Original data and independent reporting for the HVAC trade

Author: The HVAC Brief Editorial Team

  • Do Attic Fans Work? It Depends on Your Ceiling

    Do Attic Fans Work? It Depends on Your Ceiling

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

    The short answer

    A powered attic fan pulls air out of the attic, and where the ceiling below is not airtight, some of what it pulls is conditioned air from the house. That is the mechanism behind the long-running argument about them.

    Attic ventilation and attic fans are not the same thing. Passive ventilation through soffit and ridge vents moves air without a motor and without depressurising anything.

    Powered versus passive

    Passive ventilation Powered attic fan
    How air moves Buoyancy and wind, through soffit and ridge vents Motor driven extraction
    Uses electricity No Yes
    Depressurises the attic No Yes, which is the concern
    Risk if ceiling leaks None from the vent itself Can draw conditioned air up through leaks
    Risk with combustion appliances None from the vent itself Depressurisation near atmospheric appliances warrants care

    What determines whether a fan helps or hurts

    1. How airtight the ceiling plane is. Recessed lights, hatches, top plates and duct penetrations are the usual leaks. A sealed ceiling means the fan pulls outdoor air; a leaky one means it pulls some conditioned air.
    2. Whether intake ventilation is adequate. A fan without enough soffit intake will find its make-up air wherever it can, including the house.
    3. Whether ducts run through the attic. If they do, attic temperature affects the system directly, and the better answer is usually insulating and sealing those ducts. See why duct location matters.
    4. Whether combustion appliances share the space or are affected by pressure changes.
    The order that resolves the argument

    Seal the ceiling plane and insulate first. Once the boundary between house and attic is genuinely airtight, the objection to a powered fan largely disappears, because what it extracts is outdoor air. Installing the fan first, against a leaky ceiling, is what produces the outcomes people report as disappointing. See why envelope work comes first.

    Frequently asked questions

    Do attic fans actually work?

    They move air out of the attic, which is not disputed. The argument is about what replaces it. Where the ceiling below is not airtight, some make-up air comes from the conditioned house rather than from outside, which offsets the benefit. Sealing the ceiling plane first resolves most of that objection.

    What is the difference between an attic fan and attic ventilation?

    Passive ventilation moves air through soffit and ridge vents using buoyancy and wind, with no motor and no depressurisation. A powered attic fan extracts air mechanically, which lowers attic pressure and draws make-up air from wherever it can, including through leaks in the ceiling below.

    Will an attic fan lower my cooling bill?

    We publish no figure, because no federal source measures it at household level and the result depends on how airtight the ceiling is, how much intake ventilation exists, and whether ducts run through the attic. The mechanism can work, and it can also be offset by conditioned air being drawn upward.

    Should I insulate the attic or add a fan?

    Insulate and seal first. That reduces heat transfer through the ceiling and removes the pathway by which a fan could draw conditioned air upward. Once the ceiling plane is airtight, a fan extracts outdoor air rather than competing with your cooling system.

    Methodology and limitations

    This page describes the pressure mechanism rather than publishing performance figures, because no federal source measures attic fan performance at household level.

    • No energy saving percentage is claimed in either direction.
    • Depressurisation near atmospheric combustion appliances is a safety consideration requiring assessment of the specific installation.
    • Nothing here is engineering advice for a specific house.

    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.

  • Before the Heating Season: Two Safety Checks, Then the Rest

    Before the Heating Season: Two Safety Checks, Then the Rest

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

    The short answer

    The two checks worth doing before the heating season are the ones with a safety consequence: combustion venting and carbon monoxide alarms. Everything else on a seasonal list is comfort and efficiency.

    Timing matters more than the list. A fault found in October is a scheduled repair; the same fault found in January is an emergency call in the week everyone else is also calling.

    This is a task list, not a servicing interval. Our separate piece covers what the evidence actually supports on frequency, which is less than most service plans imply.

    The safety items

    1. Test carbon monoxide alarms and check their expiry date. Sensors age out, and an alarm past its service life is a decoration.
    2. Check the flue terminal is clear. Sidewall-vented condensing equipment can be blocked by snow, nests or debris, and a blocked flue stops the pressure switch proving draught. See how that shows up.
    3. Look for signs of a venting problem. Soot, corrosion at the flue connection, or condensation on windows when the furnace runs.
    4. Note any smell. Rotten egg or sulphur means leave and call the gas utility. See how to sort HVAC smells.

    The comfort and efficiency items

    Task Why Owner or technician
    Replace the filter Restricted airflow causes overheat cutouts and short cycling Owner
    Run the heat before you need it Finds faults in October rather than January Owner
    Clear registers and returns Furniture and rugs restrict airflow Owner
    Check thermostat mode and batteries Common cause of a no-heat call Owner
    Clear the outdoor unit for heat pumps Heat pumps need airflow across the coil in heating too Owner
    Static pressure and combustion check Requires instruments Technician
    The first-run smell is usually nothing

    Dust settled on the heat exchanger over the cooling season burns off at first use and typically clears within minutes. A burning smell that persists, or smells acrid, electrical or like hot plastic, is a different matter: shut the system down and have it inspected.

    What the season looks like going in

    Equipment producer prices set a series high in August 2026, and gas furnace shipments were down 6.2% year to date through June. Our season preview sets out where the published indicators stand. The practical read is that an emergency replacement this winter is a worse bargain than a planned one.

    Frequently asked questions

    What should I check before winter?

    Two safety items first: test carbon monoxide alarms and check their expiry date, and confirm the flue terminal is clear of snow, nests and debris. Then run the heat before you need it, replace the filter, clear registers and returns, and check thermostat mode and batteries.

    Why does my furnace smell when I first turn it on?

    Dust that settled on the heat exchanger during the cooling season burning off, which typically clears within minutes. A persistent burning smell, or one that is acrid, electrical or like hot plastic, is different and warrants shutting the system down and having it inspected.

    Do heat pumps need seasonal preparation too?

    Yes, and the outdoor unit matters in winter as well as summer. A heat pump extracts heat from outdoor air, so airflow across the outdoor coil is required in heating mode. Keep the unit clear of vegetation, drifted snow and stored items.

    Should I book a service before winter?

    The instrument-based checks, combustion analysis and static pressure, require a technician. Whether an annual visit is warranted is a separate question from whether these seasonal checks are, and the evidence on servicing intervals is weaker than most service plans suggest.

    Methodology and limitations

    This page separates safety items from comfort items. We publish no service interval recommendation, as no federal source sets or measures one.

    • Combustion safety concerns are not maintenance items and should not be deferred.
    • Manufacturer warranty terms may require documented maintenance, which is contractual rather than regulatory.
    • Nothing here is engineering or safety advice for a specific system.

    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 Should Happen on HVAC Installation Day

    What Should Happen on HVAC Installation Day

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

    The short answer

    A correct installation includes a load calculation, a permit where the jurisdiction requires one, and a commissioning step where the installer measures the system rather than assuming it. The measuring is the part most often skipped, and it is the part that determines whether you got what you paid for.

    Most of what separates a good install from a poor one is invisible once the panels are back on, which is why it is worth agreeing the checklist beforehand.

    What should happen, in order

    1. Load calculation before equipment is ordered. Capacity should follow from a room-by-room calculation, not from the size of the old unit. See why that matters.
    2. Permit application where required. Requirements vary by jurisdiction, and permitted work is inspected work.
    3. Duct evaluation. Static pressure measured before the new equipment goes on, so the ductwork is not silently inherited as a constraint.
    4. Removal and recovery. Refrigerant recovered, not vented. This is a federal requirement under 40 CFR part 82 regardless of system size.
    5. Installation and line set decisions. Whether existing line sets are reused, flushed or replaced should be stated, not assumed.
    6. Commissioning. Charge verified by measurement, airflow measured, static pressure rechecked, and the results written down.
    7. Documentation handed over. Load calculation, commissioning readings, warranty registration and permit sign-off.

    What to get in writing before work starts

    Item Why it matters
    Equipment and labour as separate lines Equipment is the line that has moved most since 2019
    Whether ductwork is included The usual reason one quote is far below the others
    Refrigerant type Pre-2025 R-410A inventory is cheaper and legally installable, with a phasedown attached
    Line set treatment Reuse, flush or replace changes both cost and risk
    Permit responsibility Who applies, who pays, who schedules inspection
    Commissioning readings Written proof the system was measured, not assumed
    Warranty registration Often required within a window or the term shortens. See what warranties cover
    The single best question

    Ask what the measured airflow and static pressure were after commissioning, and ask for the numbers. An installer who measures will have them. One who does not will explain why they are unnecessary, and that answer tells you what kind of installation you bought.

    Frequently asked questions

    What should happen during an HVAC installation?

    A load calculation before equipment is ordered, a permit where the jurisdiction requires one, duct evaluation including static pressure, refrigerant recovery rather than venting during removal, a stated decision on line sets, and commissioning where charge and airflow are measured and written down.

    Do I need a permit to replace an HVAC system?

    Requirements vary by jurisdiction and we cannot state a universal answer. Where a permit is required, permitted work is inspected work, which is a check on the installation you otherwise have no way to obtain. Agree in advance who applies, who pays and who schedules the inspection.

    Can the installer reuse my existing line set?

    Sometimes, depending on condition, sizing and the refrigerant involved. What matters is that the decision is stated rather than assumed: reuse, flush or replace each carry different cost and risk. Ask which was done and why before work starts rather than afterwards.

    How do I know the installation was done correctly?

    Ask for the commissioning readings: measured airflow, static pressure and verified charge, in writing. An installer who measures will have the numbers. Most of what distinguishes a good installation is invisible once the panels are back on, which is why written readings matter.

    Methodology and limitations

    Refrigerant recovery requirements are from 40 CFR part 82. Load calculation procedure is ACCA Manual J, a private standard we name but do not reproduce.

    • Permit requirements vary by jurisdiction and we do not summarise them. Confirm locally.
    • We publish no installation costs or durations, as no federal series measures them.
    • Nothing here is engineering advice for a specific installation.

    Sources

    1. US Environmental Protection Agency, 40 CFR part 82 subpart F, refrigerant recovery and 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.

  • Insulate First, Then Size the System. Not the Other Way Round.

    Insulate First, Then Size the System. Not the Other Way Round.

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

    The short answer

    Sealing and insulating reduces the load the equipment has to meet, which is the only intervention that makes a smaller system the correct answer rather than a compromise. Upgrading equipment against an unchanged load buys efficiency per unit of work, not less work.

    The sequencing matters because load calculation drives sizing. Do the envelope after the equipment and you have sized for a load that no longer exists.

    Why order changes the outcome

    Sequence What happens
    Envelope first, then equipment Load calculation reflects the improved house; equipment sized correctly for it
    Equipment first, then envelope System now oversized for the reduced load, short cycles, dehumidifies poorly
    Equipment only Same load met more efficiently; comfort problems from leakage remain
    Envelope only Load falls, existing system becomes oversized for it

    The second row is the expensive mistake. Improving the envelope after installing new equipment converts a correctly sized system into an oversized one, which is the mechanism behind cool but clammy houses. See why oversizing causes that.

    What actually drives the load

    1. Air leakage. Uncontrolled exchange through the envelope, worst at the top and bottom of the house where stack effect is strongest.
    2. Attic insulation. Usually the largest single surface exposed to extreme temperature.
    3. Window area and orientation. Often the largest cooling variable, and expensive to change.
    4. Duct location. Ductwork in an unconditioned attic exchanges heat with that space along its whole length. See why that matters.
    5. Duct leakage. Conditioned air delivered to an attic is paid for and lost.

    Items one, two, four and five are usually cheaper to address than the equipment, and they reduce the load rather than serving it more efficiently.

    The awkward implication

    A genuinely improved envelope means the replacement system should be smaller than the one coming out. Homeowners often read a smaller tonnage as being sold less, and contractors know it. Ask for the load calculation that produced the number, and treat a like-for-like swap after envelope work as a question rather than a default. See why sizing by rule of thumb fails.

    Frequently asked questions

    Should I insulate before replacing my HVAC?

    Generally yes, because sealing and insulating reduce the load the equipment must meet, and load calculation drives correct sizing. Doing the envelope afterwards leaves a system sized for a load that no longer exists, which produces short cycling and poor dehumidification.

    Will insulation reduce my energy bills?

    It reduces the load, which reduces run hours, which reduces consumption. We publish no percentage, because the result depends on the existing envelope, climate and how the house is used, and no federal source measures it at household level. The mechanism is well established even where the magnitude is house specific.

    Is a smaller HVAC system after insulating a downgrade?

    No, it is the correct consequence. A reduced load calls for reduced capacity, and installing the previous size against a smaller load produces an oversized system that short cycles and dehumidifies poorly. Ask for the load calculation supporting whatever capacity is proposed.

    What should I address first?

    Air leakage and attic insulation are usually the largest and least expensive levers, followed by duct location and duct leakage where ductwork runs through unconditioned space. Window replacement addresses a real load driver but is normally the most expensive route to it.

    Methodology and limitations

    This page describes the relationship between building load and equipment sizing. We publish no savings percentages, as no federal source measures household level results for envelope work.

    • No percentage saving is claimed for any measure.
    • Load calculation procedure is ACCA Manual J, a private standard we name but do not reproduce.
    • Nothing here is engineering advice for a specific house.

    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.

  • Commercial HVAC vs Residential: The Three Real Differences

    Commercial HVAC vs Residential: The Three Real Differences

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

    The short answer

    Commercial HVAC differs from residential in three ways that matter: equipment sits on the roof as packaged units, ventilation is code-driven rather than optional, and the regulatory treatment is different.

    That last point is concrete. The 2026 refrigerant leak repair rules at 40 CFR 84.106 apply at 15 or more pounds of charge and exclude residential and light commercial equipment, so larger commercial systems carry obligations a house never does.

    The three real differences

    Residential Commercial
    Typical equipment Split system, indoor and outdoor units Packaged rooftop units, or chillers at larger scale
    Ventilation Often incidental, through envelope leakage Specified outdoor air rates, code driven
    Zoning Optional, added with dampers Usually inherent, multiple units or VAV
    Refrigerant leak rules Excluded from 40 CFR 84.106 Apply at 15+ lb charge
    Access Ground level or basement Roof, with access and safety implications
    Downtime cost Comfort Often revenue, sometimes stock or process

    Why rooftop packaged units dominate

    1. No indoor plant space consumed, which is leasable floor area in a commercial building.
    2. Modularity. Several units serving zones is more resilient than one large machine, and a failure takes out part of the building rather than all of it.
    3. Service access without entering tenant space, which matters in multi-tenant buildings.
    4. Simpler outdoor air provision, since the unit is already outside.

    The trade-off is exposure: rooftop equipment weathers harder, and access requires fall protection and often a lift.

    The regulatory line that catches contractors

    The 15-pound charge threshold in 40 CFR 84.106 is what separates a system with leak rate calculation and record-keeping obligations from one without. Light commercial air conditioning and heat pumps are excluded alongside residential, but larger commercial and refrigeration systems are not. See who those rules cover.

    Where the VRF dates matter

    Variable refrigerant flow systems, common in commercial and light commercial work, have their own timetable under 40 CFR 84.54(c)(2): restricted from January 1, 2026, installable before January 1, 2027 where components were built before January 1, 2026, and before January 1, 2028 with a building permit issued prior to October 5, 2023. Our compliance calendar sets out the dated sequence.

    Frequently asked questions

    What is the difference between commercial and residential HVAC?

    Equipment is typically packaged rooftop units rather than split systems, ventilation rates are specified by code rather than incidental, and larger systems carry refrigerant obligations residential equipment does not. The 2026 leak repair rules apply at 15 or more pounds of charge and exclude residential and light commercial air conditioning.

    Why is commercial HVAC on the roof?

    Because indoor plant space is leasable floor area, several modular units are more resilient than one large machine, service access does not require entering tenant space, and outdoor air provision is simpler when the unit is already outside. The trade-off is weather exposure and access requirements.

    Do refrigerant leak rules apply to commercial systems?

    To larger ones, yes. 40 CFR 84.106 applies to appliances with a full charge of 15 or more pounds, with leak rate calculation, repair obligations and record keeping. Residential and light commercial air conditioning and heat pumps are explicitly excluded from the section.

    What is a VRF system?

    Variable refrigerant flow, a system where one outdoor unit serves multiple indoor units with modulating refrigerant flow, common in commercial and light commercial buildings. It has its own restriction timetable under 40 CFR 84.54(c)(2), separate from the rules covering residential split systems.

    Methodology and limitations

    Regulatory positions are quoted from 40 CFR 84.106 and 40 CFR 84.54. Equipment descriptions are general architecture rather than any specific manufacturer’s product.

    • Ventilation rate requirements are set by building and mechanical codes that vary by jurisdiction, and we do not summarise them.
    • We publish no commercial equipment or service costs, as no federal series measures them.
    • Nothing here is engineering or compliance advice for a specific building.

    Sources

    1. US Environmental Protection Agency, 40 CFR 84.106 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.

  • What an HVAC Warranty Actually Covers, and What It Does Not

    What an HVAC Warranty Actually Covers, and What It Does Not

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

    The short answer

    An HVAC warranty usually covers the part and not the labour to fit it, and registration is often required within a set window after installation or the term drops. Those two details decide most of what a warranty is actually worth.

    Manufacturer parts warranty, contractor labour warranty and a third-party home warranty are three different products. They get discussed as one thing and they fail in different ways.

    The three things called a warranty

    Type Who provides it Typically covers Typically excludes
    Manufacturer parts warranty Equipment maker The failed component Labour, refrigerant, diagnostics, travel
    Contractor labour warranty The installing company Labour for a defined period Parts, and it ends if the company does
    Home warranty or service contract Third party Varies by contract Varies by contract, often pre-existing faults

    A parts warranty on a compressor sounds substantial until you price the labour, the refrigerant recovery and the recharge that fitting it requires, none of which the parts warranty pays.

    What most often voids or shortens coverage

    1. Not registering. Many manufacturers require registration within a window after installation, and the unregistered term is shorter.
    2. Unlicensed or DIY installation. Coverage commonly requires installation by a qualified contractor.
    3. No documented maintenance. Some terms require evidence of servicing, which is a contractual requirement rather than a federal one. See what the evidence says about intervals.
    4. Non-original parts. Substituting components can void remaining coverage.
    5. Transfer on sale. Some warranties transfer to a new owner, some do not, and some require a fee and a form within a window.
    The question that reveals the real value

    Ask what a covered compressor failure would cost you out of pocket. If the answer includes diagnostic time, labour, refrigerant recovery and recharge, you have learned what the warranty does not cover, which is the part that matters. On an R-410A system the refrigerant line of that answer gets less comfortable each year under the phasedown schedule.

    Frequently asked questions

    Does an HVAC warranty cover labour?

    Usually not. A manufacturer parts warranty typically covers the failed component only, leaving diagnostic time, labour, refrigerant recovery and recharge to the owner. Labour coverage normally comes separately from the installing contractor, for a shorter defined period, and it ends if that company ceases trading.

    Do I need to register my HVAC warranty?

    Often yes, and within a limited window after installation. Many manufacturers offer a longer term to registered owners and a shorter default term to everyone else. Registration is one of the most common reasons a warranty turns out to be shorter than the owner believed.

    What voids an HVAC warranty?

    Common causes are failing to register in time, installation by an unqualified party, absence of documented maintenance where the terms require it, and substituting non-original parts. Transfer rules on sale also vary, with some warranties requiring a fee and a form within a window.

    Is a home warranty worth it for HVAC?

    That depends entirely on the contract, and no federal source measures the value of these products. Read what is excluded rather than what is covered, check how pre-existing conditions are defined, and confirm who chooses the contractor and what the payout limits are per claim and per year.

    Methodology and limitations

    This page describes contract structures in general terms. Warranty terms are private contracts and vary by manufacturer, contractor and provider.

    • We name no manufacturers or warranty providers and rate none.
    • No federal source measures warranty claim rates or the value of service contracts.
    • Nothing here is legal advice. Your specific terms govern, and consumer protection rules vary by state.

    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.

  • HVAC Financing: What to Establish Before You Sign

    HVAC Financing: What to Establish Before You Sign

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

    The short answer

    HVAC financing became a bigger part of the decision after the federal 25C tax credit expired for anything placed in service after December 31, 2025, removing up to $2,000 from a qualifying heat pump job.

    Equipment producer prices are also up 60% since 2019. A larger bill with no federal credit against it is why payment structure now comes up earlier in the conversation than it used to.

    We do not compare lenders or rate offers. What follows is what to establish before signing, and which numbers are documented.

    What changed on the incentive side

    Factor 2025 2026
    Federal 25C credit, qualifying heat pump Up to $2,000 $0
    What controls eligibility Placed in service by Dec 31, 2025 Not available
    State and utility rebates Unaffected Unaffected
    Equipment producer prices vs 2019 Up 60%, July 2026 the series high

    Details of the credit expiry are in what the 25C change costs, and the price trend in our price index analysis.

    What to establish before signing

    1. The total amount repayable, not the monthly figure. Two offers with the same monthly payment over different terms are not the same offer.
    2. The annual percentage rate, and whether any promotional rate expires into a higher one.
    3. Whether deferred interest applies. Some promotional structures charge interest retrospectively from day one if the balance is not cleared within the promotional window.
    4. Any dealer fee built into the price. A financed price and a cash price are sometimes different numbers for the same job.
    5. Whether the obligation attaches to you or the property. Some programmes secure the debt against the home, which affects sale and refinancing.
    6. Early repayment terms, including whether paying early reduces total interest.
    Check rebates before financing

    State and utility rebate programmes were not affected by the federal credit expiring, and they vary by utility rather than by state, so a neighbouring town can have a materially different offer. Establishing what is available reduces the amount financed, which changes every other number in the deal. Confirm with the specific utility rather than assuming.

    Frequently asked questions

    Is there still a tax credit for HVAC in 2026?

    Not federally. The Section 25C Energy Efficient Home Improvement Credit applied to property placed in service before December 31, 2025, and installation date controls rather than purchase date. State and utility rebate programmes are separate and were unaffected by that expiry.

    What should I check in an HVAC financing offer?

    The total amount repayable rather than the monthly payment, the annual percentage rate and whether a promotional rate expires, whether deferred interest applies retrospectively, any dealer fee built into the financed price, whether the obligation attaches to the property, and early repayment terms.

    What is deferred interest?

    A promotional structure where interest accrues from the start but is only charged if the balance is not cleared within the promotional period. Clearing it in time costs nothing; missing the window by a small amount can trigger interest calculated back to day one on the original balance.

    Why did HVAC costs rise so much?

    Equipment producer prices are up about 60% since 2019, roughly twice general consumer inflation, with August 2026 the highest reading in the BLS series. The federal 25C credit worth up to $2,000 also expired for installations after December 31, 2025.

    Methodology and limitations

    Credit terms are from the IRS. Equipment price movement is BLS series PCU333415333415 indexed to its 2019 annual average.

    • We name no lenders and compare no rate offers.
    • Nothing here is financial advice. Terms vary by provider, product and jurisdiction, and consumer credit rules differ by state.
    • We publish no installed costs, as no federal series measures them.

    Sources

    1. Internal Revenue Service, Energy Efficient Home Improvement Credit.
    2. US Bureau of Labor Statistics, Producer Price Index series PCU333415333415.

    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.

  • UV Lights and Air Purifiers: The Questions Marketing Skips

    UV Lights and Air Purifiers: The Questions Marketing Skips

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

    The short answer

    In-duct UV lights and add-on air cleaners are sold with performance claims that no federal agency verifies, and the numbers quoted come from manufacturer testing rather than an independent standard.

    That does not make them useless. It means the burden is on the seller to say what was tested, under what conditions, and by whom, and most marketing does not.

    Two different products get sold together and they do different things. Filtration removes particles from circulating air. UV is intended to act on biological growth. Neither exchanges air with outdoors, which is the thing people often actually want.

    What each product category actually does

    Product Intended action What it does not do
    Coil UV light Irradiates the evaporator coil surface to limit growth on it Does not treat air passing at duct velocity
    In-duct air UV Irradiates air in the duct stream Effectiveness depends heavily on exposure time and dose
    Media air cleaner Higher surface area filtration Does not exchange air, and adds pressure drop
    Electronic air cleaner Charges and collects particles Requires cleaning to keep working
    Ventilator (ERV/HRV) Actually exchanges indoor and outdoor air Not a filtration product

    If the goal is fresh air rather than cleaner recirculated air, none of the first four addresses it. See what ventilation actually means.

    The questions that separate a product from a claim

    1. What was tested, the coil or the airstream? A lamp sized to keep a coil clean is not the same as one intended to treat moving air.
    2. At what airflow? UV dose depends on exposure time. A result at low velocity does not transfer to a system moving air at duct speed.
    3. Tested by whom, against what standard? Manufacturer laboratory results are not independent verification.
    4. What is the pressure drop? Any added filtration raises static pressure, which reduces airflow. See why filter choice affects airflow.
    5. What is the maintenance cycle? Lamps lose output over time and cells need cleaning; an unmaintained device is decorative.
    The one thing UV reliably addresses

    A coil that stays damp between cycles grows biological material, which is the usual source of musty odour. A lamp aimed at that coil targets a real and specific problem. Whether the same lamp does anything useful to air moving past it at duct velocity is a separate question with a separate answer. See what musty smells actually indicate.

    Frequently asked questions

    Do UV lights in HVAC systems work?

    A lamp aimed at the evaporator coil addresses growth on that coil, which is a real and specific problem and the usual source of musty odour. Claims about treating air moving through the duct are a separate question, because effectiveness depends on dose and exposure time at duct velocity. No federal agency verifies these performance claims.

    Are air purifiers worth adding to HVAC?

    It depends what problem you are solving. Added filtration removes more particles from recirculating air and also increases pressure drop, reducing airflow. Neither filtration nor UV exchanges indoor air with outdoor air, so if the concern is fresh air, a ventilator rather than a purifier is the relevant product.

    Why do performance claims vary so much between products?

    Because there is no single federal standard verifying them. Figures come from manufacturer testing under conditions the marketing rarely states, and results depend heavily on airflow, dose, chamber size and what was actually measured. Ask what was tested, at what airflow, and by whom.

    Will an air cleaner reduce my energy use?

    Not directly, and denser filtration usually increases blower energy by raising static pressure. A clean coil does help the system run as designed, which is the mechanism behind coil-focused UV, but that is a maintenance benefit rather than an efficiency product.

    Methodology and limitations

    This page describes product categories and the questions that distinguish tested performance from marketing. We publish no efficacy figures, because no federal source verifies them and manufacturer results are not comparable across products.

    • No product is named, recommended or criticised. We do not review equipment.
    • No efficacy percentage is quoted for any device.
    • Health claims are outside our scope. Nothing here is medical or air quality advice.

    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.

  • Your AC Does Not Need a Recharge. It Has a Leak.

    Your AC Does Not Need a Recharge. It Has a Leak.

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

    The short answer

    Air conditioners do not consume refrigerant, so a system that needs recharging has a leak. Recharging without finding that leak restores cooling temporarily while the refrigerant escapes again.

    That matters more than it used to. Under the federal HFC phasedown, production allowances drop from 60% of baseline to 30% on January 1, 2029, so refrigerant for older systems gets scarcer on a published timetable.

    The phrase “needs a recharge” describes a symptom as though it were routine maintenance. It is not routine, and treating it that way is how a small leak becomes an annual bill.

    Why a sealed system should never need topping up

    Refrigerant circulates in a closed loop, changing state between liquid and vapour. Nothing in normal operation consumes it. If the charge is low, it left through a physical opening: a failed joint, a corroded coil, a service valve, or a crack.

    What you are told What it means
    “It just needs a recharge” The system has a leak that has not been located
    “It is low on Freon” Same, with a brand name that identifies nothing. See why Freon is not a type
    “They all lose a bit over time” Not true of a sealed circuit in normal operation
    “We topped it up last year too” An unrepaired leak, now with two charges vented

    What to ask before authorising a recharge

    1. Where is the leak? A leak search is a distinct diagnostic step, not something inferred from low pressure.
    2. How much refrigerant is going in? A large charge on a residential system indicates a significant loss.
    3. What refrigerant is it? R-22 has not been produced since January 1, 2020, so it comes from reclaimed stock. See what remains of R-22.
    4. What happens when it recurs? Get the plan in writing, including whether the repair is worth doing against replacement.
    5. Is the repair economic? A leaking evaporator coil on an older R-410A system often decides the replace-or-repair question by itself.
    The regulatory position

    Venting refrigerant is prohibited under 40 CFR part 82, and technicians handling it must hold EPA Section 608 certification. Notably, the 2026 leak repair rules at 40 CFR 84.106 apply at 15 or more pounds of charge and explicitly exclude residential equipment, so there is no federal record-keeping obligation on a home system. That is a regulatory exemption, not an engineering one. See who those rules actually cover.

    Frequently asked questions

    Does an air conditioner need refrigerant recharged regularly?

    No. Refrigerant circulates in a sealed loop and is not consumed by normal operation, so a system that is low has lost it through a leak. Regular topping up is not maintenance, it is an unrepaired fault being managed rather than fixed.

    How much does an AC recharge cost?

    No federal series tracks residential refrigerant or repair pricing, so any figure quoted is a vendor estimate rather than measured data. What is documented is that HFC production allowances drop from 60% of baseline to 30% on January 1, 2029, which constrains supply for older systems over time.

    Why does my AC keep losing refrigerant?

    Because the leak was never located and repaired. Common sites are the evaporator coil, brazed joints, service valves and line set connections. Each recharge restores cooling until enough has escaped again, and each one vents a controlled substance into the atmosphere.

    Is it worth repairing a refrigerant leak?

    It depends where the leak is and what the system is worth. An accessible joint is usually a straightforward repair. A leaking evaporator coil on an older R-410A system often decides replacement instead, because the part, the labour and the recovery and recharge all land together.

    Methodology and limitations

    Regulatory positions are from 40 CFR part 82 for venting and certification, 40 CFR 84.106 for leak repair applicability, and 40 CFR 84.7 for the phasedown schedule.

    • We publish no recharge or repair prices, as no federal series measures them.
    • Leak location and repair economics are system specific.
    • Refrigerant work requires EPA Section 608 certification and is not owner serviceable.

    Sources

    1. US Environmental Protection Agency, 40 CFR part 82 subpart F; 40 CFR 84.106; 40 CFR 84.7.

    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 Air Conditioning Costs to Run, and Why No National Figure Works

    What Air Conditioning Costs to Run, and Why No National Figure Works

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

    The short answer

    There is no useful national figure for what air conditioning costs to run, because residential electricity prices vary about 4-fold across US states. The US average was 18.34 cents per kilowatt hour in June 2026, but Nevada was 13.11 and Hawaii was 52.72.

    Running cost is your rate multiplied by your consumption. Anyone quoting a dollars-per-month figure without knowing your rate is guessing at the larger of the two variables.

    The calculation itself is simple. What makes published estimates unreliable is that they fix a rate you almost certainly do not pay.

    What electricity actually costs, by state

    State June 2026 (cents/kWh) June 2025 Change
    US average 18.34 17.47 +5.0%
    Hawaii 52.72 40.96 +28.7%
    California 34.74 33.59 +3.4%
    Massachusetts 29.61 30.33 -2.4%
    New York 29.49 26.55 +11.1%
    Illinois 19.89 18.29 +8.7%
    Ohio 19.19 17.50 +9.7%
    Georgia 16.36 15.96 +2.5%
    Texas 15.94 15.26 +4.5%
    Florida 15.10 15.35 -1.6%
    Louisiana 13.49 12.74 +5.9%
    Nevada 13.11 12.26 +6.9%

    Residential prices rose 5.0% nationally against June 2025, but the change was far from uniform: some states rose by double digits while others fell.

    How to work out your own number

    1. Find your rate. Divide the total electricity charge on your bill by the kilowatt hours used. Do not use the headline supply rate, which excludes delivery charges that are often a third or more of the bill.
    2. Find the equipment draw. The data plate on the outdoor unit states electrical characteristics. A technician can measure actual running amps, which is more useful than nameplate.
    3. Estimate run hours. This is the variable nobody else can supply. It depends on climate, insulation, sizing and thermostat behaviour.
    4. Multiply. Kilowatts multiplied by run hours multiplied by your rate.

    The third step is why published averages fail. Two identical houses in the same city with different insulation and different thermostat habits can differ by a factor of two in run hours.

    Efficiency ratings compare equipment, not bills

    SEER2 describes how much cooling a machine delivers per unit of electricity under standard test conditions. It does not tell you what your bill will be, because it says nothing about your rate, your climate or your run hours. A high SEER2 system in Hawaii can cost more to run than a low SEER2 system in Nevada. See our guide to SEER2 minimums.

    What actually moves the number

    Run time is the lever, and most of what determines it sits outside the equipment. A correctly sized system in a well sealed house with sound ductwork runs fewer hours than an oversized system in a leaky one, regardless of the rating on either.

    Our guides on sizing and ductwork and airflow cover the two that most often go wrong.

    Frequently asked questions

    How much does it cost to run air conditioning per month?

    There is no reliable national figure, because residential electricity rates vary roughly 4-fold between states. The US average was 18.34 cents per kilowatt hour in June 2026, against 13.11 in Nevada and 52.72 in Hawaii. Your cost is your rate multiplied by your consumption, and both are local.

    What is the average electricity price in the US?

    18.34 cents per kilowatt hour for residential customers in June 2026, up 5.0% from 17.47 cents in June 2025, per the EIA Electric Power Monthly. State averages ranged from 13.11 cents in Nevada to 52.72 cents in Hawaii.

    Does a higher SEER2 rating lower my bill?

    It lowers the electricity needed per unit of cooling under standard test conditions, but your bill depends on your rate, your climate and your run hours as well. A high efficiency system in an expensive electricity market can cost more to run than a lower efficiency one in a cheap market.

    How do I calculate my own running cost?

    Divide the total electricity charge on your bill by kilowatt hours used to get your true rate including delivery, find the equipment’s electrical draw from the data plate or a measured reading, estimate run hours for your climate and house, then multiply the three. Run hours is the variable published estimates cannot know.

    Methodology and limitations

    Electricity prices are the US Energy Information Administration Electric Power Monthly, Table 5.6.A, average price of electricity to ultimate customers by end-use sector and state, residential column, June 2026 and June 2025, released August 26, 2026.

    • These are state averages. Utility territories within a state differ, and time-of-use tariffs differ again.
    • We publish no dollars-per-month running cost, because run hours cannot be known from published data.
    • Data plate figures describe rated draw, not measured operating draw.

    Sources

    1. US Energy Information Administration, Electric Power Monthly, Table 5.6.A, June 2026, released August 26, 2026.
    2. US Department of Energy, 10 CFR 430.32, efficiency 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.