EPA 608 Type II Study Guide (High-Pressure Systems)

Type II covers high-pressure and very high-pressure appliances: residential split AC and heat pumps, rooftop units, and most commercial refrigeration. It's the type most HVAC techs need. You also need Core.

Required evacuation levels (memorize this table)

For recovery equipment made after November 15, 1993:

If leaks make the level impossible: isolate the leaking components where possible, evacuate the rest of the system to the required level, and evacuate the leaking part to the lowest level you can reach without pulling in air.

Leak repair

• Applies at 50 lb or more of ozone-depleting refrigerant (Section 608), and since 2026 at 15 lb or more of HFCs under the AIM Act rule.
• Repairs are generally due within 30 days, followed by an initial and a follow-up verification test.

Finding leaks

• Oil at a joint is the classic sign. Refrigerant carries oil out with it.
• Electronic leak detector to find the general area fast; bubbles to pinpoint.
• Standing pressure test with dry nitrogen (never oxygen or air), below the nameplate test pressure.
• A vacuum that won't hold also signals a leak, but doesn't tell you where.

Recovery techniques

• Recover liquid first. It's faster. Then recover the remaining vapor.
• Push-pull moves liquid using vapor pressure from the recovery machine. Don't use it on systems with less than about 15 lb of refrigerant, or where you can't keep a solid liquid column.
• Chill the recovery cylinder to lower its pressure and speed things up.
• Working compressor: much of the charge collects on the high side, so recover from the liquid line or receiver. Dead compressor: recover from both sides.
• Wait after you reach the level. If pressure rises, refrigerant is still boiling out of oil or trapped liquid. Recover again.
• Use a dedicated recovery cylinder for each refrigerant, and clear the recovery machine before switching refrigerants.

Charging

• From a vacuum, charge vapor first to raise the pressure above the point where water would freeze in the evaporator. Then charge liquid into the liquid line.
• Blends with glide (R-407C, R-454B and other zeotropes) are charged as liquid so the blend stays the right mix. Meter liquid slowly if charging into the suction side.
• Charge by the method in the installation instructions: superheat for fixed orifice (piston) systems, subcooling for TXV and EEV systems, or weigh in.

A2L systems

Many new residential systems use R-32 or R-454B (A2L, mildly flammable). Before opening the circuit: recover, evacuate, purge with nitrogen, use A2L-rated tools, and keep ignition sources away. Follow the manufacturer's procedures and any state rules.

System components to know

• Receiver: stores liquid refrigerant after the condenser.
• Reversing valve: lets a heat pump switch between heating and cooling.
• Liquid line and receiver outlet: where you find liquid. Suction line: low-pressure vapor. Discharge line: hot, high-pressure vapor.

Disposal

Before a high-pressure appliance is scrapped, the refrigerant must be recovered to the required level.