8.1 High-Pressure System Overview
Key Takeaways
- Type II covers high-pressure and very high-pressure systems — the most common in the field
- R-410A operates at ~60% higher pressure than R-22 — equipment must be rated accordingly
- R-410A uses POE oil (hygroscopic); R-22 uses mineral oil
- Type II does NOT cover small appliances (Type I), MVAC (Section 609), or low-pressure chillers (Type III)
- R-454B and R-32 (both A2L) are replacing R-410A in new equipment
8.1 High-Pressure System Overview
Type II certification covers high-pressure and very high-pressure appliances — the most commonly encountered systems in the HVAC/R field. These include residential and commercial air conditioning, heat pumps, and commercial refrigeration equipment.
System Categories
EPA categorizes systems by their operating pressure:
| Category | Boiling Point | Examples of Refrigerants | Common Equipment |
|---|---|---|---|
| Very High-Pressure | Below -50°F | R-410A, R-507A | Modern residential AC, heat pumps |
| High-Pressure | Between -50°F and 10°F | R-22, R-404A, R-134a, R-407C | Legacy AC, commercial refrigeration |
| Medium-Pressure | Between 10°F and 50°F | R-134a, R-500 | Chillers, automotive (non-MVAC) |
| Low-Pressure | Above 50°F | R-11, R-123 | Centrifugal chillers (Type III) |
Equipment Covered by Type II
Type II certification authorizes technicians to work on:
Residential Systems:
- Central air conditioning (split systems and packaged units)
- Heat pumps (air-source and ground-source)
- Mini-split (ductless) systems
- Packaged terminal heat pumps (PTHP)
Commercial Systems:
- Rooftop units (RTUs)
- Supermarket refrigeration systems
- Walk-in coolers and freezers (with remote compressors)
- Restaurant refrigeration
- Commercial ice machines (above 5 lbs charge)
- Reach-in coolers (above 5 lbs charge)
- Transport refrigeration (truck/trailer systems)
What Type II Does NOT Cover:
- Small appliances (Type I)
- Motor vehicle air conditioning — MVAC (Section 609)
- Low-pressure centrifugal chillers (Type III)
Key Refrigerants for Type II
| Refrigerant | Category | Pressure at 70°F | Status | Common Application |
|---|---|---|---|---|
| R-22 | High-pressure | ~121 psig | No new production since 2020 | Legacy residential/commercial AC |
| R-410A | Very high-pressure | ~201 psig | Being phased out of new equipment | Residential AC, heat pumps |
| R-404A | High-pressure | ~175 psig | Major phasedown target | Commercial refrigeration |
| R-407C | High-pressure | ~133 psig | Retrofit replacement for R-22 | Commercial AC |
| R-134a | Medium-pressure | ~70 psig | Being replaced | Chillers, some commercial |
| R-454B | High-pressure | ~165 psig | Replacing R-410A (A2L) | New residential/commercial AC |
| R-32 | High-pressure | ~175 psig | Replacing R-410A (A2L) | New residential/commercial AC |
R-410A vs. R-22: Key Differences
Understanding the differences between R-410A and R-22 is critical for Type II technicians:
| Property | R-22 | R-410A |
|---|---|---|
| Operating pressure | ~121 psig at 70°F | ~201 psig at 70°F |
| Pressure ratio | Baseline | ~60% higher than R-22 |
| ODP | 0.055 | 0 |
| GWP | 1,810 | 2,088 |
| Oil type | Mineral or AB | POE (polyolester) |
| Safety class | A1 | A1 |
| Current status | No new production | Being phased out of new equipment |
| Charging method | Liquid or vapor | Liquid (manufacturer recommendation) |
For the Exam: R-410A operates at significantly higher pressures than R-22 (~60% higher). You CANNOT use R-22 equipment (gauges, hoses, recovery machines) for R-410A without verifying it is rated for the higher pressures. R-410A uses POE oil; R-22 uses mineral oil.
R-410A operates at approximately what percentage higher pressure than R-22?
Which type of oil is required for R-410A systems?
Which of the following systems is NOT covered by Type II certification?