Introduction: Why Choosing the Right Refrigerant & Pressure Switch Matters
Selecting the right HVAC refrigerant is crucial for HVAC system performance, safety, and environmental compliance. But each gas has different pressure-temperature behavior, so pressure switches must be matched to your refrigerant for proper protection.
This guide covers:
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The full list of refrigerants in HVAC (including discontinued types)
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Typical low and high pressure ranges
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Pressure switch selection tips (with buying links)
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Reference tables for engineers, contractors, and students
Complete List of HVAC Refrigerant Gases (2025 Edition)
| Refrigerant | Status | Main Application | GWP | Ozone Impact | Typical Low Side (bar/psi) | Typical High Side (bar/psi) |
|---|---|---|---|---|---|---|
| R22 | Discontinued | Old AC, chillers | 1810 | Medium | 3–5 / 45–75 | 12–19 / 175–275 |
| R410A | Phasing Down | Modern AC, Heat Pump | 2088 | Zero | 6–9 / 87–130 | 20–32 / 290–460 |
| R407C | Transitional | R22 Retrofit, AC | 1774 | Zero | 3–7 / 45–100 | 13–25 / 190–360 |
| R134a | Being Phased Down | Car AC, Chillers | 1430 | Zero | 2–4 / 29–58 | 9–16 / 130–230 |
| R404A | Discontinued | Commercial Refrigeration | 3922 | Zero | 2–4 / 29–58 | 16–23 / 230–330 |
| R32 | Current | New Gen AC | 677 | Zero | 4–8 / 58–116 | 17–31 / 250–450 |
| R1234yf | Current | Automotive, Eco | <1 | Zero | 2–4 / 29–58 | 7–18 / 100–260 |
| R290 | Current | Hydrocarbon/Green | 3 | Zero | 0.5–2.5 / 7–36 | 10–14 / 145–200 |
| R600a | Current | Domestic Fridges | 3 | Zero | 0.2–1.5 / 3–22 | 4–6 / 60–87 |
| R12 | Discontinued | Old Car AC, Fridges | 10,900 | Very High | 1.5–2.5 / 22–36 | 9–14 / 130–200 |
| R502 | Discontinued | Old Freezers, Commercial | 4657 | Very High | 1.5–2.5 / 22–36 | 14–22 / 200–320 |
| R717 (Ammonia) | Current | Industrial/Cold Store | 0 | Zero | 1–5 / 14–72 | 9–20 / 130–290 |
| R744 (CO₂) | Current | Supermarket, Transport | 1 | Zero | 20–45 / 300–650 | 45–110 / 650–1600 |
Key:
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GWP: Global Warming Potential
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Ozone Impact: Indicates ODP risk—high for old CFC/HCFCs
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Discontinued: Banned or phased out in new equipment
References: ASHRAE Handbook, Engineering Toolbox – Refrigerants, Danfoss PT Chart PDFs, EPA Snap List, Honeywell Refrigerant Guide.
Understanding Pressure Ranges: Why They Differ
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High-pressure refrigerants (R410A, R404A, R32, CO₂) require components (valves, pressure switches, hoses) rated for much higher pressure.
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Medium/low-pressure refrigerants (R22, R134a, R1234yf, R717) have safer, more moderate requirements.
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Discontinued CFCs (R12, R502): included for reference only.
Pressure Switch Selection Guide (by Refrigerant)
| Refrigerant | LP Cut-Out (bar/psi) | HP Cut-Out (bar/psi) | Check on Amazon |
|---|---|---|---|
| R410A | 3–4 / 44–58 | 38–42 / 550–610 | Danfoss KP15 |
| R22/R407C | 1.5–2.5 / 22–36 | 22–25 / 320–360 | Johnson P100 |
| R134a | 1–2 / 15–29 | 18–20 / 260–290 | Danfoss KP5 |
| R404A | 1–2 / 15–29 | 26–30 / 377–435 | Danfoss KP5 |
| R32 | 3–4 / 44–58 | 38–42 / 550–610 | Johnson P100 |
| R290 | 0.5–1 / 7–15 | 18–20 / 260–290 | Danfoss KP1 |
| R600a | 0.2–0.5 / 3–7 | 8–10 / 116–145 | Danfoss KP1 |
| R717 | 1–2 / 15–29 | 20–25 / 290–360 | Johnson P77 |
| R744 (CO₂) | 20–40 / 300–580 |
70–110 / 1000–1600 |
Tip: Always select a pressure switch with a maximum rating higher than the refrigerant’s possible pressure. Never use a switch rated for R22 on an R410A system.
Product Buying Guide (Pressure Switches)
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Danfoss KP Series: Shop on Amazon
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Johnson Controls P100/P77 Series: Shop on Amazon
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Bulk/Generic: Find on AliExpress
Real-World Example
Example: For an R410A air conditioner, the high-pressure switch should cut out at 600 psi (42 bar) and the low-pressure switch at about 45 psi (3 bar).
For an R134a chiller, cut-outs are usually 250–290 psi (18–20 bar) high and 20 psi (1.3 bar) low.
