Original data and independent reporting for the HVAC trade

Author: The HVAC Brief Editorial Team

  • Can You Still Get R-22? What Ended and What Did Not

    Can You Still Get R-22? What Ended and What Did Not

    Last reviewed: August 2026 · By the HVAC Brief Editorial Team · Our sourcing and editorial standards

    The short answer

    R-22 has not been produced or imported in the United States since January 1, 2020, under the Clean Air Act ozone-depleting substance phaseout. What remains available is recovered and reclaimed material from existing systems.

    Servicing an R-22 system is still legal. The supply is finite and no longer replenished by production, which is a different constraint from the HFC phasedown now affecting R-410A.

    Two separate regulatory schemes are involved and they get conflated constantly. R-22 was phased out because it depletes ozone, under Title VI of the Clean Air Act. R-410A is being phased down because of its global warming potential, under the AIM Act. Different laws, different mechanisms, different timelines.

    The two phaseouts compared

    R-22 R-410A
    Reason Ozone depletion Global warming potential
    Authority Clean Air Act Title VI AIM Act, 40 CFR part 84
    Mechanism Production and import ended Declining production allowances
    Status No new production since January 1, 2020 Capped and stepping down, next step 2029
    Servicing existing systems Legal, using reclaimed material Legal
    New residential equipment Long since unavailable Barred since January 1, 2025

    The practical difference matters. R-22 supply cannot grow, because nothing new is made. R-410A supply is being reduced on a schedule but still produced. See our phasedown schedule.

    What this means for an R-22 system

    1. It remains legal to operate and service. No rule requires replacing a working R-22 system.
    2. Refrigerant comes from reclamation. Recovered from decommissioned systems, cleaned to specification, and resold.
    3. A leak is a bigger decision than it used to be. Any repair opening the circuit means recharging from a finite supply.
    4. Retrofit refrigerants exist but change system behaviour and are not a drop-in equivalent in the way marketing sometimes implies.
    5. Age is the real signal. A system still on R-22 has been in service a long time, which bears on repair-versus-replace independently of refrigerant.
    The question to ask about a repair quote

    If a technician proposes recharging an R-22 system, ask whether the leak has been located and what the plan is if it recurs. Repeatedly recharging from a finite, unreplenished supply is the least defensible version of this decision, both economically and environmentally. See how to sanity check a repair quote.

    Frequently asked questions

    Can you still get R-22 refrigerant?

    Yes, but only recovered and reclaimed material. Production and import into the United States ended on January 1, 2020 under the Clean Air Act ozone-depleting substance phaseout, so the supply is finite and no longer replenished. Servicing existing R-22 systems remains legal.

    Is it illegal to run an R-22 air conditioner?

    No. No rule requires replacing a working R-22 system, and servicing one is legal using reclaimed refrigerant. What ended was production and import of the substance, not the operation or maintenance of equipment containing it.

    What is the difference between the R-22 and R-410A phaseouts?

    Different laws and mechanisms. R-22 was phased out for ozone depletion under Clean Air Act Title VI, with production and import ending January 1, 2020. R-410A is being phased down for its global warming potential under the AIM Act, through declining production allowances rather than an end date.

    Should I replace an R-22 system?

    The refrigerant is one input to that decision rather than the whole of it. A system still on R-22 has been in service a long time, and any repair opening the refrigerant circuit means recharging from a finite supply. Weigh the specific repair against replacement rather than treating the refrigerant alone as decisive.

    Methodology and limitations

    The R-22 production and import phaseout under Clean Air Act Title VI, effective January 1, 2020, is the established regulatory position. The R-410A phasedown figures are from 40 CFR 84.7 and the residential equipment restriction from 40 CFR 84.54.

    • We publish no refrigerant prices. No federal series tracks residential refrigerant pricing.
    • Retrofit refrigerant options are named as a category only. Suitability is equipment specific.
    • Nothing here is legal or engineering advice for a specific system.

    Sources

    1. US Environmental Protection Agency, Clean Air Act Title VI ozone-depleting substance phaseout, 40 CFR part 82 subpart A.
    2. US Environmental Protection Agency, 40 CFR 84.7, HFC phasedown schedule, and 40 CFR 84.54.

    The HVAC Brief is an independent trade publication. We do not sell equipment, take manufacturer advertising, or accept payment for placement in our research. Corrections welcome.

  • MERV Ratings: Why the Highest Filter Is Not the Best Filter

    MERV Ratings: Why the Highest Filter Is Not the Best Filter

    Last reviewed: August 2026 · By the HVAC Brief Editorial Team · Our sourcing and editorial standards

    The short answer

    A higher MERV filter captures more particles and also restricts more airflow, and residential systems are not all designed for the denser end of the scale. Fitting the highest available rating is not automatically an upgrade.

    MERV, Minimum Efficiency Reporting Value, rates how effectively a filter captures particles across defined size ranges. It says nothing about whether your blower can move air through it at the rate the system needs.

    The trade-off is real and mechanical. Filtration and airflow pull against each other, and the correct choice depends on the system, the ductwork and the filter area available, not on picking the largest number.

    What MERV measures

    The rating describes capture efficiency across particle size ranges, with higher numbers capturing smaller particles more effectively. It is a laboratory measure of the filter medium, tested to a standard published by a private standards body, and it is not a measure of installed system performance.

    What rises with MERV What also rises
    Capture of smaller particles Pressure drop across the filter
    Capture efficiency overall Static pressure across the blower
    Perceived air quality benefit Blower energy use, and motor load
    Filter cost Rate at which restriction worsens as it loads

    Why filter area matters more than rating

    1. Pressure drop falls as filter area rises. A physically larger or deeper filter of the same rating restricts less than a thin one.
    2. A four or five inch media cabinet gives far more surface area than a one inch slot, which is why higher ratings are viable there.
    3. A one inch filter at a high rating is where problems concentrate, because the area is small and the restriction is high.
    4. Restriction worsens as the filter loads, so a filter that was acceptable when clean may not be near the end of its interval.
    The measurement that settles it

    Static pressure across the air handler tells you whether the system is working against more resistance than it was designed for. It is the only way to know whether a given filter is appropriate for a specific system, and it is worth asking for if comfort or airflow problems appeared after a filter change. See why static pressure matters.

    Filters do not ventilate

    A filter cleans air already inside the house as it recirculates. It does not exchange indoor air with outdoor air. If the concern is fresh air rather than particles, the filter is the wrong lever entirely. See what ventilation actually means.

    Frequently asked questions

    What MERV rating should I use?

    It depends on the system and the filter housing rather than on a universal recommendation. Higher ratings restrict more airflow, and a one inch filter slot has far less area than a four or five inch media cabinet, so the same rating behaves very differently in each. Static pressure measurement is what establishes whether a given filter suits a specific system.

    Is a higher MERV filter always better?

    No. Higher ratings capture more particles and also increase pressure drop across the blower, reducing airflow and loading the motor. Whether that trade is acceptable depends on the system design, ductwork and available filter area. Fitting the highest rating available is not automatically an improvement.

    Can a filter damage my HVAC system?

    A filter that is too restrictive for the system raises static pressure, which reduces airflow, degrades capacity and dehumidification, and loads the blower motor. Sustained high static pressure is associated with blower motor stress. The filter itself does not fail the system, the resistance it creates does.

    Will a better filter improve indoor air quality?

    It improves filtration of the air already circulating, which addresses particles. It does not bring in outdoor air, so it does nothing for anything requiring air exchange. It also increases resistance across the blower, so the benefit is not free.

    Methodology and limitations

    MERV is defined by a private standard which we name but do not reproduce. This page describes the mechanical trade-off between filtration and airflow rather than recommending a rating, because the appropriate choice depends on system design and filter housing.

    • No MERV rating is recommended here. The right choice is system specific.
    • No pressure drop figures are published, as they depend on filter construction, area and loading.
    • Nothing here is engineering advice for a specific installation.

    The HVAC Brief is an independent trade publication. We do not sell equipment, take manufacturer advertising, or accept payment for placement in our research. Corrections welcome.

  • Why a Furnace Will Not Ignite: The Sequence and Where It Stops

    Why a Furnace Will Not Ignite: The Sequence and Where It Stops

    Last reviewed: August 2026 · By the HVAC Brief Editorial Team · Our sourcing and editorial standards

    The short answer

    A modern gas furnace will not ignite unless every safety interlock in its start sequence proves out. Most no-heat calls are the furnace correctly refusing to run, not the furnace failing.

    The sequence is: thermostat calls, inducer proves draught through a pressure switch, igniter heats, gas valve opens, flame sensor confirms flame, blower starts. A failure at any step stops ignition, and the control board usually flashes a code identifying which.

    Knowing the sequence tells you which failures are homeowner-checkable and which are not. It also explains the most common pattern: a furnace that lights, runs briefly, then shuts down and retries.

    The ignition sequence

    1. Thermostat calls for heat. A circuit closes and the control board wakes.
    2. Inducer motor starts and establishes draught through the heat exchanger and flue.
    3. Pressure switch proves draught. If it does not close, the sequence stops here and nothing lights.
    4. Igniter energises, either a hot surface igniter or a spark.
    5. Gas valve opens and the burners light.
    6. Flame sensor confirms flame within a few seconds. If it does not, the gas valve closes.
    7. Blower starts after a delay so it does not push cold air.

    What each failure looks like

    Symptom Likely stage Homeowner checkable
    Nothing happens at all Power, thermostat, door switch Yes, partly
    Inducer runs, nothing lights Pressure switch or blocked flue Check flue terminal for blockage
    Lights, runs a few seconds, shuts off, retries Flame sensor No
    Igniter glows but no flame Gas supply or gas valve Check gas is on elsewhere
    Runs then overheats and cuts out Airflow, filter or ductwork Yes, filter first
    Repeated lockout after several tries Control board has locked out deliberately No
    The classic: lights then quits after five seconds

    That pattern almost always points at flame sensing. The furnace lights, fails to confirm the flame, and closes the gas valve as designed. It is a safety system working correctly on bad information, and it recurs until the sensing issue is addressed. It is not a homeowner repair.

    What to check before calling

    The filter, because restricted airflow causes overheat cutouts and is the most common owner-fixable cause. The thermostat mode and batteries. The furnace door switch, since many furnaces will not run with the panel off. Whether other gas appliances work, which separates a furnace fault from a gas supply problem. And the outdoor flue terminal, which can block with snow or debris on sidewall-vented equipment.

    Beyond that, the diagnostic requires measurement. Anything involving the gas valve, flame sensing or the heat exchanger is a service call.

    Frequently asked questions

    Why does my furnace light then shut off?

    Most often flame sensing. The furnace lights, fails to confirm flame within a few seconds, and closes the gas valve as a safety response, then retries. It is the safety system working correctly on bad information. After several failed attempts the control board locks out deliberately.

    Why is my furnace not igniting at all?

    If the inducer runs but nothing lights, the sequence has usually stopped at the pressure switch, which proves draught before gas is allowed to flow. A blocked flue terminal, particularly on sidewall-vented equipment in snow, prevents that switch closing. If nothing happens at all, check power, thermostat and the furnace door switch.

    Can I fix a furnace that will not ignite?

    The owner-checkable items are the filter, thermostat mode and batteries, the furnace door switch, whether other gas appliances work, and whether the outdoor flue terminal is blocked. Anything involving the gas valve, flame sensing or the heat exchanger requires a qualified technician.

    What does a furnace lockout mean?

    The control board has stopped attempting ignition after repeated failures, deliberately, to avoid releasing unburned gas. Resetting power clears it, but if the underlying fault persists the furnace will lock out again. Repeated resets without diagnosis are not a fix.

    Methodology and limitations

    This page describes the standard sequence of operation for modern induced-draught gas furnaces. Sequences vary between manufacturers and models, and the manufacturer’s literature is authoritative for any specific unit.

    • No failure frequencies are claimed. No federal source measures residential furnace fault rates.
    • Gas appliance work carries safety risk and is not owner serviceable beyond the checks listed.
    • Diagnostic codes vary by manufacturer. Read the code chart on the unit rather than assuming a meaning.

    The HVAC Brief is an independent trade publication. We do not sell equipment, take manufacturer advertising, or accept payment for placement in our research. Corrections welcome.

  • Why Your House Is Cold but Humid (and Why a Bigger AC Makes It Worse)

    Why Your House Is Cold but Humid (and Why a Bigger AC Makes It Worse)

    Last reviewed: August 2026 · By the HVAC Brief Editorial Team · Our sourcing and editorial standards

    The short answer

    Air conditioning removes humidity only while the coil is running, so a system that cools the house quickly and shuts off leaves it cool and clammy. That is the classic signature of an oversized system.

    Dehumidification is a function of run time, not of capacity. Adding capacity to a humidity problem usually makes it worse, because the system reaches setpoint faster and runs less.

    This is the most consequential misunderstanding in residential cooling, because the intuitive fix is exactly wrong. Understanding the mechanism tells you whether the answer is equipment, sizing, airflow or a dedicated dehumidifier.

    How an air conditioner removes moisture

    1. Warm humid air passes over the evaporator coil, which is below the dew point of that air.
    2. Water vapour condenses onto the cold coil surface.
    3. Condensate drains into a pan and out through the condensate line.
    4. The air leaving the coil is both cooler and drier.

    Every step depends on the coil being cold and air moving across it. Stop the compressor and moisture removal stops immediately, while the water already on the coil begins re-evaporating into the airstream.

    Why oversizing causes clamminess

    System behaviour Temperature Humidity
    Correctly sized, longer run cycles Reaches setpoint steadily Removed throughout the cycle
    Oversized, short cycles Reaches setpoint quickly Little removed before shutdown
    Restricted airflow Poor cooling Coil may freeze, then flood on thaw

    An oversized system satisfies the thermostat before it has done much dehumidification, then stops. The house is at temperature and still humid, which reads as cold and clammy rather than comfortable. Our sizing guide covers why square-foot rules produce this.

    Why lowering the thermostat does not fix it

    Dropping the setpoint makes the system run longer, which does remove more moisture, but it does so by overcooling the house. You are treating a humidity problem with temperature, which is why the room ends up cold and still uncomfortable. See what a thermostat can and cannot do.

    Frequently asked questions

    Why is my house cold but humid?

    Usually an oversized system short cycling. Air conditioning removes moisture only while the coil runs, so a system that reaches setpoint quickly and shuts off cools the air without dehumidifying it. Adding capacity makes this worse rather than better, because the system then runs even less.

    Does air conditioning dehumidify?

    Yes, as a by-product of cooling. Warm humid air passing over a coil below its dew point condenses water onto the coil, which drains away. The effect depends entirely on run time: moisture removal stops the moment the compressor stops, and water already on the coil begins re-evaporating.

    Will a bigger air conditioner fix humidity?

    No, it typically worsens it. Larger capacity reaches the thermostat setpoint faster, which shortens run cycles and reduces the time the coil is available to condense moisture. Correct sizing, adequate airflow or a dedicated dehumidifier address humidity; extra capacity does not.

    Should I lower the thermostat to reduce humidity?

    It extends run time and so removes more moisture, but at the cost of overcooling the house. That treats a humidity problem with temperature and usually leaves the room cold and still uncomfortable. The underlying issue is normally sizing or airflow.

    Methodology and limitations

    This page describes the physical mechanism of coil dehumidification and the consequences of run-time behaviour. We publish no humidity targets or capacity figures, as appropriate values depend on climate, building and occupancy.

    • No target relative humidity is recommended here.
    • Variable capacity equipment modulates output and behaves differently from the single stage case described.
    • Nothing here is engineering advice for a specific system.

    Sources

    1. US Department of Energy, 10 CFR 430.32, for equipment staging and rating context.

    The HVAC Brief is an independent trade publication. We do not sell equipment, take manufacturer advertising, or accept payment for placement in our research. Corrections welcome.

  • Why Single-Hose Portable Air Conditioners Underperform

    Why Single-Hose Portable Air Conditioners Underperform

    Last reviewed: August 2026 · By the HVAC Brief Editorial Team · Our sourcing and editorial standards

    The short answer

    A single-hose portable air conditioner exhausts indoor air outside, which pulls unconditioned outdoor air into the room through every gap to replace it. That is a physical consequence of the design, not a defect.

    It is why a portable unit rated the same as a window unit performs worse in the same room. The rating measures the machine; the hose configuration determines how much of that output reaches you.

    Portable units solve a real problem: rooms where a window unit cannot be fitted, rented properties, and windows that do not take a standard sash mount. Understanding the trade-off lets you choose well rather than expecting window-unit performance.

    Why single hose costs you capacity

    An air conditioner rejects heat outdoors. The condenser needs air to carry that heat away, and a single-hose portable takes that air from the room it is cooling, then pushes it out of the window.

    1. The unit blows conditioned room air across the condenser and out of the hose.
    2. That air leaves the house, so the room is now at slightly negative pressure.
    3. Air is pulled in from outdoors and adjoining spaces through gaps to equalise.
    4. The incoming air is hot and humid, which is exactly what the unit is trying to remove.

    A dual-hose design draws condenser air from outside through a second hose instead of from the room, which removes most of that penalty. It is the single most useful specification to check.

    Consideration Window unit Single-hose portable Dual-hose portable
    Condenser air source Outdoors The cooled room Outdoors
    Creates negative room pressure No Yes Largely no
    Needs a suitable window Yes, sash mount Vent kit only Vent kit only
    Federal efficiency metric CEER Portable AC standards Portable AC standards
    Where portables genuinely win

    Rooms with casement windows, rentals that prohibit window installation, spaces where a unit must be moved between rooms, and situations where nothing can be permanently mounted. In those cases the comparison is against no cooling at all, and the hose penalty is irrelevant.

    Room air conditioners just got a big standards increase

    Federal minimums for window and through-the-wall units rose sharply for products manufactured from May 26, 2026, by between 19% and 50% depending on class. That changes what is available new, and older stock built to the previous standard remains legal to sell. See our breakdown of the new CEER minimums.

    Frequently asked questions

    Are portable air conditioners less effective than window units?

    Single-hose portables are, for a structural reason: they exhaust conditioned room air outside, which pulls hot outdoor air in through gaps to replace it. A dual-hose design takes condenser air from outside instead and avoids most of that penalty. Window units do not have the problem at all.

    What is the difference between single-hose and dual-hose?

    A single hose exhausts air from the cooled room to outdoors, depressurising the room and drawing in unconditioned replacement air. A dual-hose unit draws condenser air from outdoors through a second hose, so it does not use room air for heat rejection. Dual hose is the more effective configuration.

    When is a portable air conditioner the right choice?

    Where a window unit cannot be fitted: casement windows, rentals prohibiting window installation, rooms needing occasional rather than continuous cooling, or spaces where nothing may be permanently mounted. In those cases the comparison is against no cooling, not against a window unit.

    Do portable air conditioners have efficiency standards?

    Yes, portable air conditioners are a separate regulated product class from room air conditioners under federal appliance standards, with their own metric. Window and through-the-wall units are rated on CEER, and those minimums rose substantially for units manufactured from May 26, 2026.

    Methodology and limitations

    Room air conditioner standards are quoted from 10 CFR 430.32(b). The single-hose explanation describes the physical mechanism of a negative pressure air balance, not a measured capacity penalty, because the size of that penalty depends on the specific room and building envelope.

    • We publish no percentage capacity loss for single-hose designs. It varies with room tightness and conditions.
    • We name no products and publish no efficiency figures for specific portable models.
    • Portable and room air conditioners are separate regulated classes with different metrics and are not directly comparable by rating.

    Sources

    1. US Department of Energy, 10 CFR 430.32(b), room air conditioner standards.

    The HVAC Brief is an independent trade publication. We do not sell equipment, take manufacturer advertising, or accept payment for placement in our research. Corrections welcome.

  • Gas Furnaces Must Hit 95% AFUE From December 2028

    Gas Furnaces Must Hit 95% AFUE From December 2028

    Last reviewed: August 2026 · By the HVAC Brief Editorial Team · Our sourcing and editorial standards

    The short answer

    Non-weatherized gas furnaces manufactured on or after December 18, 2028 must achieve 95% AFUE, up from the 80% minimum that has applied since November 19, 2015. Mobile home gas furnaces move to 95% on the same date.

    That jump effectively requires condensing furnaces, which vent differently from the 80% equipment most homes have. The venting change, not the efficiency change, is what makes this a retrofit problem.

    The date is more than two years out, which is exactly why it is worth planning for now. Furnaces installed today will still be in service, and houses being re-piped or renovated in the meantime can be made ready cheaply.

    The standard

    Product class Current minimum AFUE From December 18, 2028
    Non-weatherized gas furnaces 80.0% 95.0%
    Mobile home gas furnaces 80.0% 95.0%
    Weatherized gas furnaces 81.0% unchanged in this step
    Mobile home oil-fired furnaces 75.0% unchanged in this step

    AFUE is Annual Fuel Utilization Efficiency, the share of fuel energy delivered as useful heat across a heating season. An 80% furnace sends roughly a fifth of its fuel energy up the flue; a 95% furnace recovers most of that by condensing water vapour out of the exhaust.

    Why condensing changes the installation

    1. Exhaust is cooler and acidic. Condensing furnaces vent through plastic pipe rather than metal flue, because the exhaust no longer carries enough heat to drive a conventional chimney draught.
    2. A condensate drain is required. The water condensed out of the exhaust has to go somewhere, which means a drain the old installation never needed.
    3. Venting route may change. Plastic venting typically runs to a sidewall rather than up an existing chimney.
    4. Shared chimneys become a problem. Where a furnace and a water heater share a flue, removing the furnace can leave the water heater venting into an oversized chimney, which is its own hazard.
    The orphaned water heater problem

    This is the failure mode that catches people. In houses where an 80% furnace and an atmospheric gas water heater share a chimney, switching the furnace to sidewall venting leaves the water heater alone on a flue sized for two appliances. That can cause draught problems and requires the water heater venting to be reassessed as part of the job, not afterwards.

    What it means for planning

    The standard applies at manufacture, so 80% units built before the date remain legal to sell and install afterwards. The practical horizon is longer than the date suggests. But any house with a chimney-vented furnace will eventually face the venting conversion, and the cheapest time to deal with it is during other work rather than as an emergency replacement in January.

    Frequently asked questions

    When does the 95% AFUE furnace standard take effect?

    For non-weatherized gas furnaces and mobile home gas furnaces manufactured on or after December 18, 2028, per 10 CFR 430.32(e). The current minimum of 80% AFUE has applied to units manufactured since November 19, 2015.

    Does this ban 80% furnaces?

    It bars their manufacture from the effective date rather than their sale or use. Units built before December 18, 2028 remain legal to sell and install, and existing furnaces are unaffected. The practical transition is therefore longer than the date alone implies.

    Why do condensing furnaces need different venting?

    A 95% furnace extracts so much heat from the exhaust that the remaining flue gas is too cool to drive a conventional chimney draught, and it condenses into acidic water. That requires plastic venting, usually to a sidewall, and a condensate drain the older installation did not have.

    What is AFUE?

    Annual Fuel Utilization Efficiency, the proportion of fuel energy converted to useful heat across a heating season. An 80% furnace loses roughly a fifth of its fuel energy through the flue. A 95% furnace recovers most of that by condensing water vapour out of the exhaust stream.

    Methodology and limitations

    Standards and dates are quoted from 10 CFR 430.32(e), furnaces and boilers, retrieved from the electronic CFR.

    • The standard applies to manufacture date, not sale or installation date.
    • Venting descriptions state the mechanism. Specific venting requirements are set by manufacturer instructions and local mechanical code.
    • We publish no conversion cost. No federal series measures installed HVAC costs.
    • Nothing here is engineering advice for a specific installation.

    Sources

    1. US Department of Energy, 10 CFR 430.32(e), furnaces and boilers, via eCFR.

    The HVAC Brief is an independent trade publication. We do not sell equipment, take manufacturer advertising, or accept payment for placement in our research. Corrections welcome.

  • What Is R-454B? The A2L Refrigerant That Replaced R-410A

    What Is R-454B? The A2L Refrigerant That Replaced R-410A

    Last reviewed: August 2026 · By the HVAC Brief Editorial Team · Our sourcing and editorial standards

    The short answer

    R-454B is the refrigerant most manufacturers moved to for residential equipment after January 1, 2025, when federal rules barred new residential systems using refrigerant with a global warming potential of 700 or greater. R-410A has a GWP of 2,088.

    R-454B is classified A2L, meaning mildly flammable. That classification, not the GWP, is what changes how the refrigerant is stored, handled and installed.

    The transition is often described as a swap. It is not. The safety classification changed, and that has consequences for tooling, leak detection and equipment design that a like-for-like framing hides.

    What A2L means

    Refrigerant safety classification combines toxicity and flammability. The A denotes lower toxicity. The 2L denotes lower flammability with a low burning velocity, a category sitting between the non-flammable A1 refrigerants like R-410A and the more flammable A2 and A3 substances such as propane.

    Property R-410A R-454B
    Safety classification A1, non-flammable A2L, mildly flammable
    Global warming potential 2,088 Below the 700 threshold
    Permitted in new residential equipment No, since January 1, 2025 Yes
    Existing systems Legal to operate and service Not applicable

    What actually changes on a job

    1. Equipment is designed for it. A2L systems include mitigation features such as leak detection and airflow response. You do not convert an R-410A system by charging it with R-454B.
    2. Storage and transport requirements differ from A1 refrigerants, because the classification is different.
    3. Tooling and recovery equipment must be rated for A2L service.
    4. Training is the real gap. EPA 608 certification is unchanged, so a technician certified years ago remains certified without necessarily having A2L-specific training. See what 608 covers.
    5. Local code adoption varies. Building and mechanical codes govern where and how A2L equipment may be installed, and adoption is not uniform across jurisdictions.
    Mildly flammable is a classification, not a warning

    A2L refrigerants have a low burning velocity and require specific conditions to ignite, which is why they are permitted in occupied dwellings at all. The practical implication is procedural: rated tools, correct charge handling, and equipment designed with mitigation. It is a change in method, not a reason to avoid the equipment.

    What it does not change

    R-410A equipment already installed remains legal to operate and service, and pre-2025 inventory remains legally installable federally with no end date. Our summary of the installation rule covers that. What is changing on a published timetable is refrigerant availability, through the HFC phasedown.

    Frequently asked questions

    What is R-454B?

    The refrigerant most manufacturers adopted for residential air conditioners and heat pumps after federal rules barred new residential equipment using refrigerant with a global warming potential of 700 or greater from January 1, 2025. It is classified A2L, meaning lower toxicity and mild flammability, unlike the A1 classification of R-410A.

    Can I put R-454B in my R-410A system?

    No. A2L systems are designed with mitigation features and the equipment, tooling and charge characteristics differ. Retrofitting an R-410A system with an A2L refrigerant is not a supported procedure, and the existing system remains legal to service with R-410A.

    Is A2L refrigerant dangerous?

    A2L denotes lower toxicity and mild flammability with a low burning velocity, a class between non-flammable A1 refrigerants and more flammable A2 and A3 substances. It is permitted in occupied dwellings. The practical implication is procedural: rated tooling, correct handling and equipment with built-in mitigation.

    Do I need new certification for A2L refrigerants?

    EPA Section 608 certification requirements are unchanged, so an existing certification remains valid. What differs is training: A2L handling, storage and tooling requirements are not covered by a certification obtained before these refrigerants entered the market.

    Methodology and limitations

    The 700 GWP threshold and its January 1, 2025 date are from 40 CFR 84.54(a)(1). The R-410A global warming potential of 2,088 is the figure EPA used in that rulemaking. Safety classification descriptions follow the standard ASHRAE framework, which is a private standard we name but do not reproduce.

    • We do not publish a specific GWP figure for R-454B, only that it falls below the 700 threshold that governs eligibility.
    • Code adoption for A2L installation varies by jurisdiction and we do not summarise it.
    • Nothing here is engineering or safety guidance for a specific installation. Follow manufacturer instructions and local code.

    Sources

    1. US Environmental Protection Agency, 40 CFR 84.54, restrictions on the use of hydrofluorocarbons.
    2. US Environmental Protection Agency, 40 CFR 82.161, technician certification.

    The HVAC Brief is an independent trade publication. We do not sell equipment, take manufacturer advertising, or accept payment for placement in our research. Corrections welcome.

  • The 2026 Refrigerant Leak Rules Exclude Residential HVAC

    The 2026 Refrigerant Leak Rules Exclude Residential HVAC

    Last reviewed: August 2026 · By the HVAC Brief Editorial Team · Our sourcing and editorial standards

    The short answer

    New federal refrigerant leak repair requirements took effect on January 1, 2026, and residential and light commercial air conditioning and heat pumps are explicitly excluded from them.

    The rules at 40 CFR 84.106 apply to appliances with a full charge of 15 or more pounds. Your house does not have one. Commercial refrigeration, chillers and industrial process systems do.

    This distinction gets reported badly. Coverage of the leak rules often implies homeowners face new obligations. The regulation says otherwise, in terms, and knowing that saves arguments on both sides of a service call.

    What the rule actually covers

    Criterion Requirement
    Charge size Full charge of 15 or more pounds of refrigerant
    Substance A regulated substance, or a substitute with a global warming potential above 53
    Effective date January 1, 2026
    Excluded Residential and light commercial air conditioning and heat pump equipment
    Also excluded Appliances containing solely an ozone-depleting substance as refrigerant

    The exclusion is not an oversight or a grace period. It is written into the applicability paragraph at 40 CFR 84.106(a)(3)(ii).

    What the rule requires where it does apply

    1. Documentation on every service event. Anyone adding or removing refrigerant must give the owner or operator documentation meeting the rule’s requirements.
    2. Leak rate calculation. The owner or operator must calculate the leak rate every time refrigerant is added, with exceptions for retrofits, new installations and seasonal variance.
    3. Repair obligations triggered when calculated leak rates exceed thresholds set for the equipment type.
    4. Record keeping sufficient to demonstrate compliance.
    The part that does apply to a house

    Venting refrigerant is prohibited regardless of charge size or equipment type, and recovery requirements under 40 CFR part 82 apply to residential work. The leak repair and record keeping regime is what excludes residential equipment, not the handling rules. A technician still cannot vent, and still needs certification.

    Why a residential system that needs refrigerant still has a problem

    Regulatory exclusion is not an engineering exemption. A sealed circuit does not consume refrigerant, so a residential system needing a top up has a leak, and repeatedly recharging it treats the symptom while the underlying fault persists and the refrigerant escapes. See what different AC symptoms mean.

    Frequently asked questions

    Do the new refrigerant leak rules apply to home air conditioning?

    No. 40 CFR 84.106 applies to appliances with a full charge of 15 or more pounds, and paragraph (a)(3)(ii) explicitly excludes residential and light commercial air conditioning and heat pump equipment. The requirements took effect January 1, 2026 for the equipment they do cover.

    What size system is covered by the leak repair rule?

    Appliances with a full charge of 15 or more pounds of refrigerant, where the refrigerant is a regulated substance or a substitute with a global warming potential above 53. Residential and light commercial air conditioning and heat pumps are excluded regardless of charge.

    Can a technician still vent refrigerant from a home system?

    No. Venting prohibitions and recovery requirements under 40 CFR part 82 apply regardless of the leak repair rule’s applicability. The exclusion at 84.106 covers leak rate calculation, repair obligations and record keeping, not handling and venting rules.

    When did the leak repair requirements take effect?

    January 1, 2026, per 40 CFR 84.106(a)(4), for the equipment the section covers. Residential and light commercial air conditioning and heat pump equipment is excluded from the section entirely.

    Methodology and limitations

    Requirements are quoted from 40 CFR 84.106, leak repair, paragraph (a) applicability and paragraph (b) leak rate calculation, retrieved from the electronic CFR.

    • We summarise applicability rather than reproducing the full repair threshold and record keeping provisions.
    • Venting and recovery rules under 40 CFR part 82 are a separate regime and are not excluded for residential equipment.
    • Nothing here is legal advice on compliance for a specific installation or business.

    Sources

    1. US Environmental Protection Agency, 40 CFR 84.106, leak repair, via eCFR.
    2. US Environmental Protection Agency, 40 CFR part 82 subpart F, refrigerant handling and recovery.

    The HVAC Brief is an independent trade publication. We do not sell equipment, take manufacturer advertising, or accept payment for placement in our research. Corrections welcome.

  • EPA 608 Certification: Which Type HVAC Technicians Actually Need

    EPA 608 Certification: Which Type HVAC Technicians Actually Need

    Last reviewed: August 2026 · By the HVAC Brief Editorial Team · Our sourcing and editorial standards

    The short answer

    EPA Section 608 certification is federally required for anyone who maintains, services, repairs or disposes of appliances containing regulated refrigerants in a way that could violate the refrigerant circuit. Residential and light commercial HVAC work falls under Type II.

    There are four certifications, and they are defined by appliance pressure class rather than by job title. Apprentices are exempt while closely and continually supervised by a certified technician.

    The four certification types

    Certification Covers Typical residential relevance
    Type I Small appliances Window units, some packaged equipment
    Type II Medium, high and very high-pressure appliances, excluding small appliances and motor vehicle systems The one most residential HVAC work requires
    Type III Low-pressure appliances Chillers, rarely residential
    Universal All of the above Technicians working across equipment types

    Central residential air conditioners and heat pumps are medium or high-pressure appliances, which is why Type II is the practical requirement for most residential service work rather than Type I.

    Who is exempt, and who is not

    1. Apprentices are exempt while closely and continually supervised by a certified technician. Both the apprentice and the supervising technician carry responsibility for compliance.
    2. Disposal of small appliances and motor vehicle air conditioning does not require certification.
    3. Motor vehicle air conditioning service for consideration requires certification under 40 CFR part 82 subpart B, a separate scheme from 608.
    4. Everyone else performing work that could reasonably be expected to release refrigerant must hold the applicable certification.
    Certification is not a licence

    Section 608 is a federal environmental requirement about refrigerant handling. It is not a state contractor licence, does not authorise you to contract, and does not substitute for local licensing. The two are separate systems with separate requirements, and holding one says nothing about the other.

    Why the A2L transition raises the stakes

    The refrigerants replacing R-410A are classified A2L, meaning mildly flammable, which changes handling, storage and equipment requirements even though the certification framework is unchanged. A technician certified years ago holds a valid certification but may not have training on the refrigerants now shipping in new equipment. See our summary of the refrigerant rules.

    Frequently asked questions

    What EPA certification do HVAC technicians need?

    Type II for most residential and light commercial work, because central air conditioners and heat pumps are medium or high-pressure appliances. Type I covers small appliances, Type III covers low-pressure appliances, and Universal covers all three. The requirement is in 40 CFR 82.161.

    Do apprentices need EPA 608 certification?

    No, while closely and continually supervised by a certified technician. The regulation places responsibility for compliance on both the apprentice and the supervising technician. The exemption applies only during supervised work.

    Is EPA 608 the same as a contractor licence?

    No. Section 608 is a federal environmental certification covering refrigerant handling. Contractor licensing is set by states and municipalities and covers the right to contract for work. They are separate requirements and holding one does not satisfy the other.

    Does EPA 608 certification expire?

    The certification itself does not carry a federal renewal cycle in the way many state licences do. What changes is the equipment and refrigerants in the field: the A2L refrigerants now shipping have different handling requirements from R-410A, so currency of training matters separately from currency of certification.

    Methodology and limitations

    Requirements are quoted from 40 CFR 82.161, technician certification, paragraph (a), retrieved from the electronic CFR.

    • This covers the federal certification requirement only. State and local licensing is separate and varies.
    • We do not list exam providers, costs or study materials, as no federal source compiles them.
    • Nothing here is legal advice on compliance for a specific business.

    Sources

    1. US Environmental Protection Agency, 40 CFR 82.161, technician certification, via eCFR.

    The HVAC Brief is an independent trade publication. We do not sell equipment, take manufacturer advertising, or accept payment for placement in our research. Corrections welcome.

  • The HFC Phasedown Halves Again in 2029. Here Is the Schedule.

    The HFC Phasedown Halves Again in 2029. Here Is the Schedule.

    Last reviewed: August 2026 · By the HVAC Brief Editorial Team · Our sourcing and editorial standards

    The short answer

    US production and consumption of HFC refrigerants is capped on a declining schedule, and the next step is the largest: allowances halve from 60% of baseline to 30% on January 1, 2029. That is written into 40 CFR 84.7, not proposed.

    For anyone servicing R-410A equipment, that date matters more than any refrigerant rule already in force. The equipment stays legal to run; the refrigerant that keeps it running gets scarcer on a published timetable.

    The phasedown comes from the American Innovation and Manufacturing Act and is administered through an allowance system. Producers and importers may not exceed a set percentage of a fixed baseline, and that percentage steps down at defined dates.

    The schedule

    Period Production (% of baseline) Consumption (% of baseline) Production cap (MTEVe)
    2022-2023 90% 90% 344,299,157
    2024-2028 60% 60% 229,521,263
    2029-2033 30% 30% 114,760,632
    2034-2035 20% 20% 76,507,088
    2036 and after 15% 15% 57,380,316

    The production baseline is 382,535,439 metric tons of exchange value equivalent and the consumption baseline is 302,538,316. MTEVe weights each substance by its global warming potential, so a high-GWP refrigerant consumes more of the cap per physical pound than a low-GWP one.

    Why 2029 is the step that matters

    The move from 90% to 60% in 2024 was a 33% reduction. The move from 60% to 30% in 2029 is a 50% reduction, and it lands on a market still servicing a very large installed base of R-410A equipment.

    Because the cap is measured in exchange value equivalent rather than tonnes, high-GWP refrigerants are squeezed hardest. R-410A has a global warming potential of 2,088, so every pound produced consumes far more of the allowance pool than a pound of a low-GWP alternative.

    What this means for an R-410A system

    Nothing prohibits operating or servicing R-410A equipment, and pre-2025 inventory remains legally installable. What the schedule does is make the service refrigerant progressively scarcer against a fixed installed base. If you are advising a homeowner on a repair-or-replace decision for an R-410A system, the 2029 step belongs in the conversation. See what the installation rule actually says.

    Frequently asked questions

    When does the next HFC phasedown step happen?

    January 1, 2029, when production and consumption allowances drop from 60% of baseline to 30%, per the schedule in 40 CFR 84.7. It is the largest single step in the schedule, halving available allowances, and it follows the 2024 reduction from 90% to 60%.

    Will R-410A become unavailable?

    The regulation caps production and consumption rather than banning the substance, so it becomes scarcer rather than unavailable on a date. Because the cap is measured in exchange value equivalent, high-GWP refrigerants like R-410A at a GWP of 2,088 consume disproportionately more of the allowance pool.

    What is MTEVe?

    Metric tons of exchange value equivalent. It weights each regulated substance by its global warming potential, so the cap constrains climate impact rather than physical tonnage. A pound of a high-GWP refrigerant uses more of the allowance than a pound of a low-GWP one.

    Is it illegal to service R-410A equipment?

    No. The phasedown restricts production and import of the substance, not the servicing or operation of equipment that contains it. Existing systems remain legal to run and service, and reclaimed refrigerant is unaffected by production caps.

    Methodology and limitations

    All figures are quoted from 40 CFR 84.7, phasedown schedule, paragraphs (a) and (b), retrieved from the electronic CFR. The R-410A global warming potential of 2,088 is the figure EPA used in the Technology Transitions rulemaking.

    • The schedule constrains production and consumption allowances, not equipment operation or servicing.
    • We make no price forecast. The relationship between allowance reduction and market price is not something the regulation states.
    • Reclaimed refrigerant is treated differently from newly produced material under the rules.

    Sources

    1. US Environmental Protection Agency, 40 CFR 84.7, phasedown schedule, via eCFR.
    2. American Innovation and Manufacturing Act of 2020, as implemented at 40 CFR part 84.

    The HVAC Brief is an independent trade publication. We do not sell equipment, take manufacturer advertising, or accept payment for placement in our research. Corrections welcome.