A2L Refrigerant Certification Guide: ESCO Low GWP Exam, EPA 40 CFR 84 Rules and UL 60335-2-40
Reviewed by Craig Migliaccio, NJ Master HVACR Contractor & Founder, AC Service Tech ·
A2L refrigerant certification usually means the ESCO Institute HVAC Excellence Low GWP Refrigerant Safety: A2Ls exam, and it matters because EPA's 40 CFR 84 Technology Transitions rule and the SNAP use conditions tied to UL 60335-2-40 now push new AC and heat pump equipment onto mildly flammable refrigerants. This guide covers the exam's cost, format, pass score and study plan, plus the EPA rules behind it, all from ESCO, EPA and eCFR sources.
A2L Refrigerant Safety Practice TestA2L Refrigerant Safety Full Mock Exam
What Is the ESCO A2L Refrigerant Certification Exam?
ESCO Institute runs the HVAC Excellence Specialty Certifications. Its Specialty Certifications page lists the Low GWP Refrigerant Safety: A2Ls (Mildly Flammable) exam, which "addresses the safe handling of A2L (mildly flammable) refrigerants." There is no prerequisite, and students, technicians and instructors can all take it. A separate A3 exam covers highly flammable hydrocarbon refrigerants like propane and isobutane.
The 50-question exam covers five competencies:
- General Flammable Refrigerant Safety Knowledge
- Core ACR Knowledge
- Flammable System Service Safety
- Flammable System Installation Safety
- Flammable Refrigerant Transportation and Handling Safety
ESCO's Low GWP training program explains that many replacement refrigerants "are classified by ASHRAE as A2L, or slightly flammable." Its manual covers refrigerant safety, refrigerant properties, the refrigeration cycle, working with blends, installation and service guidelines, flammable refrigerant considerations, and the codes and standards for A2L refrigerants.
ESCO A2L Exam Cost, Number of Questions and Time Limit
The Virginia CTE Resource Center credential listing gives the testing details for the ESCO A2L exam:
| Item | ESCO A2L exam |
|---|---|
| Number of questions | 50 |
| Time allowed | 120 minutes (minimum); extended time as needed |
| Passing score | 70% (35 of 50) |
| Cost per test | $25 online; $35 paper |
| Format | Closed book; online or paper and pencil |
| Where | A school, the contractor's location or a testing facility with an approved proctor |
The listing notes that a school must have an approved test administrator or proctor, and that ESCO handles extra accommodations by phone.
Is the A2L Exam Open Book? Pass Score and Retakes
No. ESCO calls it a "closed-book exam," so you cannot bring the training manual, UL 60335-2-40 or the EPA rules into the test. You need 70% to pass. The ESCO and CTE pages we checked do not publish a retake policy or waiting period, so ask your proctor or ESCO before you schedule a second attempt.
How Hard Is the A2L Refrigerant Safety Exam?
For a working technician, the hardest part is usually not the refrigeration cycle but the new safety details: label wording, red service-port marking, ventilation, ignition sources and transport. The exam is closed book, so you must memorize numbers like the ¼-inch label letters, the 1-inch red marking and the ¼ LFL evacuation trigger. The 120-minute minimum gives you more than 2 minutes per question, so time is rarely the problem. Recall is.
Why A2L Matters: EPA 40 CFR 84 Technology Transitions Dates
EPA's Technology Transitions rule in 40 CFR Part 84, Subpart B implements the AIM Act. It sets GWP limits by sector. The installation limits that matter most to HVAC technicians are in §84.54(c):
| System installed | Restricted GWP | Effective |
|---|---|---|
| Residential and light commercial AC and heat pumps (not VRF) | 700 or greater | January 1, 2025 |
| Residential and light commercial VRF systems | 700 or greater | January 1, 2026 |
| Chillers for comfort cooling | 700 or greater | January 1, 2025 |
| Remote condensing units (retail food) | 1,400 or greater | July 27, 2026 |
| Data center and computer room cooling | 700 or greater | January 1, 2027 |
A new split system with a GWP-700+ refrigerant may still be installed if all its specified components (condensing units, condensers, compressors, evaporator units and evaporators) were made or imported before January 1, 2025. For VRF, the cutoff for components is January 1, 2026, and installation must happen before January 1, 2027. Separately, §84.54(b) bans sale and distribution of restricted products three years after each manufacture date.
Every covered product, component or system must carry a permanent English label under §84.58 showing the refrigerant's chemical name or ASHRAE designation and the date of manufacture. For a field-charged system, that date is the date of first charge, and the installer completes the label at first charge. An unlabeled system installed after the compliance date is presumed to use a refrigerant above the limit.
EPA SNAP Use Conditions for A2L Refrigerants (UL 60335-2-40)
EPA's SNAP listings in Appendix X to 40 CFR Part 82, Subpart G accept HFC-32, HFO-1234yf, R-452B, R-454A, R-454B and R-454C for chillers and residential dehumidifiers, subject to use conditions. Key conditions:
- New equipment only. No retrofit of equipment designed for another refrigerant.
- Standards. Dehumidifiers must meet UL 60335-2-40 (3rd edition), and chillers must meet ASHRAE 15-2019. Where the two differ, the more stringent condition applies.
- Warning labels. These include "WARNING—Risk of Fire. Flammable Refrigerant Used. To Be Repaired Only By Trained Service Personnel," in letters at least 6.4 mm (¼ inch) high.
- Red service ports. Ports, pipes and hoses are marked in PMS #185 or RAL 3020 red, extending at least 1 inch (25 mm) both ways, and the marking is replaced if removed.
- Nameplate markings. These show minimum installation height (if UL requires it) and minimum room area, both calculated per UL 60335-2-40.
- Ducted equipment. No auxiliary devices that may be ignition sources go in the ductwork unless they are listed for the appliance.
The safety guidance in the same listing is core exam material. Keep a class B dry powder extinguisher nearby, use only spark-proof tools, use recovery equipment designed for flammable refrigerants, and wear chemical goggles and gloves. If refrigerant in the air rises above one-fourth of the lower flammability limit, evacuate and re-enter only after ventilating. Personnel should train on Annex HH of UL 60335-2-40. Clean Air Act section 608(c)(2) bans knowingly venting substitute refrigerants, DOT rules govern transport of flammable gases, and recovered flammable refrigerants are likely RCRA hazardous waste.
The 2024 rule in Appendix Y extends similar conditions to retail food refrigeration, ice machines, industrial process refrigeration, cold storage and ice rinks under UL 60335-2-89 and ASHRAE 15-2022. It also allows the GHS black flame symbol, with the ASHRAE 34-2022 safety class printed next to it.
EPA Leak Repair and Reclaim Rules Under 40 CFR 84 Subpart C
From January 1, 2026, 40 CFR Part 84, Subpart C adds HFC management rules for appliances with 15 or more pounds of refrigerant above GWP 53. Residential and light commercial AC and heat pumps are excluded. Leak rate triggers are 20% for commercial refrigeration, 30% for industrial process refrigeration and 10% for comfort cooling. Repairs are due within 30 days (120 with an industrial shutdown), with initial and follow-up verification tests. Commercial and industrial process refrigeration systems of 1,500 lb or more need automatic leak detection. Reclaimed refrigerant may contain no more than 15% virgin HFC.
A2L Refrigerant Safety Basics From EPA
EPA's Refrigerant Safety page lists refrigerant risks as toxicity, flammability, asphyxiation and physical hazards. It explains that flash point and vapor pressure drive flammability, that the lower and upper flammability limits (LFL and UFL) define the flammable range in air, and that safety classes come from ASHRAE Standard 34. Leak detectors and monitoring systems warn technicians when concentrations rise.
Does Every State Require A2L Certification? State Differences
The federal rules we cite do not create a separate federal A2L license. Instead, Appendix X says only technicians "specifically trained in handling flammable refrigerants" should service this equipment, and Appendix Y reminds companies to "inform themselves of and comply with any other applicable legal obligations." Your state mechanical code, licensing board, local building department or employer may adopt UL 60335-2-40 or ASHRAE 15 requirements, or ask for proof of A2L training. Check with your local authority before you install. EPA 608 rules on recovery and venting still apply. See our EPA 608 Practice Tests and Study Guides.
A2L Refrigerant Certification Study Plan
- Days 1–3: learn the Appendix X labels, red port marking, ¼ LFL rule, extinguisher, tools and recovery equipment.
- Days 4–5: memorize the 40 CFR 84 GWP limits and dates, the installation definition and labeling.
- Day 6: work through the A2L Refrigerant Safety Practice Test and read every quoted source.
- Day 7: take the timed A2L Refrigerant Safety Full Mock Exam, and retest any group under 80%.
Frequently Asked Questions
What is the A2L refrigerant certification exam?
The best-known option is the HVAC Excellence Low GWP Refrigerant Safety: A2Ls (Mildly Flammable) exam from ESCO Institute. It is a 50-question, closed-book test on flammable refrigerant safety, core ACR knowledge, service, installation, and transport and handling.
How much does the A2L exam cost?
The Virginia CTE Resource Center credential listing for the ESCO exam shows $25 online and $35 on paper.
What score do I need to pass the A2L exam?
The same listing shows a 70% passing score, which means 35 correct out of 50.
Is the A2L exam open book?
No. ESCO describes it as a closed-book exam.
How long is the A2L exam?
The CTE Resource listing shows 120 minutes (minimum) and says extended time is available as needed.
Why are technicians switching to A2L refrigerants?
Under 40 CFR 84.54, new residential and light commercial AC and heat pump systems installed from January 1, 2025 may not use a refrigerant with a GWP of 700 or greater, unless all specified components were made or imported before that date. VRF systems follow from January 1, 2026. Many replacement refrigerants are A2Ls, which is why A2L safety training now matters.
Can I retrofit an existing system to an A2L?
Not under the SNAP listings in 40 CFR Part 82, Subpart G, Appendix X. They allow these A2Ls only in new equipment specifically designed and clearly identified for the refrigerant.
What color are A2L service ports?
Red, PMS #185 or RAL 3020, extending at least 1 inch (25 mm) in both directions from each service port, and replaced if removed.
Can I vent A2L refrigerant?
No. Clean Air Act section 608(c)(2) prohibits knowingly venting substitute refrigerants while servicing or disposing of an appliance, and recovered flammable refrigerants are likely RCRA hazardous waste.
Is there a free A2L practice test?
Yes. Our 155-question practice test quotes the EPA rules behind each answer, and a timed 50-question mock exam follows the ESCO length and 70% pass mark.
TradeExamHub is independent and not affiliated with ESCO Institute, HVAC Excellence or EPA. Our questions quote EPA and eCFR text and do not come from the actual exam.