) system, superheat runs 5–20°F (set by the manufacturer charging chart from indoor wet-bulb and outdoor dry-bulb) and subcooling 4–10°F. These are field rule-of-thumb envelopes: always confirm against the equipment nameplate or charging chart.
| Reading (°F, TXV) | Verdict | What it means |
|---|---|---|
| Below 8°F | Too low | Too much liquid is reaching the evaporator, usually an overcharge or a flooded/overfed evaporator (low indoor load or restricted airflow). Superheat at or near zero means liquid is leaving the coil and can slug the compressor: recover charge, do not add. |
| 8–15°F | On target | On target for this reading. On a TXV system confirm the charge with subcooling and the manufacturer's rated value before signing off. |
| Above 15°F | Too high | The evaporator is starved. Usually a low charge, but first rule out a restriction (plugged filter-drier, stuck TXV) or low indoor airflow, which raise superheat the same way and are not fixed by adding refrigerant. |
| Reading (°F, TXV) | Verdict | What it means |
|---|---|---|
| Below 8°F | Too low | The condenser is not stacking a full liquid column, usually a low charge or a leak. Find and fix the leak before adding refrigerant. |
| 8–14°F | On target | On target. Subcooling is the primary charge indicator on a TXV system because the valve holds superheat. |
| Above 14°F | Too high | The condenser is holding too much liquid, usually an overcharge. Rule out low or dirty condenser airflow first, then recover in small steps and recheck. |
Calculate R-32 superheat & subcooling from your gauge readings
Normal Superheat & Subcooling for R-22
On a R-22 system with a TXV, normal superheat is 10–18°F and normal subcooling is 10–16°F. On a fixed-orifice (piston) system, superheat runs 5–25°F (set by the manufacturer charging chart from indoor wet-bulb and outdoor dry-bulb) and subcooling 4–12°F. These are field rule-of-thumb envelopes: always confirm against the equipment nameplate or charging chart.
| Reading (°F, TXV) | Verdict | What it means |
|---|---|---|
| Below 10°F | Too low | Too much liquid is reaching the evaporator, usually an overcharge or a flooded/overfed evaporator (low indoor load or restricted airflow). Superheat at or near zero means liquid is leaving the coil and can slug the compressor: recover charge, do not add. |
| 10–18°F | On target | On target for this reading. On a TXV system confirm the charge with subcooling and the manufacturer's rated value before signing off. |
| Above 18°F | Too high | The evaporator is starved. Usually a low charge, but first rule out a restriction (plugged filter-drier, stuck TXV) or low indoor airflow, which raise superheat the same way and are not fixed by adding refrigerant. |
| Reading (°F, TXV) | Verdict | What it means |
|---|---|---|
| Below 10°F | Too low | The condenser is not stacking a full liquid column, usually a low charge or a leak. Find and fix the leak before adding refrigerant. |
| 10–16°F | On target | On target. Subcooling is the primary charge indicator on a TXV system because the valve holds superheat. |
| Above 16°F | Too high | The condenser is holding too much liquid, usually an overcharge. Rule out low or dirty condenser airflow first, then recover in small steps and recheck. |
Calculate R-22 superheat & subcooling from your gauge readings
Normal Superheat & Subcooling for R-134a
On a R-134a system with a TXV, normal superheat is 8–14°F and normal subcooling is 8–14°F. On a fixed-orifice (piston) system, superheat runs 5–18°F (set by the manufacturer charging chart from indoor wet-bulb and outdoor dry-bulb) and subcooling 4–10°F. These are field rule-of-thumb envelopes: always confirm against the equipment nameplate or charging chart.
| Reading (°F, TXV) | Verdict | What it means |
|---|---|---|
| Below 8°F | Too low | Too much liquid is reaching the evaporator, usually an overcharge or a flooded/overfed evaporator (low indoor load or restricted airflow). Superheat at or near zero means liquid is leaving the coil and can slug the compressor: recover charge, do not add. |
| 8–14°F | On target | On target for this reading. On a TXV system confirm the charge with subcooling and the manufacturer's rated value before signing off. |
| Above 14°F | Too high | The evaporator is starved. Usually a low charge, but first rule out a restriction (plugged filter-drier, stuck TXV) or low indoor airflow, which raise superheat the same way and are not fixed by adding refrigerant. |
| Reading (°F, TXV) | Verdict | What it means |
|---|---|---|
| Below 8°F | Too low | The condenser is not stacking a full liquid column, usually a low charge or a leak. Find and fix the leak before adding refrigerant. |
| 8–14°F | On target | On target. Subcooling is the primary charge indicator on a TXV system because the valve holds superheat. |
| Above 14°F | Too high | The condenser is holding too much liquid, usually an overcharge. Rule out low or dirty condenser airflow first, then recover in small steps and recheck. |
Calculate R-134a superheat & subcooling from your gauge readings
Normal Superheat & Subcooling for R-407C
On a R-407C system with a TXV, normal superheat is 8–15°F and normal subcooling is 8–14°F. On a fixed-orifice (piston) system, superheat runs 5–20°F (set by the manufacturer charging chart from indoor wet-bulb and outdoor dry-bulb) and subcooling 4–10°F. These are field rule-of-thumb envelopes: always confirm against the equipment nameplate or charging chart.
R-407C is a zeotropic blend: read superheat from the dew point and subcooling from the bubble point.
| Reading (°F, TXV) | Verdict | What it means |
|---|---|---|
| Below 8°F | Too low | Too much liquid is reaching the evaporator, usually an overcharge or a flooded/overfed evaporator (low indoor load or restricted airflow). Superheat at or near zero means liquid is leaving the coil and can slug the compressor: recover charge, do not add. |
| 8–15°F | On target | On target for this reading. On a TXV system confirm the charge with subcooling and the manufacturer's rated value before signing off. |
| Above 15°F | Too high | The evaporator is starved. Usually a low charge, but first rule out a restriction (plugged filter-drier, stuck TXV) or low indoor airflow, which raise superheat the same way and are not fixed by adding refrigerant. |
| Reading (°F, TXV) | Verdict | What it means |
|---|---|---|
| Below 8°F | Too low | The condenser is not stacking a full liquid column, usually a low charge or a leak. Find and fix the leak before adding refrigerant. |
| 8–14°F | On target | On target. Subcooling is the primary charge indicator on a TXV system because the valve holds superheat. |
| Above 14°F | Too high | The condenser is holding too much liquid, usually an overcharge. Rule out low or dirty condenser airflow first, then recover in small steps and recheck. |
Calculate R-407C superheat & subcooling from your gauge readings
Superheat and Subcooling, Defined
Superheat
The temperature rise of refrigerant vapor above its saturation (boiling) temperature at the measured suction pressure. Superheat = suction line temperature minus saturated suction temperature. It confirms all liquid has boiled off before the compressor.
Subcooling
The temperature drop of liquid refrigerant below its saturation (condensing) temperature at the measured liquid pressure. Subcooling = saturated liquid temperature minus liquid line temperature. On a TXV system it is the primary indicator of refrigerant charge.
superheat_subcooling tool live, handing back the verdict with its cited source instead of a guess. Then keep the reading as one job in the Intry app.Superheat & Subcooling Values FAQs
Are superheat and subcooling targets the same for every refrigerant?
Mostly yes on a TXV system. Target superheat and subcooling come from the metering device and the operating conditions, not the refrigerant chemistry, so R-410A, R-454B, R-32, and R-407C all target 8–15°F superheat and 8–14°F subcooling. R-22 runs higher (10–18°F and 10–16°F) and R-134a is slightly tighter. What really changes per refrigerant is the pressure-temperature chart you read to get the numbers, plus glide on the blends and the safety class.
Do R-410A and R-454B have the same target superheat?
Yes. Both target 8–15°F superheat and 8–14°F subcooling on a TXV. The targets are set by the metering device and operating conditions, not the fluid. What changes with R-454B is the pressure-temperature chart you read, the small temperature glide (read superheat off the dew point and subcooling off the bubble point), and the A2L safety class.
Do the A2L refrigerants (R-454B and R-32) use different targets than R-410A?
No. On a TXV the A2L refrigerants target the same 8–15°F superheat and 8–14°F subcooling as R-410A. A2L changes the handling, leak detection, and pressure-temperature chart, not the charging targets. For the per-refrigerant pressures and PT chart, see the dedicated R-454B and R-32 pages linked below.
Why is R-22 superheat and subcooling higher than R-410A?
R-22 systems are charged to higher targets: 10–18°F superheat and 10–16°F subcooling on a TXV, against 8–15°F and 8–14°F for R-410A. Treat it as a rule-of-thumb envelope for legacy equipment and let the unit nameplate or charging chart override it. The way you read the numbers is the same: superheat is suction line temperature minus saturated suction temperature from the R-22 PT chart.
Which refrigerant has the highest superheat and subcooling targets?
Of the common refrigerants, R-22 runs the highest at 10–18°F superheat and 10–16°F subcooling on a TXV. R-410A, R-454B, R-32, and R-407C sit lower at 8–15°F and 8–14°F, and R-134a is tightest on superheat. The targets are a rule-of-thumb envelope for the metering device, not a hard spec, so always confirm against the nameplate.
If the targets are the same across refrigerants, what actually changes?
Three things change even when the target superheat and subcooling stay the same. First, the pressure-temperature chart you read to convert a gauge pressure to a saturation temperature is different for every refrigerant. Second, the zeotropic blends (R-454B, R-407C) have temperature glide, so you read superheat from the dew point and subcooling from the bubble point. Third, the safety class differs: R-454B and R-32 are A2L (mildly flammable) and need A2L leak detection and handling.
R-410A Target Detail
| Metering device | Target superheat | Target subcooling | Charging method |
|---|---|---|---|
| TXV | 8–15°F | 8–14°F | Charge by subcooling; the TXV holds superheat |
| Fixed orifice (piston) | 5–20°F | 4–10°F | Charge by superheat from the manufacturer charging chart |
The superheat and subcooling targets on this page are field rule-of-thumb envelopes, not a single manufacturer specification, so always confirm against the equipment nameplate or the manufacturer charging chart on the unit in front of you. Every number here is derived from the same locked data the Intry calculator uses, so the page and the tool never disagree. The per-refrigerant pressure-temperature charts behind a measured reading are cross-checked against manufacturer and reference data on each dedicated refrigerant page. Updated July 17, 2026.
Calculate It on Your System
These are the targets. To get your actual superheat and subcooling from gauge pressures and line temperatures, use the calculator, and see the four-quadrant diagnosis for your reading.
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-22 Superheat & Subcooling Calculator
Legacy HCFC on reclaimed supply only. PT chart and targets for servicing older systems.
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.
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
Why heat pumps have no subcooling target in heating mode, how to charge by weigh-in, 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 15+ lb system triggers a leak rate calculation under 40 CFR 84.106 as of January 1, 2026. 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.
Have a reading? Get the verdict, not just the number.
Enter your pressures and line temperatures and the calculator returns superheat, subcooling, and a four-quadrant diagnosis against these targets. Free, no login.