R-32 Refrigerant and Middle Tennessee Mini-Split Installations: What Changed, What Did Not, and What It Means for Your Decision in 2026

If you have been waiting for clarity on R-32 refrigerant and what it means for your mini-split installation, the single most important update is this: on May 21, 2026, the Environmental Protection Agency issued a final rule that formally removed the January 1, 2026 installation deadline for R-410A residential equipment. The deadline pressure that drove HVAC sales conversations in late 2025 ended on that date. Pre-2025 R-410A equipment that was domestically manufactured or imported before January 1, 2025 remains lawful to install indefinitely. R-32 equipment is the new manufacturing standard for residential mini-splits. The choice between them is now genuine, not deadline-forced.

This article walks through what changed, what did not, and what it means for your decision if you are considering a mini-split installation in Middle Tennessee in 2026. Homeowners are right to ask about a refrigerant described as "mildly flammable." This article addresses that directly, and explains why Tennessee is in a unique legal position on A2L refrigerants compared to most other states.

What changed on May 21, 2026 (and what did not)#

EPA removed the installation deadline but kept the manufacturing cutoff. Pre-2025 R-410A equipment is now indefinitely installable; R-32 is the new manufacturing standard.

On May 21, 2026, EPA published a final rule under the American Innovation and Manufacturing Act of 2020 that removed the January 1, 2026 installation deadline for residential and light commercial air conditioning and heat pump equipment manufactured or imported before January 1, 2025. The EPA fact sheet accompanying the rule states the action "allows for the tens, if not hundreds, of thousands of residential or light commercial AC systems, that were domestically manufactured or imported into the U.S. before January 1, 2025, to continue to be installed."

The January 1, 2025 manufacturing cutoff is unchanged. R-410A residential equipment can no longer be manufactured or imported into the United States. Every major OEM (Daikin, Carrier, Trane, Lennox, Rheem, Goodman, Fujitsu, Mitsubishi) transitioned residential lines to R-32 or R-454B by year-end 2024.

R-410A refrigerant itself remains legal to produce, sell, and use for servicing existing equipment. There is no ban on the refrigerant. The AIM Act phase-down structure continues on its statutory schedule, summarized below.

The AIM Act is a standalone statute passed by Congress and signed by President Trump in December 2020. It is not derived from Clean Air Act greenhouse gas authority, so it is unaffected by other regulatory rollbacks. As HARDI's government affairs office summarized in August 2025: "Through the AIM Act, Congress has directed the agency to phase down HFCs, regardless of the existence of the endangerment finding. Repealing that mandate would require another act of Congress, not an internal EPA rulemaking." The phase-down is on the books.

For a Middle Tennessee homeowner in mid-2026: virgin R-410A residential equipment can no longer be built or imported, but distributor inventory of pre-2025 R-410A equipment can still be installed lawfully. R-32 equipment is the manufacturing default going forward.

What R-32 actually is#

R-32 is a single-component HFC (hydrofluorocarbon) refrigerant that has been the dominant residential mini-split refrigerant globally since 2012. It is mildly flammable but engineered with safety features that make residential installations safe.

R-32 (chemical name difluoromethane, CH2F2) has been used in residential mini-splits in Japan, Europe, and Australia for over a decade. Daikin began shipping R-32 equipment in Japan in November 2012; the global installed base under Daikin's R-32 program reached approximately 58 million units as of March 2025.

GWP and the ASHRAE 34 flammability classification are the two characteristics that matter for the homeowner conversation.

The GWP comparison is the regulatory driver of the transition: EPA's Technology Transitions Rule set a 700 GWP ceiling for new residential AC and heat pump equipment starting January 1, 2025. R-32 meets that ceiling; R-410A does not.

The A2L classification is the safety question worth understanding. "A2L" means lower toxicity (A) with lower flammability and low burning velocity (2L, defined as burning velocity below 10 cm per second, or less than 4 inches per second). For context, R-290 (propane), used in some commercial refrigeration, is classified A3 — materially more flammable than A2L.

The honest description of R-32's flammability: it will not sustain a flame under ambient conditions. It requires very high concentrations combined with an ignition source above 1,198 degrees F to ignite — temperatures that do not occur in normal residential electrical components. UL 60335-2-40 (4th edition) is the equipment standard governing the safety features built into modern A2L equipment, including leak detection, sensor placement, and electrical ignition source suppression.

AHRI's Safe Transition Task Force describes A2L as the second-safest of the eight ASHRAE 34 safety groups. Not "harmless" — the L stands for lower, not zero — but engineered with safety features that make residential installations safe when equipment is properly listed and installed.

Beyond GWP and safety classification, R-32 offers thermodynamic advantages. Daikin's published technical literature reports that R-32 has approximately 10 percent more thermal capacity than R-410A and that systems require approximately 20 to 30 percent less refrigerant mass to achieve the same capacity. Because R-32 is a single-component pure substance, it has zero temperature glide. R-410A is a blend of two gases that leak at different rates, which complicates partial-charge service work; R-32 can be topped off cleanly after a leak repair. Over the 15-year life of a system, that is a real service economics advantage.

Why Tennessee has a unique legal position on A2L refrigerants#

Tennessee enacted a state law in 2022 that specifically authorizes A2L refrigerant use, independent of any International Residential Code adoption cycle. Most Middle Tennessee homeowners — and most HVAC contractors — don't know about this. It matters.

Public Chapter 771 of the Public Acts of 2022 (SB 1801 / HB 1876), signed by Governor Bill Lee on April 8, 2022 and effective the same day, added a new subsection (j) to Tennessee Code Annotated Section 68-120-101. The operative statutory language reads:

A statewide building construction safety standard or another standard or requirement adopted by a local government shall not prohibit, limit, or be enforced to prohibit or limit the use of a refrigerant that is designated as acceptable for use pursuant to and in accordance with 42 U.S.C. Section 7671k, as long as the equipment that contains such refrigerant is listed and installed in accordance with the safety standards and use conditions imposed by federal law or rule for safe alternatives identified pursuant to such designation under 42 U.S.C. Section 7671k.

Plain English: no Tennessee state or local building code can be used to block an A2L install, as long as the equipment is properly listed and installed.

The reference to 42 U.S.C. Section 7671k is Clean Air Act Section 612, the EPA Significant New Alternatives Policy (SNAP) program. R-32 and R-454B are both listed as acceptable substitutes under SNAP for residential AC and heat pump applications. The Tennessee statute therefore preempts any state or local building code that would prohibit A2L installation, provided the equipment is listed (such as to UL 60335-2-40) and installed per the federal use conditions (such as ASHRAE 15.2 charge limits where applicable).

This matters because Tennessee's state-adopted residential code is still IRC 2018, which predates ICC's A2L code language. That language appears in IRC 2021 Chapter M14 and was expanded in IRC 2024. In states without statutory authority like Tennessee's, the IRC adoption lag could be a legitimate barrier to A2L installation. In Tennessee, it is not.

Williamson County's Building Codes Department has adopted the 2021 International Building Code and the 2021 International Residential Code. The 2021 IRC contains the A2L provisions in Chapter M14, so a Williamson County installation has both county-adopted code language and the state statutory authority backing it.

Davidson, Maury, Rutherford, Wilson, Dickson, and most other Middle Tennessee counties operate under State Fire Marshal jurisdiction with the state-adopted IRC 2018, and rely on Public Chapter 771 alone. The state law is sufficient. Local AHJ (Authority Having Jurisdiction, the local building department or inspector) familiarity with A2L equipment does vary across counties, and a credentialed installer should have UL 60335-2-40 listing documentation and Fujitsu installation manuals available at rough-in to forestall any plan-review questions. A2L authorization is one of two recent code requirements that shape Middle Tennessee mini-split work; the other is the September 2026 GFCI requirement for outdoor heat pump and mini-split equipment, which a credentialed installer handles as part of the same plan-review preparation.

ASHRAE 15.2 and your mini-split: why single-zone residential is a non-event#

The trade press has been full of "A2L compliance" coverage focused on charge limits, leak detection systems, and ventilation. For typical single-zone residential mini-splits in Middle Tennessee, none of it applies.

ASHRAE 15.2-2024 sets a charge threshold of 4 pounds. Below this charge level, no mitigation is required. No leak detection system, no minimum room size, no ventilation airflow, no dispersal calculation. The standard treats systems below 4 pounds as safe by design. Above 35 pounds, A2L systems are not acceptable in residential applications. Between 4 and 35 pounds, the installation must comply with charge limit calculations against room dimensions and ventilation.

A typical Fujitsu H-Series single-zone residential mini-split ships with a factory charge well below the 4-pound floor — generally in the 1.5 to 2-pound range for the common 9,000 to 12,000 BTU single-zone configurations Middle Tennessee homeowners install most often. Even with the additional refrigerant required to charge a typical lineset, the total system charge on a single-zone wall-mount installation stays comfortably below the 4-pound floor. No ASHRAE 15.2 mitigation is triggered. (For any specific project, the exact charge values are computed using Fujitsu's Charge Compliance Calculator against the actual outdoor unit, indoor unit, and lineset length specified.)

For a typical Middle Tennessee homeowner installing a single-zone mini-split — a Williamson County bonus room over a garage, a Brentwood finished basement, a sunroom addition, a bedroom retrofit — there is no minimum room size constraint, no leak detection requirement, no required ventilation. The "A2L compliance" worry that dominates the trade press is overwhelmingly a multi-zone and commercial VRF concern, not a residential single-zone concern.

The 4-pound threshold does come into play with larger multi-zone Fujitsu H-Series systems where total charge can run several pounds. For installations approaching or exceeding the threshold, the installer runs a charge-limit calculation against the actual room dimensions and configuration using Fujitsu's Charge Compliance Calculator (Fujitsu's published 3C tool, available through the Airstage contractor portal); ducted H-Series units include factory leak detection as standard equipment.

The Fujitsu H-Series R-32 lineup: warranty and performance#

The Fujitsu H-Series R-32 lineup carries strong warranty terms, with extensions tied to specific installation conditions. The performance numbers cover Middle Tennessee winters at full rated capacity, with no supplemental heat required.

The entire AIRSTAGE H-Series residential mini-split line is now R-32. The R-410A H-Series lineup that preceded it rolled off Fujitsu manufacturing per the January 1, 2025 AIM Act cutoff.

Per Fujitsu's published R-32 Limited Warranty (Version 20241020), the standard terms are 5 years on parts and 7 years on the compressor. Fujitsu extends those terms to 10 years on both parts and compressor when all of the following conditions are met: the system is registered online within 60 days of installation, the system is installed in a residential single-family or owner-occupied multifamily home, the purchaser resides at the installation location, and the system was purchased after January 1, 2025. Fujitsu further extends the term to 12 years on parts and compressor when the system is installed by a Fujitsu Elite Contractor (an independent contractor designation Fujitsu administers, separate from the general installer base). Section 5(r) of the warranty explicitly excludes any R-410A or R-22 systems, confirming the enhanced R-32 terms apply only to R-32 equipment. Section 5(b) excludes systems purchased from online retailers, which has implications for DIY kit purchases discussed below.

A 10-year or 12-year parts-and-compressor warranty on properly installed R-32 equipment means the homeowner is largely insulated from major component replacement costs over the first decade-plus of system life. Pre-2025 R-410A H-Series equipment, even when installed lawfully under the May 2026 EPA rule, does not qualify for these extended terms.

The performance numbers, from Fujitsu's published H-Series R-32 announcement:

For Middle Tennessee specifically, this matters because Nashville's Manual J design temperature is 13 degrees F (Climate Zone 4A). The H-Series R-32 equipment delivers full rated heating capacity well below the design temperature, with substantial reserve. No supplemental heat requirement, no auxiliary strip heat, no concern about cold-snap performance.

A note on the SEER2 number specifically: equipment design (compressor modulation, coil sizing, expansion device, blower motor, control firmware) matters more than the refrigerant choice. R-32 contributes thermodynamic advantages, but a well-designed system architecture matters more than the molecule. The 33.5 SEER2 ceiling reflects equipment redesign opportunities Fujitsu took when transitioning, not R-32 by itself.

R-410A in 2026: still legal, but the service economics are changing#

Pre-2025 R-410A equipment is lawful to install in Tennessee under the May 2026 EPA rule. But the long-run service economics get materially worse starting around 2029, when the AIM Act phase-down steps down to 70 percent reduction.

R-410A refrigerant production is being phased down on the schedule shown in the table above. Service refrigerant remains legal indefinitely, but the supply structure shifts toward reclaimed material as virgin allowances tighten. A-Gas, an EPA-certified refrigerant reclaimer, summarizes the trajectory: "The phase-down of available virgin gases will greatly outpace the demand for both new equipment and the ongoing servicing of existing equipment. This gap will be filled by reclaimed gases." A-Gas has a commercial interest in the reclamation narrative, but the trajectory it describes matches EPA's own AIM Act program reports and AHRI industry guidance.

R-410A wholesale pricing reflects the phase-down already. As of early 2026, AC Direct's published tracking puts 25-pound R-410A cylinders at $430 to $470 (roughly $18 to $20 per pound at wholesale). Homeowner-installed recharge pricing runs $40 to $75 per pound, with some markets and emergency calls reaching $90 per pound. AC Direct attributes the trajectory to AIM Act mechanics, with prices up roughly 40 to 70 percent from the 2022 baseline due to EPA-mandated production cap step-downs. ACHR News refrigerant pricing coverage across 2025-2026 has tracked similar trajectories.

The honest 15-year cost comparison for a homeowner installing today: a 2026 R-410A install is legal and the equipment will function for its design life. Service refrigerant will be available throughout that life. The 2029 step-down to 70 percent reduction is the realistic inflection point — a homeowner installing R-410A in 2026 should price in materially higher recharge costs starting around 2029-2030. The system is not stranded; it just gets more expensive to service over time.

Equipment pricing has roughly approached parity in early 2026 between R-32 systems and remaining R-410A inventory, with clearance pricing on pre-2025 R-410A overstock where it exists. R-32 refrigerant pricing has normalized after early-transition shortages, and as a single-component product, its long-run reclamation economics are more favorable than the R-410A blend. Combined with the 10-year (or 12-year, with Elite Contractor installation) Fujitsu warranty available on R-32 H-Series equipment, R-32 is the clear pick for a new install in mid-2026.

R-32 vs R-454B: why this is not a "pick the winning refrigerant" question#

Both R-32 and R-454B will coexist for the residential life of any system installed in 2026, because they have settled into different applications. Mini-splits are an R-32 market. Central ducted is largely an R-454B market.

Homeowners doing their own research encounter both R-32 and R-454B as 2025-and-later refrigerants and reasonably ask which one will win.

Mini-splits as a category went almost entirely to R-32. Daikin (the global leader), Fujitsu, Mitsubishi-branded equipment, and LG all use R-32 for their residential mini-split lines. Central ducted is largely an R-454B market: Carrier, Trane, Lennox, Rheem, Goodman, and Bosch use R-454B (also known as Solstice or Opteon XL41) for their residential central air conditioning and heat pump lines.

Both meet the 700 GWP ceiling. R-454B's GWP advantage (466 vs R-32's 675) matters at the manufacturer level for AIM Act allowance accounting but does not translate into a homeowner-facing decision factor. No tightening of the GWP ceiling below 500 is in EPA's pipeline as of May 2026. The May 2026 final rule loosened rather than tightened the schedule.

If you are installing a mini-split, R-32 is the refrigerant. If you are installing central ducted, R-454B is the refrigerant. The "pick the winning refrigerant" framing is the wrong question.

What about DIY mini-split kits?#

Pre-charged DIY mini-split kits do not exempt the installer from EPA Section 608 certification. The certification requirement applies to all refrigerant handling, regardless of refrigerant class. And the Fujitsu warranty specifically excludes systems purchased from online retailers.

The DIY mini-split market has expanded materially in 2024-2026 (MRCOOL, Pioneer, and others), and the EPA Section 608 question comes up regularly.

Per 40 CFR Part 82 Subpart F under Section 608 of the Clean Air Act, certification is required for anyone who "maintains, services, repairs, or disposes of equipment that could release refrigerants into the atmosphere." EPA's published guidance specifically includes attaching and detaching hoses and gauges, and adding or removing refrigerant. Pre-charged quick-connect linesets in DIY kits do not change this. If a connection fails or refrigerant must be added, recovered, or topped off, EPA 608 certification is required regardless of refrigerant class.

A2L refrigerants carry an additional practical restriction: 25-pound cylinders cannot be purchased without 608 credentials. A homeowner who installs a DIY kit and later needs service is on the hook for finding a certified technician, often with the added complication of warranty issues.

Fujitsu's R-32 Limited Warranty Section 5(b) excludes "Any System purchased from an online retailer." For homeowners considering DIY routes that source Fujitsu equipment online, this exclusion is worth understanding before purchase — the warranty terms discussed earlier (10-year and 12-year extensions) require that the system be purchased through Fujitsu's authorized contractor channels. Online-purchased Fujitsu equipment falls outside the warranty entirely, regardless of installation quality.

There is no separate "608 A2L endorsement," though training organizations including RSES, ESCO, NATE, AHRI, and ACCA offer A2L-specific competency training that is increasingly expected by employers and insurers.

What this means for your decision in 2026#

For a new mini-split installation in mid-2026, R-32 H-Series equipment is the right call on warranty, service economics, and performance grounds. The deadline pressure that drove late-2025 sales tactics is gone. The decision should be made on lifecycle economics, not regulatory cliff.

The May 21, 2026 EPA final rule changed the conversation. Pre-2025 R-410A inventory is now indefinitely installable in Tennessee, so the choice between R-32 and R-410A is genuine rather than deadline-forced.

The honest case for R-32 H-Series equipment rests on three things working together. The warranty advantage is real: 10 years on parts and compressor for properly registered installations, or 12 years with Fujitsu Elite Contractor installation, against zero extended-warranty eligibility on pre-2025 R-410A inventory. The service economics favor R-32 over the 15-year life of the system, with R-410A recharge costs climbing steadily through the AIM Act phase-down and the 2029 step-down accelerating the trajectory. The performance ceiling on R-32 H-Series equipment (33.5 SEER2, full rated heating capacity to -15 degrees F) covers Middle Tennessee climate conditions comfortably. Up-front cost belongs in the same lifecycle picture: the TVA rebates and other 2026 incentives apply to qualifying high-efficiency R-32 equipment and can offset a meaningful share of the install cost.

The case for pre-2025 R-410A inventory is narrower but real, where genuine clearance pricing exists, where matching equipment elsewhere on the property makes practical sense, or where the equipment selection is driven by something other than the refrigerant.

For Middle Tennessee homeowners specifically, the legal path is clear under Tennessee Public Chapter 771 of 2022. The state authorizes A2L installation independently of code adoption cycles. ASHRAE 15.2 charge limits do not constrain typical single-zone residential installations. The infrastructure for clean, code-compliant R-32 installation is in place.

The transition has happened. The question is no longer whether to transition, but whether to install now (with warranty and service economics favoring R-32) or to defer for reasons unrelated to refrigerant choice. There is no foreseeable next-generation refrigerant coming that justifies waiting.

Frequently asked questions#

Is R-32 dangerous in my home?#

R-32 is classified A2L by ASHRAE Standard 34: lower toxicity and lower flammability with low burning velocity. It will not sustain a flame under ambient conditions and requires very high concentrations combined with an ignition source above 1,198 degrees F to ignite — temperatures that do not occur in normal residential electrical components. Modern R-32 equipment is built to UL 60335-2-40 (4th edition) with engineered safety features. For typical single-zone residential mini-split installations, the factory charge sits below the 4-pound ASHRAE 15.2 threshold that triggers any additional mitigation requirements.

Can I still get R-410A equipment installed in Tennessee?#

Yes, if the equipment was manufactured or imported into the United States before January 1, 2025. The EPA final rule of May 21, 2026 formally removed the January 1, 2026 installation deadline for pre-2025 R-410A residential equipment. Distributor inventory of pre-2025 R-410A H-Series equipment can be lawfully installed in Tennessee. Virgin R-410A equipment can no longer be manufactured or imported.

Will R-410A refrigerant be available to service my system in 10 to 15 years?#

Yes, but at increasingly higher prices. R-410A refrigerant remains legal to produce, sell, and use for servicing existing equipment indefinitely. The AIM Act phase-down reduces production allowances on a statutory schedule (70 percent reduction in 2029, 80 percent in 2034, 85 percent in 2036). Reclaimed R-410A is scaling to fill the gap. A homeowner installing R-410A equipment in 2026 should expect materially higher service refrigerant costs starting around 2029-2030, with reclaimed material becoming the practical default.

Do I need a special inspector or permit for an R-32 mini-split install?#

In Tennessee, no. Public Chapter 771 of 2022 authorizes A2L refrigerant use directly, independent of code adoption. Williamson County's adopted 2021 IRC contains A2L provisions in Chapter M14. The standard permitting process applies. Local inspector familiarity with A2L equipment varies, and a properly credentialed installer should have UL 60335-2-40 listing documentation and Fujitsu installation manuals available at rough-in.

Is R-32 going to be replaced soon by a newer refrigerant?#

Not in any foreseeable horizon. R-32 has been the dominant residential mini-split refrigerant globally since 2012. No regulatory action is in EPA's pipeline that would tighten the GWP ceiling below R-32's 675 value, and the May 2026 final rule moved in the opposite direction. Both R-32 and R-454B will remain the residential standards for the next decade-plus.

Why does my neighbor's central air conditioner use R-454B instead of R-32?#

Different equipment platforms settled on different refrigerants. Mini-splits as a category went almost entirely to R-32 (Daikin, Fujitsu, Mitsubishi-branded, LG). Central ducted equipment went largely to R-454B (Carrier, Trane, Lennox, Rheem, Goodman). Both meet the EPA 700 GWP ceiling. The split reflects manufacturer engineering decisions, not a quality or safety difference homeowners need to weigh.

Does my installer need special certification to work on R-32?#

The legal requirement is EPA Section 608 Certification, which applies to all refrigerant work regardless of refrigerant class. There is no separate "608 A2L endorsement." Training organizations including RSES, ESCO, NATE, AHRI, and ACCA offer A2L-specific competency training that is increasingly expected by employers and insurers but is not a separate legal certification.

What about DIY mini-split kits with pre-charged linesets?#

EPA Section 608 certification is required to install, service, or recover refrigerant from any HVAC equipment, including DIY mini-split kits with pre-charged linesets. The pre-charge does not exempt the installer from the certification requirement. If a connection fails or refrigerant must be added or recovered, certification is required by federal law. A2L refrigerant cylinders also cannot be purchased without 608 credentials. Additionally, Fujitsu's R-32 warranty (Section 5(b)) excludes systems purchased from online retailers, so Fujitsu equipment sourced through DIY channels would not carry the manufacturer warranty.

Sources and references#

EPA AIM Act and Technology Transitions Rule#

• EPA, "Final Rule: Technology Transitions Program under Subsection (i) of the American Innovation and Manufacturing Act of 2020," published May 21, 2026.
• EPA Technology Transitions Rule fact sheet (May 2026), epa.gov/system/files/documents/2026-05/fact-sheet-san-12166-technology-transitions-frm.pdf.
• EPA, "Phasedown of Hydrofluorocarbons."
• EPA Section 608 Technician Certification Requirements.

Tennessee state law#

• Public Chapter 771 of the Public Acts of 2022 (SB 1801 / HB 1876), effective April 8, 2022.
• T.C.A. Section 68-120-101(j), codified text.
• CTAS (University of Tennessee County Technical Assistance Service) 2022 Index of Acts.
• Williamson County Building Codes Department, Adopted Codes.

ASHRAE standards#

• ASHRAE Standard 34, Designation and Safety Classification of Refrigerants.
• ASHRAE Standard 15-2022, Safety Standard for Refrigeration Systems.
• ASHRAE Standard 15.2-2024, Safety Standard for Refrigeration Systems in Residential Applications.

Manufacturer documentation#

• Fujitsu General, "Next Generation Refrigerants: R-32" homeowner education page.
• Fujitsu AIRSTAGE H-Series R-32 Announcement.
• Fujitsu R-32 Limited Warranty (Version 20241020).
• Fujitsu Application Bulletin R20250324C (April 2026), R-32 charge limit tables.
• Fujitsu Charge Compliance Calculator (3C tool), Airstage contractor portal.
• Daikin Comfort, "R-32 Refrigerant Technology."
• Daikin Global CSR Information on R-32 (March 2025 figures).
• Honeywell Refrigerants, Genetron 32 product data sheet.

Industry analysis#

• AHRI A2L Refrigerant Building Code Map.
• HARDI Government Affairs, "EPA Rollback Does Not Affect HFC Phasedown," August 2025.
• ACHR News coverage of EPA Technology Transitions Rule changes and refrigerant pricing trajectories (2025-2026).
• ACCA HVAC Blog coverage of EPA enforcement and rulemaking.
• A-Gas, "AIM Act and the Refrigerant Transition."
• AC Direct, R-410A cost and availability tracking (early 2026 figures).
• Contracting Business, "ASHRAE Standard 15 Guidance for A2L Refrigerants."

Tennessee code#

• Tennessee Mechanical Code 2021 (IMC 2021) Chapter 11, Refrigeration.
• Tennessee state-adopted codes (IRC 2018 residential, NEC 2017, IMC 2021 commercial).