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EPA 608 Certification Prep

Module 6: Type II - High-Pressure Systems

Type II Certification -- Module 6 of 7

Type II Equipment: Definition and Scope

Type II certification covers high-pressure refrigerant systems containing more than 5 pounds of refrigerant. This covers residential and commercial AC, heat pumps, and commercial refrigeration -- the bulk of HVAC work in the United States. "High-pressure" means the refrigerant's saturation pressure is above atmospheric at typical operating temperatures. Unlike low-pressure systems (Type III) that operate under vacuum, every point in a high-pressure circuit is under positive pressure.

>5 lbs

Charge threshold

Minimum for Type II

800 psig

R-410A equipment

Minimum pressure rating

30%

Leak threshold

Repair required (50+ lb systems)

Jan 2025

R-410A ban

New equipment only

High-Pressure Refrigerant Reference Table

Refrigerant	Class	GWP	Application	Status
R-22	HCFC	1,810	Residential/commercial AC (legacy)	Virgin production banned 2020; reclaimed only
R-410A	HFC blend	2,088	Residential/commercial AC (current)	New equipment ban Jan 2025; servicing continues
R-454B	HFO/HFC blend	466	New residential AC (2025+)	A2L; primary R-410A replacement
R-32	HFC	675	Mini-splits, some commercial	A2L; growing adoption
R-134a	HFC	1,430	Medium-temp commercial refrigeration, HFC chillers	Active
R-404A	HFC blend	3,922	Commercial and transport refrigeration	Being replaced due to very high GWP
R-407C	HFC blend	1,774	R-22 retrofit systems	Active; common R-22 replacement

Required Evacuation Levels for Type II Systems

System Charge Size	Built Before 11/15/1993	Built After 11/15/1993
Less than 200 lbs	0 psig (atmospheric)	0 psig (atmospheric)
200 lbs or more	4 inches Hg vacuum	10 inches Hg vacuum

R-410A: Critical Knowledge for Type II Technicians

R-410A operates at 50-70% higher pressures than R-22 at the same temperatures. At 77 degrees F, an R-410A cylinder sits at approximately 210-220 psig vs R-22 at 121-131 psig. Always use manifold gauges and hoses specifically rated for R-410A -- minimum 800 psig working pressure. Never use R-22 equipment (typically rated only 500-600 psig) for R-410A.

Zeotropic Blend and Liquid Charging -- Exam Critical

R-410A is a zeotropic (near-azeotropic) blend of R-32 (50%) and R-125 (50%). These components have different boiling points. If charged as vapor, the lighter component (R-32) exits the cylinder first -- this is called fractionation, which changes the blend composition in both the cylinder and the system.

R-410A Must Always Be Charged as LIQUID

Vapor charging causes fractionation, altering the refrigerant composition and degrading system performance. Always charge R-410A from an inverted cylinder to deliver liquid. This applies to all zeotropic blends: R-407C, R-404A, R-454B. Single-component refrigerants like R-22, R-32, and R-134a can be charged as either vapor or liquid.

Oil Type: POE Required

R-410A systems require POE (polyolester) oil. POE is hygroscopic (absorbs moisture readily) -- keep containers tightly sealed. Never use mineral oil in R-410A systems -- it is immiscible with R-410A and will not circulate properly, causing lubrication failure and compressor damage.

Retrofit Refrigerants for R-22 Systems

Rules for all R-22 retrofits:

ALL existing R-22 must be completely recovered before introducing replacement refrigerant
Never mix refrigerant types -- mixing creates contaminated blends requiring reclaim
Update the equipment label with new refrigerant type, charge amount, and conversion date
Replace filter-drier with appropriate unit for the new refrigerant

Retrofit Refrigerant	Oil Compatibility	TXV Change?	Notes
R-407C	POE required (flush mineral oil)	Usually yes	Most common; closest performance to R-22
R-422D (MO99)	Mineral oil compatible	Usually no	Near-drop-in; convenient for older systems
R-438A (MO89)	Mineral oil compatible	Usually no	Compatible with existing mineral oil

R-454B: The Future of Residential HVAC

Starting January 1, 2025, new residential and light-commercial HVAC equipment must use refrigerants with GWP below 700. R-454B is the primary replacement:

GWP: 466 -- 78% lower than R-410A
A2L classification -- mildly flammable; requires A2L-specific equipment
Similar operating pressures to R-410A
Requires POE oil
Existing R-410A equipment can still be serviced with R-410A indefinitely

Common Diagnostic Symptoms

Symptom	Likely Cause(s)
High discharge pressure	Dirty/blocked condenser, overcharge, non-condensables (air) in system, poor airflow
Low suction pressure	Refrigerant undercharge (leak), restricted TXV or metering device, dirty filter-drier
High suction pressure	Overcharge, failed TXV (wide open), failed compressor valves, high load condition
Short cycling	Low charge, faulty pressure switch, low airflow, oversized equipment

Exam Memory Aid: R-410A Key Facts

Pressure: 50-70% higher than R-22 -- use 800+ psig rated equipment
Charging: Liquid only (inverted cylinder) -- vapor causes fractionation
Oil: POE only (not mineral oil)
GWP: 2,088 -- replaced by R-454B (GWP 466) in new equipment 2025+
Blend: R-32 (50%) + R-125 (50%) -- zeotropic, must charge as liquid

Module 6 Key Terms

Zeotropic Blend

Refrigerant mixture whose components have different vapor pressures and boiling points. Exhibit temperature glide and must be charged as liquid to prevent fractionation. R-410A, R-407C, and R-404A are zeotropic blends.

Fractionation

Separation of zeotropic blend components during vapor charging. The lighter, more volatile component leaves the cylinder first, altering the mix ratio. Prevented by charging as liquid from an inverted cylinder.

POE Oil (Polyolester)

Synthetic lubricant required for HFC refrigerants (R-410A, R-134a, R-454B). Highly hygroscopic -- absorbs moisture readily; must be kept sealed. Never use mineral oil with HFC refrigerants.

Non-Condensables

Gases (primarily air) that do not condense at the system's condensing temperature. Cause elevated head pressure and reduced efficiency. Introduced by inadequate evacuation before charging. Air in the system is a technician error.

R-454B (Opteon XL41)

HFO/HFC blend replacing R-410A in new equipment after January 2025. GWP = 466 (78% lower than R-410A). A2L classified. Similar pressures to R-410A. Requires A2L-rated service equipment.

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