Cooling # R-410A vs R-454B: which should a new system use? New residential systems use R-454B because R-410A, at a GWP of 2,088, exceeds the 700 limit applying to equipment manufactured from January 1, 2025. R-410A systems built before that date can still be legally installed from remaining stock — EPA removed the installation deadline on May 21, 2026. **Jurisdiction notice. **Efficiency standards, refrigerant rules, incentives, and licensing are set federally, by region, and by state, and they change. This page reflects EPA rules under the AIM Act as of 2026-08-17. Verify before purchasing. ## The criteria being compared Both cool a house the same way. What separates them is regulatory status, global warming potential, flammability classification, and what each means for servicing over the system's life. CriterionR-410AR-454B GWP (EPA exchange value) 2088465Under the 700 limit? NoYesSafety classification A1 (non-flammable)A2L (mildly flammable)In newly built equipment? No, since 2025-01-01YesCan still be installed? Yes — pre-2025 stock, no deadlineYesServicing existing systems Legal, refrigerant availableLegal; needs A2L-trained technicians ## The verdict **For a new system, you will almost certainly be offered R-454B or R-32, and that is fine.** A2L means mildly flammable, which changes service procedures and leak detection — it does not make the equipment unsafe to own or operate. **Being offered pre-2025 R-410A stock is not automatically a red flag,** and it is legal. But ask two questions: what will refrigerant and parts availability look like over the next fifteen years, and is the price discounted to reflect that? If the answer to the second is no, the discount is going to the seller, not to you. Either way, ask whether the technicians are trained on A2L refrigerants. Shops that were not servicing A2L five years ago have had to retrain. ## How do you recognise a good contractor? Not by the brand they sell, and not by how long they have been in business. You recognise them by what they measure before quoting, and by what they are willing to put in writing. ## What should a bid show you? Three bids rarely quote the same job, so comparing headline price compares three different things. The one that was done properly shows its work, and you can check it line by line: - Model numbers for the outdoor unit, indoor coil, and air handler or furnace. - The **AHRI reference number** for that exact combination. A rating applies to a matched system, not to an outdoor unit on its own. - The SEER2 and, on a heat pump, the HSPF2 of that combination. - The Manual J result the sizing came from. - The measured static pressure and any duct work included. - The permit, and who pulls it. - Labour warranty, separate from parts, and whether registration is required. [The full red-flags checklist](https://hvacbuddy.shop/hiring/). ## How is the right equipment size decided? Nearly every persistent comfort problem traces back to equipment size, and size is decided before the first box arrives. The standard is the ACCA **Manual J** load calculation (ANSI/ACCA 2 Manual J - 2016), which totals the heat gain and loss of your specific house: orientation, window area and type, insulation levels, air infiltration, internal gains, and your local design temperature. What a Manual J is *not*: square feet per ton, and not the old unit's tonnage. The first ignores everything that makes one house different from another. The second assumes whoever sized the old equipment got it right, and propagates their error for another fifteen years. Oversized equipment reaches the setpoint and shuts off before it has dehumidified, so the house ends up cold and clammy at the same time. Every start is also the hardest moment in a compressor's life, so wear accelerates. And you pay for the surplus capacity twice — once to buy it and again to run it. Ask for the completed Manual J in writing, not the claim that one was done. [What it contains and how to read it](https://hvacbuddy.shop/sizing/manual-j/). ## Why do the ducts matter as much as the equipment? Equipment capacity is rated at a specific airflow. If the ducts cannot move that air, the equipment cannot deliver what its label promises, and the homeowner concludes they were oversold. The number that reveals it is **static pressure**: the resistance the blower works against, measured in inches of water column. It is to a duct system roughly what blood pressure is to a person. A contractor who measures it before quoting a replacement is doing the job; one who does not is assuming your ducts are fine. Duct design has its own ACCA standard, **Manual D**, and it is the step most often skipped on a replacement because the ducts already exist and reusing them costs nothing up front. [What Manual D determines](https://hvacbuddy.shop/ductwork/manual-d/) · [ducts and airflow](https://hvacbuddy.shop/ductwork/). ## What actually drives the cost? We publish no national average price, and the reason matters: an average across every house, region and system type is not a number you can act on. A replacement that includes duct modification, an electrical upgrade and a permit is a different job from a straight swap, and both read as "system replacement" on a one-page proposal. What actually drives your number: - **Equipment capacity and tier**, which should come from the Manual J rather than the old nameplate. - **The ducts** — whether they can move the air the new equipment needs, and what it costs if they cannot. - **Electrical work**, if a circuit or panel change is required. - **Permit and inspection**, usually required. - **Refrigerant** — current equipment uses R-454B or R-32; remaining pre-2025 R-410A stock may price differently. [What a bid should itemise](https://hvacbuddy.shop/costs/) · [operating cost calculator](https://hvacbuddy.shop/calculators/). ## How can you verify any of this yourself? Everything regulatory on this site traces to a primary source and carries the date it was read: DOE for efficiency standards, EPA for refrigerants and Section 608, the IRS for tax credits, and ACCA for load calculation. The sources for this page are listed at the end with the date each was consulted. If you find a different figure elsewhere, check two things before deciding which to believe: whether the page says which generation its efficiency metric belongs to, and whether it carries a visible review date. Most of the outdated content in this category fails both tests. Sources (2) - U.S. Environmental Protection Agency — [Technology Transitions GWP Reference Table](https://www.epa.gov/hfcs/technology-transitions-gwp-reference-table) (accessed 2026-08-17) - U.S. Environmental Protection Agency — [Technology Transitions HFC Restrictions by Sector](https://www.epa.gov/climate-hfcs-reduction/technology-transitions-hfc-restrictions-sector) (accessed 2026-08-17) By [HVACBuddy Editorial Team](https://hvacbuddy.shop/authors/editorial-team/). Last reviewed: 2026-08-18. Verified: 2026-08-17 HVACBuddy publishes independent information. We do not install or service equipment, we do not dispatch contractors, and we do not sell leads. Nothing here is engineering, tax, or legal advice.