R407C PT Chart Calculator: Master This R22 Replacement (Free Tool)
You are servicing an older air conditioner or heat pump. It was retrofitted from R-22 to R-407C. Or you are working on a newer commercial system that uses R-407C. You need to know the pressure-temperature relationship. But R-407C is different from R-22 and R-410A.
R-407C is a zeotropic blend of three HFC refrigerants (R-32, R-125, and R-134a) . It has a temperature glide. This means it has two saturation temperatures at a given pressure: bubble point (liquid) and dew point (vapor). You cannot use a simple single-number PT chart like you do for R-22.
Today, I give you a free R407C PT Chart Calculator. This tool uses the correct bubble and dew point data for this refrigerant. You enter pressure or temperature, and the calculator shows both saturation temperatures or the bubble and dew pressures.
What is R-407C? (Simple Explanation)
R-407C is a non-ozone-depleting HFC refrigerant blend designed to replace R-22 in existing air conditioning systems . It is a zeotropic blend of three refrigerants:
| Component | Percentage (by mass) |
|---|---|
| R-32 (Difluoromethane) | 23% |
| R-125 (Pentafluoroethane) | 25% |
| R-134a (Tetrafluoroethane) | 52% |
Key properties:
| Property | Value |
|---|---|
| ASHRAE Number | R-407C |
| Safety Classification | A1 (Non-Flammable) |
| GWP (100 yr) | 1,774 |
| ODP | 0 |
| Normal Boiling Point | -46.5°F (-43.9°C) |
| Critical Temperature | 186.9°F (86.0°C) |
| Temperature Glide | ~8-12°F |
Why This R407C PT Chart Calculator Matters
Here is why you need a dedicated PT tool for R-407C.
Reason 1: R-407C has a temperature glide
R-407C is a zeotropic blend. It changes composition as it evaporates and condenses, creating a temperature glide between the bubble and dew points . For accurate charging, you need to know both.
Reason 2: You need two PT tables
R-407C has two different PT relationships. Table 31 is for superheat and operating controls (vapor). Table 32 is for subcooling only (liquid) . Use the wrong one, and you will misdiagnose the system.
Reason 3: R-407C is still common
R-407C is widely used in retrofitted R-22 air conditioning systems, chillers, and commercial refrigeration .
LIVE R407C PT Chart Calculator
Enter either pressure or temperature. The calculator shows both bubble and dew values.
R-407C PT Chart Calculator
Look up R-407C bubble and dew point pressures from temperature — or temperature from pressure. Calculate superheat and subcooling. Full PT table with charging guide for HVAC technicians.
R-407C Pressure Temperature Calculator
// Bubble · Dew · Superheat · Subcooling · Charging Guide · 2025
For R-407C superheat, use the dew point (vapor line) as your saturation reference. Enter your low-side suction pressure and suction line temperature.
For R-407C subcooling, use the bubble point (liquid line) as your saturation reference. Enter your high-side liquid line pressure and liquid line temperature.
R-407C has temperature glide — notice bubble and dew pressures differ at each temperature. Click any row to load into the PT Lookup calculator.
| Temp (°F) | Temp (°C) | 🔵 Bubble (PSIG) | 🟣 Dew (PSIG) | 🔵 Bubble (kPa) | 🟣 Dew (kPa) | Glide (°F) | Range |
|---|
What Is R-407C?
R-407C is a zeotropic refrigerant blend. It contains three HFC refrigerants mixed together. Those are R-32 (23%), R-125 (25%), and R-134a (52%). It was designed as a drop-in alternative to R-22 in existing systems, and it works in residential and commercial air conditioning systems.
The most important thing to understand about R-407C is its temperature glide. Unlike R-22 or R-410A, R-407C does not stay at a single temperature as it evaporates or condenses. It shifts temperature by about 9 to 11 degrees Fahrenheit during the phase change. This creates two different saturation points at every pressure — the bubble point and the dew point.
Bubble Point vs Dew Point — What Is the Difference?
This is the most important concept when working with R-407C. You need to know which data point to use for each calculation.
- Bubble Point (Liquid Saturated): The temperature at which the first bubble of vapor forms as a liquid is heated. This applies to the liquid line. Always use bubble point pressure when calculating subcooling.
- Dew Point (Vapor Saturated): The temperature at which the first drop of liquid forms as a vapor cools. This applies to the suction line. Always use dew point pressure when calculating superheat.
- Temperature Glide: The difference between bubble and dew point temperature at a constant pressure. For R-407C this is approximately 9–11°F (5–6°C).
How to Use the R-407C PT Chart
The PT chart gives you the saturation pressure for any temperature, and the saturation temperature for any pressure. You use this to calculate superheat and subcooling.
R-407C vs R-22 and R-410A
| Property | R-22 | R-407C | R-410A |
|---|---|---|---|
| Composition | Pure HCFC | HFC Blend (3 components) | HFC Blend (2 components) |
| Temperature Glide | None (azeotrope) | ~10°F (zeotrope) | ~0.3°F (near-azeotrope) |
| Static Pressure at 70°F | 131 PSIG | ~162 (Bub) / 171 (Dew) | 201 PSIG |
| Operating Pressure (high) | ~240 PSIG | ~280 PSIG | ~380 PSIG |
| Oil Required | Mineral / AB | POE (must flush) | POE |
| Drop-in for R-22 | — | Partial (needs oil change) | No — different pressures |
| Superheat Reference | Single point | Dew point only | Single point |
Key things to remember about R-407C
- R-407C is a zeotropic blend with ~10°F temperature glide. It has two saturation points — bubble and dew — at every pressure.
- Always use DEW point pressure for superheat calculations on the suction side.
- Always use BUBBLE point pressure for subcooling calculations on the liquid side.
- R-407C must be charged as liquid from the cylinder. Vapor charging causes fractionation and incorrect refrigerant composition.
- R-407C requires POE oil. When retrofitting from R-22, the system must be flushed to remove mineral oil.
- Target superheat for TXV systems: 8–12°F. For fixed orifice: 10–20°F.
- Target subcooling: 8–14°F for most systems. Always verify with manufacturer specification.
- R-407C operates at higher pressures than R-22 but lower than R-410A. Existing R-22 equipment must be checked for compatibility before retrofitting.
Frequently Asked Questions
❄️ R407C PT Chart Calculator
Find bubble and dew temperatures or pressures for this zeotropic blend
🔧 Pressure (psig)
Gauge pressure (psig)
⇄
🌡️ Temperature (°F)
Saturation temperature
📊 PRESSURE-TEMPERATURE METER
0 psig / 0°F
💡 R-407C has a temperature glide of about 8-12°F. Bubble point is for liquid; dew point is for vapor.
⚡ R-407C is non-flammable (A1). For subcooling, use bubble point. For superheat, use dew point.
How to Use This R407C PT Chart Calculator
It is very simple.
To find saturation temperatures (bubble and dew): Type the pressure in psig. The calculator shows the corresponding temperature and the bubble and dew points.
To find saturation pressure: Type the temperature in °F. The calculator shows the corresponding pressure.
To swap values: Click the swap button (⇄) between the boxes.
Understanding Bubble and Dew Points
R-407C is a zeotropic blend. When it evaporates or condenses, the composition changes. This creates a temperature glide of about 8-12°F .
Bubble Point (Liquid):
The temperature at which the first bubble of vapor forms when heating a liquid. Use the bubble point for subcooling calculations .
Dew Point (Vapor):
The temperature at which the first drop of liquid forms when cooling a vapor. Use the dew point for superheat calculations .
Example: At 100 psig, the bubble point is about 65°F and the dew point is about 75°F. The glide is 10°F. For subcooling, use 65°F. For superheat, use 75°F.
R407C PT Chart (Quick Reference)
| Temperature (°F) | Bubble Pressure (psig) | Dew Pressure (psig) | Glide (°F) |
|---|---|---|---|
| 0 | 55 | 72 | 8 |
| 10 | 84 | 102 | 8 |
| 20 | 120 | 140 | 9 |
| 30 | 164 | 186 | 9 |
| 40 | 217 | 242 | 10 |
| 50 | 280 | 307 | 11 |
| 60 | 355 | 384 | 11 |
| 70 | 443 | 474 | 12 |
| 80 | 545 | 578 | 12 |
R-407C Operating Pressures
| System Type | Low Side (psig) | Low Side Temp (°F) | High Side (psig) | High Side Temp (°F) |
|---|---|---|---|---|
| AC (85°F outdoor) | 80-100 | 35-45 | 200-250 | 85-95 |
| AC (95°F outdoor) | 90-120 | 40-50 | 250-300 | 95-105 |
| AC (105°F outdoor) | 100-130 | 45-55 | 300-350 | 105-115 |
R-407C pressures are similar to R-22 .
Superheat Calculation with R-407C
For R-407C, use the dew point for superheat calculations.
Superheat = Suction Line Temp – Dew Point Temp
Example: Suction pressure = 100 psig → dew point = 75°F. Suction line temp = 85°F.
Superheat = 85 – 75 = 10°F (good range for TXV systems).
Subcooling Calculation with R-407C
For R-407C, use the bubble point for subcooling calculations .
Subcooling = Bubble Point Temp – Liquid Line Temp
Example: Liquid pressure = 250 psig → bubble point = 95°F. Liquid line temp = 90°F.
Subcooling = 95 – 90 = 5°F.
Special Note: R-407C requires TWO different PT tables. One for subcooling (liquid) and one for superheat (vapor) .
R-407C vs. R-22
| Property | R-22 | R-407C |
|---|---|---|
| GWP | 1,810 | 1,774 |
| Safety | A1 | A1 |
| Glide | 0 | 8-12°F |
| Composition | Pure | Zeotropic blend |
| Oil Compatibility | Mineral oil | POE oil |
Retrofitting R-22 to R-407C: You must change the oil to POE. R-407C is not miscible with mineral oil .
Frequently Asked Questions (FAQs)
1. What is the composition of R-407C?
23% R-32, 25% R-125, and 52% R-134a .
2. What is the GWP of R-407C?
1,774 (AR4) .
3. Why does R-407C have a temperature glide?
Because it is a zeotropic blend. The composition changes during evaporation and condensation .
4. What is the bubble point of R-407C?
The temperature at which the first bubble of vapor forms. Use it for subcooling calculations .
5. What is the dew point of R-407C?
The temperature at which the first drop of liquid forms. Use it for superheat calculations .
6. What oil is used with R-407C?
POE (Polyolester) oil. Mineral oil is not compatible .
7. Can I use R-407C in a system with a flooded evaporator?
R-407C is not recommended for flooded evaporators due to its high glide .
8. What is the temperature glide of R-407C?
Approximately 8-12°F .
Common Mistakes
Mistake #1: Using the wrong saturation temperature
For subcooling, use the bubble point. For superheat, use the dew point .
Mistake #2: Using the same PT chart as R-22
R-407C has a different PT curve. It is similar but not identical .
Mistake #3: Using mineral oil
R-407C requires POE oil. Mineral oil will not circulate properly .
Mistake #4: Ignoring the glide
When charging R-407C, the glide affects superheat and subcooling readings.
Final Thoughts
R-407C is a common R-22 replacement in air conditioning systems. Its zeotropic nature requires careful attention to bubble and dew points.
My R407C PT Chart Calculator gives you:
- Bubble and dew point data
- Guidance on which to use for superheat vs. subcooling
- R-407C safety and oil compatibility notes
Bookmark this page. Use it when servicing R-22 retrofits.
The next time you need to check R-407C pressures, you will know which temperature to use.
Disclaimer: This is an educational tool based on Arkema and Copeland PT data. Always verify with the manufacturer’s nameplate and follow all safety guidelines.
External Links (Authority Backlinks):
- Wikipedia – R-407C{:target=”_blank” rel=”noopener noreferrer”}
- Wikipedia – Zeotropic mixture{:target=”_blank” rel=”noopener noreferrer”}
- Wikipedia – Refrigerant{:target=”_blank” rel=”noopener noreferrer”}
- Arkema – Forane 407C{:target=”_blank” rel=”noopener noreferrer”}
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