EPA 608 Certification Study Guide By Mike Westmoreland — 30+ Years HVAC Experience
Everything you need to pass all four sections of the EPA 608 Universal exam on your first attempt. Written by a working HVAC technician with over 30 years in the field — not a textbook publisher.
Covers Core, Type I, Type II & Type III
Updated for 2026 — includes AIM Act & A2L refrigerant content most guides miss
40 interactive practice questions with instant answers & explanations
Visual diagrams — refrigeration cycle, recovery levels, refrigerant chart
The exact numbers, dates, and rules the exam tests
Written in plain language — no experience required to understand it
Once you pass, your certification never expires. This guide gets you there.
EPA 608
UNIVERSAL
Everything you need to pass all four sections of the EPA Section 608 Universal exam — Core, Type I, Type II, and Type III — including the latest AIM Act regulations and A2L refrigerant updates effective January 2025.
Under Section 608 of the Clean Air Act and 40 CFR Part 82, Subpart F, any technician who maintains, services, repairs, or disposes of equipment containing refrigerants must be certified. Working without certification is a federal violation. You cannot legally purchase refrigerant in containers over 20 lbs without it.
| Section | Questions | To Pass | Format | Difficulty |
|---|---|---|---|---|
| Core | 25 | 18 (72%) | Proctored / Closed Book | ⚠ Most Failed |
| Type I | 25 | 21 (84%) | Open Book Allowed | ✓ Easier |
| Type II | 25 | 18 (72%) | Proctored / Closed Book | ✗ Highest Fail Rate |
| Type III | 25 | 18 (72%) | Proctored / Closed Book | ⚠ Counterintuitive |
If you want Universal Certification, your Core exam MUST be taken as a proctored exam — even if you already passed an open-book Core for Type I separately. Plan a single proctored sitting that covers Core + I + II + III. Approved providers: ESCO Institute, Mainstream Engineering, HVAC Excellence.
As of January 1, 2025, no new R-410A can be manufactured or imported into the US. New residential and light-commercial systems now use A2L refrigerants (R-454B, R-32). Exam questions now cover A2L handling, safety, and the AIM Act phasedown schedule. Any study guide from before 2024 is missing this content.
The Core exam is required for all certification types. It covers environmental law, refrigerant regulations, recovery/recycling/reclamation, and safety. Most technicians fail Core because they underestimate it. 80% of Core questions are regulatory definitions and dates — memorize them exactly.
The Clean Air Act & Section 608
Section 608 of the Clean Air Act prohibits the knowing venting of refrigerants and requires certification for anyone who handles them commercially. This is federal law — it applies in all 50 states with no exceptions for experience level.
- July 1, 1992 — Venting prohibition takes effect for CFCs and HCFCs (R-12, R-22, etc.)
- November 15, 1995 — Venting prohibition extended to HFCs (R-410A, R-134a, R-404A)
- $44,539 per day per violation — Current federal civil penalty (40 CFR 82.169). This exact number is tested.
- 0.1 ounce — De minimis exemption. The ONLY quantity-based exception to recovery requirements.
- January 1, 2025 — No new R-410A manufactured or imported (AIM Act)
- AIM Act target: 85% HFC phasedown by 2036
The Three R's — Recovery, Recycling, Reclamation
| Process | What It Means | Purity Standard | Location |
|---|---|---|---|
| Recovery | Removing refrigerant from a system and storing it in an approved cylinder | None required at removal | On-site (field) |
| Recycling | Cleaning refrigerant using filter-driers and oil separation | Does NOT meet ARI-700 | On-site (field) |
| Reclamation | Reprocessing refrigerant to ARI-700 purity standards — required before resale | Must meet ARI-700 | EPA-certified facility only |
Reclamation cannot be performed in the field. It must be done at an EPA-certified reclamation facility. This is frequently tested. On-site recycling with filter-driers does NOT qualify as reclamation.
Refrigerant Classifications
Highest ODP
Banned from production
Venting prohibited July 1, 1992
Lower ODP than CFCs
R-22 production ended 2020
Venting prohibited July 1, 1992
Zero ODP but high GWP
AIM Act phasedown began 2022
Venting prohibited Nov 15, 1995
Replace R-410A
ASHRAE Standard 34 Class A2L
Now on the exam — study these
Industrial use
Safety hazards vary by type
The exam often asks which class R-22 belongs to. Many technicians guess Class I because R-22 is "old." Wrong — R-22 is Class II (HCFC). Class I = CFCs only (R-11, R-12). This is one of the highest-miss questions on the Core exam.
Leak Rate Thresholds
| Equipment Type | Annual Leak Rate Trigger | Repair Timeline |
|---|---|---|
| Comfort Cooling (residential/commercial AC) | 10% | 30 days |
| Commercial Refrigeration | 20% | 30 days |
| Industrial Process Refrigeration | 35% | 30 days |
Safety Essentials
- Never use oxygen to pressurize a system — explosive risk. Always use dry nitrogen for leak testing.
- Refrigerant cylinders must never exceed 80% liquid capacity and must be DOT-approved.
- Cylinders must never exceed 130°F — this is a tested safety fact.
- Refrigerant can displace oxygen in enclosed spaces — always ventilate before working.
- Mixing refrigerants is prohibited — cross-contamination creates a non-reclaimable waste refrigerant.
Type I covers appliances manufactured and charged with 5 lbs or less of refrigerant. Examples include household refrigerators, window air conditioners, packaged terminal ACs (PTACs), and most portable ACs. Type I is the only section that may be taken online in open-book format.
The 5-lb cutoff is based on the original manufactured charge, not the current charge. Even if refrigerant has leaked and the system only holds 3 lbs right now, if it was manufactured with 6 lbs — it is a Type II appliance, not Type I.
- 90% efficiency — Required when recovery equipment IS running (compressor-based recovery)
- 80% efficiency — Required when recovery equipment motor is NOT running (passive recovery)
- Recovery equipment manufactured after November 15, 1993 must meet these efficiency standards
- For pre-1993 equipment: recovery to 4 inches Hg vacuum
- Process stub — A small appliance that uses a process stub for service does not need a service port
Type I Specific Rules
| Topic | Rule |
|---|---|
| System charge size | ≤ 5 lbs manufactured charge |
| Recovery — equipment running | 90% recovery efficiency |
| Recovery — motor off | 80% recovery efficiency |
| Exam format | Open-book allowed (Type I only) |
| Pass threshold | 21 out of 25 (84%) — higher than other sections |
| Common refrigerants | R-134a, R-12 (older units), R-600a (isobutane) |
Type II is the most common certification and has the highest fail rate. It covers high- and very-high-pressure appliances including residential split systems, heat pumps, rooftop units, and commercial walk-in coolers. Most HVAC field technicians need Type II or Universal.
The majority of Type II failures come from technicians who memorized only R-22 data and skipped A2L refrigerants. Since January 2025, exam questions now specifically cover R-454B, R-32, and the AIM Act transition. If your study guide predates 2024, you have gaps.
- 10 inches Hg vacuum — Required for systems with less than 200 lbs of refrigerant (post-1993 equipment)
- 15 inches Hg vacuum — Required for systems with 200 lbs or more of refrigerant
- Leak rates: 10% comfort cooling / 20% commercial refrigeration / 35% industrial process
- R-410A operating pressure: ~400 psig on high side — much higher than R-22 (~250 psig)
- R-454B (Puron Advance / Opteon XL41) — primary R-410A replacement under AIM Act
- R-32 — also replacing R-410A in new equipment, used in mini-splits
Recovery Requirements — Type II
| Equipment Manufacture Date | System Size | Recovery Requirement |
|---|---|---|
| Before November 15, 1993 | Any size | 0 psig (atmospheric) |
| After November 15, 1993 | Less than 200 lbs | 10 inches Hg vacuum |
| After November 15, 1993 | 200 lbs or more | 15 inches Hg vacuum |
| Very high pressure (R-410A) | Any size | 0 psig (can't pull a vacuum) |
A2L Refrigerants — 2026 Exam Content
| Refrigerant | Replaces | Classification | GWP | Notes |
|---|---|---|---|---|
| R-454B (Puron Advance) | R-410A | A2L (mildly flammable) | 466 | Primary residential replacement |
| R-32 | R-410A | A2L (mildly flammable) | 675 | Common in mini-splits |
| R-455A | R-410A | A2L (mildly flammable) | 148 | Carrier systems (Vantage) |
| R-410A | (being phased out) | A1 (non-flammable) | 2,088 | No new production as of Jan 2025 |
| R-22 | (phased out) | A1 (non-flammable) | 1,810 | Production ended 2020 |
A2L refrigerants are mildly flammable (ASHRAE Standard 34 Class A2L — burning velocity ≤10 cm/s, LFL >3.5% by volume). Standard A1-rated recovery machines used for R-410A are NOT certified for A2L refrigerants. You need A2L-rated recovery equipment. Also: Do NOT add R-32 or R-454B to an R-410A system — these are not drop-in replacements. Mixed refrigerant = non-reclaimable waste.
Leak Detection Methods
- Electronic leak detectors — Most sensitive, can detect 0.1 oz/year or less
- Fluorescent dye — Injected into system, detected with UV light. Long-term leak tracing.
- Soap bubbles — Simple, effective for large leaks. Not for small or internal leaks.
- Nitrogen pressure test — Used for dry pressure testing. Never use oxygen or refrigerant gas alone for testing.
- Ultrasonic detectors — Detect sound of refrigerant escaping under pressure.
Type III covers low-pressure centrifugal chillers — large commercial/industrial systems that operate below atmospheric pressure (in a vacuum). These are common in large office buildings, hospitals, and industrial facilities. The physics are counterintuitive: when a low-pressure system leaks, air leaks IN, not refrigerant out.
High-pressure systems (Type II) lose refrigerant when they leak. Low-pressure systems (Type III) gain air and moisture when they leak because they operate below atmospheric pressure. This is the #1 conceptual mistake on Type III. Air infiltration causes freeze-up risk in the evaporator.
- 25 mm Hg absolute pressure — Recovery standard for post-1993 low-pressure equipment. Deepest vacuum requirement of all sections.
- Dry nitrogen only — For leak testing low-pressure systems. Never use refrigerant gas for pressurization.
- Purge units — Remove non-condensables (air, moisture) that infiltrate through leaks. Purge units vent small amounts — this IS permitted under EPA rules for low-pressure systems.
- Freezing risk — Water in the evaporator can freeze at low pressures, potentially cracking the tubes.
- Common refrigerants: R-11 (CFC, phased out), R-123 (HCFC), R-245fa
Type III Recovery Standards
| Equipment Date | Recovery Level |
|---|---|
| Pre-1993 equipment | 25 mm Hg absolute pressure |
| Post-1993 equipment | 25 mm Hg absolute pressure |
| If recovery equipment fails | Isolate refrigerant charge, evacuate to 25 mm Hg before repair |
Purge Unit Operation
Low-pressure systems use purge units to expel non-condensables that accumulate from air infiltration. Modern high-efficiency purge units capture and recover refrigerant that would otherwise be vented. Purge unit emissions are regulated — high-efficiency units required on newer systems.
This chart covers the refrigerants most commonly tested on the EPA 608 exam. Memorize the pressure-temperature relationships and key properties for R-22, R-410A, and the new A2L refrigerants.
| Refrigerant | Type | Class | ODP | GWP | Use | Status 2026 |
|---|---|---|---|---|---|---|
| R-11 | CFC | A1 | 1.0 (reference) | 4,750 | Low-press chillers | Banned |
| R-12 | CFC | A1 | 1.0 | 10,900 | Old auto AC, refrigerators | Banned |
| R-22 | HCFC | A1 | 0.055 | 1,810 | Older residential AC | No new production 2020 |
| R-123 | HCFC | B1 | 0.02 | 77 | Centrifugal chillers | Still available |
| R-134a | HFC | A1 | 0 | 1,430 | Auto AC, chillers | Phasedown |
| R-404A | HFC blend | A1 | 0 | 3,922 | Commercial refrigeration | Phasedown |
| R-410A | HFC blend | A1 | 0 | 2,088 | Residential AC (legacy) | No new production Jan 2025 |
| R-454B | HFO blend | A2L | 0 | 466 | Residential AC (new) | Primary R-410A replacement |
| R-32 | HFC | A2L | 0 | 675 | Mini-splits | Growing use |
| R-717 | Natural (Ammonia) | B2L | 0 | 0 | Industrial refrigeration | Active use |
| R-744 | Natural (CO₂) | A1 | 0 | 1 | Transcritical systems | Growing use |
As pressure increases, boiling point increases. As pressure decreases, boiling point decreases. This is the fundamental principle behind how refrigeration systems work. R-410A operates at roughly 70% higher pressure than R-22 — gauges, hoses, and equipment rated for R-22 are NOT safe for R-410A. Always verify equipment ratings before use.
40 exam-style questions covering all four sections. Click an answer to see if you're right and read the explanation. Your score updates in real time.