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:
The full list of refrigerants in HVAC (including discontinued types)
Typical low and high pressure ranges
Pressure switch selection tips (with buying links)
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:
GWP: Global Warming Potential
Ozone Impact: Indicates ODP risk—high for old CFC/HCFCs
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
High-pressure refrigerants (R410A, R404A, R32, CO₂) require components (valves, pressure switches, hoses) rated for much higher pressure.
Medium/low-pressure refrigerants (R22, R134a, R1234yf, R717) have safer, more moderate requirements.
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)
Danfoss KP Series: Shop on Amazon
Johnson Controls P100/P77 Series: Shop on Amazon
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.
