9.1 What Type II Covers: High-Pressure System Overview

What Type II Certification Authorizes

Type II certification authorizes a technician to service, maintain, repair, and dispose of high-pressure and very high-pressure appliances — by far the largest slice of the HVAC/R field. If you work on central air conditioning, heat pumps, rooftop units, walk-in coolers, or a supermarket refrigeration rack, you need Type II. Because these systems are everywhere, the Type II section of the EPA Section 608 exam is the one most candidates spend the most time on, and the one whose rules you will use almost every working day.

The EPA categorizes appliances not by their size but by the operating pressure of the refrigerant they contain. The dividing line is the refrigerant's boiling point at one atmosphere (standard atmospheric pressure, ~14.7 psia). A refrigerant that boils at a very low temperature exerts a very high vapor pressure at room temperature, which is exactly why it is classified as high- or very high-pressure. This single idea — colder boiling point means higher operating pressure — is the conceptual key to the whole Type II section.

How EPA Defines the Pressure Categories

Notice that medium-pressure equipment (such as some R-134a chillers) is serviced under Type II, not a separate certification — there is no "Type medium." Only the low-pressure category, where the refrigerant boils above room temperature and the appliance operates in a vacuum, falls under Type III. The exam frequently tests this boundary, so anchor on the boiling-point thresholds rather than trying to memorize equipment lists.

Equipment Covered by Type II

Type II authorizes work on the following stationary systems:

Residential and light commercial:

• Central air conditioning — split systems and packaged units
• Air-source and ground-source (geothermal) heat pumps
• Ductless mini-split and multi-split systems
• Packaged terminal air conditioners and heat pumps (PTAC / PTHP)

Commercial and industrial:

• Rooftop units (RTUs) and self-contained packaged systems
• Supermarket refrigeration racks and remote condensing units
• Walk-in coolers and freezers with remote compressors
• Reach-in coolers and commercial ice machines that hold more than 5 lbs of refrigerant
• Transport refrigeration on trucks and trailers (the refrigeration unit, not the vehicle cab AC)

What Type II Does NOT Cover

1. Small appliances (5 lbs or less, factory-charged and hermetically sealed) — these are Type I.
2. Motor vehicle air conditioning (MVAC) — covered by Section 609, a separate certification entirely.
3. Low-pressure appliances (centrifugal chillers using R-11 or R-123) — these are Type III because they operate below atmospheric pressure.

Example: A technician is dispatched to a grocery store to repair a leaking R-404A multiplex refrigeration rack holding 320 lbs of refrigerant, then crosses the parking lot to recharge a 4-lb window air conditioner with R-410A, and finally services a 600-ton R-123 centrifugal chiller in the basement. The rack and any unit over 5 lbs require Type II; the window unit (5 lbs or less, self-contained) is a Type I small appliance; and the low-pressure R-123 chiller requires Type III. A technician needs Universal certification to legally touch all three in one day.

Pressure Ranges and Why They Matter

The practical reason pressure category matters is that higher operating pressure changes how you recover, evacuate, and service the system. Very high-pressure R-410A systems run at roughly double the pressure of an older R-22 system, which means recovery machines, hoses, gauges, and recovery cylinders must all be rated for the higher pressure. Using R-22-era equipment on R-410A is both unsafe and a likely cause of equipment rupture.

R-410A vs. R-22 — The Core Comparison

For the Exam: R-410A operates at roughly 60% higher pressure than R-22. You may not assume R-22 recovery equipment is rated for R-410A — verify the pressure rating. R-410A systems use hygroscopic POE oil, so minimize the time the system is open to atmosphere. Both are A1 (lower toxicity, non-flammable), but the newer A2L replacements (R-454B, R-32) are mildly flammable and require updated handling.

The A2L Transition Within Type II

Under the AIM Act's technology-transition rules, new residential and commercial AC and heat pump equipment manufactured after January 1, 2025 must use refrigerant with a GWP of 700 or less, which eliminates R-410A (GWP 2,088) from new systems. The replacements — R-454B (GWP 466) and R-32 (GWP 675) — are both A2L (lower toxicity, mildly flammable) and remain firmly in the high-pressure Type II category.

Critically, no new federal certification is required: an existing Type II or Universal credential authorizes A2L service. What changes is the safety procedure — charge limits, leak-detection sensors, and spark-source precautions per UL 60335-2-40. Recall too that existing R-410A and R-22 systems are not banned; they may be serviced, repaired, and recharged for their full service life.