20 X 24 X 1 Merv 6 Fiberglass Air Filter Reviews
The research
- Who this is for
- What is a MERV rating?
- How to choose a filter by its MERV rating
- A perfectly adept HVAC filter: Nordic Pure MERV 12
- Ii other filters that should practise a fine job
- How often should I replace my filters during wildfire smoke events?
- Footnotes
Who this is for
Most HVAC systems utilize a standard 1-inch-thick filter, so we focused exclusively on 1-inch medium-efficiency MERV filters. These are installed either in wall-mounted air-render vents (most common in the South), or at the air handler (more common in the Mid-Atlantic and northern states, where the air handler is often placed in the basement, near the furnace). A correctly sized 1-inch MERV filter only rests behind a bracket at the render annals; if you lot're not certain what size y'all need, bank check the narrow side of an existing filter for the dimensions (similar "16 x 25 x i").
If your HVAC organization uses a thicker filter (unremarkably in the iv- to 5-inch range, and ordinarily mounted at the air handler), information technology was likely designed specifically for medium-efficiency MERV filtration. Y'all don't need our advice; simply supplant the existing filter with 1 that has the same specs.
What is a MERV rating?
MERV stands for Minimum Efficiency Reporting Value, and is a mensurate of how well a filter removes particulates from the air. In that manner it'due south alike to the more familiar HEPA rating used on air purifiers. And like the test for HEPA rating, MERV testing measure a filter's efficiency—the pct of particles information technology captures—in a single pass. Air is loaded with particulate matter, sent through the filter a single time, and the results measured. In real-globe apply, with the air in your home constantly recirculating through the ducts and passing through the filters each time, the cumulative effect of the filters rises.
Simply MERV is different in some key ways. First, instead of beingness a simple pass-fail measure like HEPA (a filter is either HEPA-rated or information technology's not), MERV ratings fall on a scale from 1 to xvi, with higher numbers indicating ameliorate functioning.
Also unlike HEPA, MERV tests measure particulates of dissimilar sizes, from 0.3 micron (very small and hard to filter—the size HEPA tests measure) upwards to 10 microns (relatively large and piece of cake to filter). MERV also doesn't have a target percentage for removal, the way HEPA does. Instead, the actual percent removal is recorded for each of 12 particle sizes, and these numbers are referenced against a functioning table to determine the appropriate rating.
And so when yous look at the full spectrum of what'south floating around in the air in your house, MERV ratings reflect a filter's operation on all of it. Higher numbers signal a better filtration of the smaller particles, similar pollen and smoke, that cause many respiratory bug. And medium-efficiency MERV filters in the viii to thirteen range—the kind we would get—can remove 90 percent or more of these. (For a really thorough explanation of how MERV ratings are calculated, visit the website of the National Air Filtration Association.)
I more thing: Some companies, including major filter manufacturer 3M/Filtrete and major filter retailer Home Depot, use their ain rating conventions (MPR by Filtrete and FPR past Home Depot). Both claim to be based on the American Social club of Heating, Refrigeration, and Ac Engineers'south ASHRAE 52.2 standard that'south used to set up MERV ratings, but neither company provides an easily accessible explanation of how its own ratings differ from or compare with MERV. (Filtrete does print MPR and MERV equivalents on the frames of its filters, but you lot can't see that until you've really got one in your hands.)
Subsequently we inquired, Filtrete replied that its MPR filters capture more of the very small particles (0.iii to 1 micron) than equivalent MERV-rated filters when tested to ASHRAE 52.2 protocol, and shared a test summary that backs this up; on the larger particles (one to 10 or more microns), MERV and MPR performance was near identical. Filtrete said MPR 1900 is equivalent to MERV xiii, MPR 1500 to MERV 12, and MPR k to MERV 11.
Home Depot shared a basic comparative chart but no test data or protocols; it equates FPR ix and 10 to MERV 12, FPR 7 and 8 to MERV 11, and FPR half dozen to MERV ten.
How to choose a filter past its MERV rating
To decide what filter we'd purchase, we needed a more than pragmatic caption of MERV, so we turned to Kathleen Owen, a research engineer specializing in air filtration. Owen almost literally wrote the book on MERV: In the 1990s she helped ascertain the American Society of Heating, Refrigeration, and Air-Conditioning Engineers's ASHRAE 52.ii standard that'due south used to set the ratings. She afterwards chaired the ASHRAE 52.2 commission, which regularly updates the standard to address changes in filter technology.
In a conversation well-nigh the most common filter levels for auction at retail, MERV one through 16, Owen said this range "gets you from filters that might grab a golf ball—I'm exaggerating a little bit—upward to filters that will take hold of almost everything." Owen added, "I like to tell people that each of those filters has a purpose."
• MERV i to 4 (and unrated): Filters like the MERV 4 Due east-Z Flow, MERV 2 Truthful Bluish, MERV 1 Filtrete Basic Cut-To-Fit, and the unrated Flemish region, are the cheapest (some nether $one apiece) and most basic MERV-rated filters. Their purpose is to keep particles larger than 10 microns—including pet pilus (but not dander), carpet fibers, and heavy dust—from bottleneck the heating/cooling coils and ducts in your HVAC arrangement. They accept little to no impact on fine particulates like pollen and smoke, then they will not practice much to ease respiratory issues. But even with their limitations, these filters aren't pointless. They prolong the life of your equipment and help keep it running efficiently in the heating and cooling seasons. "Remember of how important your screen door is in summertime when there's flies out," Owen said. If yous are reading this guide, you probably care likewise much about air quality to consider one of these filters, only if you're living (or vacationing) in a rental and don't want to invest much—especially if the existing filter is problematically one-time or dirty—replacing it with a MERV one to 4 filter would be a fine quick fix.
• MERV 5 to seven: Owen said filters in this range (similar this MERV 7 Nordic Pure) were created as an improvement on the basic MERV one to 4 filters and designed to besides filter out midsize particles (three to ten microns, which includes most pollen and mold spores) that could encourage mold growth on heating/cooling coils. These filters are non as widely sold as the lower and higher MERV-rated filters in hardware stores, but they can be found online hands. There's zippo incorrect with these types of filters; we merely didn't focus on them as much every bit nosotros did those in the viii to xiii range mostly considering this class, by comparison, commonly isn't any cheaper, doesn't perform quite as well, and often isn't as easy to find.
• MERV eight to 13: This is the category we'd recommend for people who care about indoor air quality, and in that location are many as good examples, such equally the Nordic Pure MERV x and MERV 12, the Honeywell FPR 9, and the Filtrete 1500. (For more than detail on these models, see the A perfectly expert HVAC filter and Two other filters that are also fine sections.) We focused on filters in the MERV viii to 13 range because they are good to excellent at removing fine particulates (as small equally 0.iii to iii.0 microns in bore, including fume and exhaust particles and bacteria), plus anything larger. This MERV range, Owen said, "covers most of the stuff that people are likely to breathe in unless they're really close to the source." The EPA says filters rated MERV 7 to 13 "are likely to be nearly equally effective as truthful HEPA filters at controlling well-nigh airborne indoor particles." The higher terminate of the range, MERV xi to 13, removes 20-plus to fifty-plus percent of the very smallest, 0.iii-to-1.0-micron particulates, and filters in this range are especially pop. An NIH literature review indicates that filters in this range can significantly reduce indoor fine-particulate pollution and convalesce some respiratory ailments.
• MERV 14 through sixteen: These are specialized filters that crave a purpose-built HVAC organization; they're widely used in hospitals and some commercial and industrial environments, just generally not in homes.
Then why doesn't everyone get a MERV 8 to xiii filter? Beyond their higher cost, in that location is too a business organization your equipment might not be able to handle them, according to engineers we interviewed from two of the major HVAC manufacturers: Jay Ayers of Trane and Doug Powell of Carrier. They (and Owen) all told us MERV filters in this range restrict airflow more than than low-MERV filters, as measured by the drop in air pressure level the filters create when installed. That can potentially strain your equipment.
Powell noted that, "Y'all have a fair amount invested in your HVAC system, and unless you know how much pressure drop you lot have in information technology and how much more information technology tin can handle, you could end upwardly shortening the life of your blower. And a blower's not cheap." Ayers said, "That'due south the danger of looking at 1-inch filters and trying to become higher-efficiency and exercise the job that's needed for allergies: You lot run the risk of really damaging your blower and your HVAC organization." (If yous are concerned about this, to be absolutely punctilious you can hire an HVAC firm to measure pressure drop in your system.i)
Against these warnings, however, is a mountain of possessor testimony that MERV 11, 12, and even 13 filters have worked just fine in their systems for years. As well, an often-cited comprehensive contained test of MERV eight to 13 filters' effects on HVAC airflow and energy consumption (a proxy for how hard the equipment is working) ended that even "if no accommodations are made for the greater pressure drop of loftier-MERV filters, air menstruum and free energy penalties are not likely to be astringent—at least, not until the filter is loaded with dirt."
We feel the manufacturers' concerns are a bit overcautious, in part because a recent innovation in air filters permits high MERV ratings (11 to 13) with low pressure driblet.2 So-called electret filters use a mat of fibers that are electrostatically charged. The accuse helps attract airborne particles (rather than but passively impeding them). As a issue, the mat tin be more porous, causing better airflow and a smaller pressure level drop. Withal, Owen emphasized, electrets become less efficient over time, often significantly and so. "Electret media will drop in efficiency upon apply, sometimes by as much as 50 percent," she said. "Basically what happens is the tiny particles—we're talking twoscore, 50 nanometers, which there are gazillions of in the air—will coat the charged fibers and keep them from attracting larger particles." That means regularly replacing electrets is absolutely key to maintaining good filtration, and virtually come with 60- or ninety-twenty-four hour period replacement schedules. If you run your organization year-round, that's potentially half dozen filters a year.
Given all this, we decided that if nosotros were ownership new filters today, nosotros'd look for an electret filter around the MERV 8 to 13 level with a low pressure drop that was both affordable and easy to find.
A perfectly good HVAC filter: Nordic Pure MERV 12
Nordic Pure's MERV 12 filters are not the but products that meet all our criteria, simply they are perfectly good examples, and they're commonly competitively priced and piece of cake to notice online. We similar that they're genuinely MERV-certified, considering different the proprietary ratings used by some bigger-name brands, the MERV criteria are publicly bachelor. Being rated MERV 12, the Nordic Pures will remove at least 35 percent of particles in the 0.3-to-one.0-micron range, which includes bacteria and smoke; at least 80 per centum of 1.0-to-3.0-micron particles, which include fine dust and soot; and at to the lowest degree ninety percent of larger pollen, dust, pet hair, and lint particles. Again, MERV stands for Minimum Efficiency Reporting Value, then this is the worst operation measured during 3rd-party testing to the ASHRAE 52.2 standard. And once more: the MERV test measures a single pass of polluted air through the filter. In your home, the air will continuously recirculate when your HVAC arrangement is, leading to cumulatively greater filtration with each trip through the return registers.
Nordic Pure filters are generally sold online, and the MERV 12s typically retail for a much lower price than competitors—about $40 for a six-pack of 16-by-25-by-1-inch filters, or about $vii each (with some competitors you'll pay nigh double that cost for MERV 11/12 or the equivalent). At the recommended iii-calendar month replacement bicycle, a Nordic Pure can save yous about $30 to $forty a year.
Nordic Pure reports the filter's pressure drib as 0.24 inch, which puts it a shade higher than the like, MERV 12–equivalent Filtrete 1500 at 0.22 inch. But nearly people seem to accept had no issues with the Nordic Pures straining their HVAC system—the six-pack has an overall score of iv.iii stars (out of 5) across more than two,800 reviews at Amazon at this writing (we should note that the reviews once received an A rating from Fakespot; as of May 2019 that rating was downgraded to a C). The Nordic Pure MERV 12 filters are bachelor in many sizes, then you should be able to notice 1 that fits your return vent opening.
Two other filters that should practice a fine job
If you tin can't observe Nordic Pure in your size, or if you prefer to buy and choice up a new filter in a store immediately, Honeywell's FPR 9 filters and Filtrete'due south MPR 1500 filters are like, and they're widely available at retail. (Home Depot stocks Honeywell; Lowe's and Ace stock Filtrete). These filters perform on a similar level equally the Nordic Pure MERV 12, they are well-reviewed by many owners, they come in a wide range of sizes, and the loftier likelihood that they're in stock at a nearby hardware store is a large reward if you need one ASAP.
We don't love that neither Honeywell or Filtrete is MERV-certified, but their proprietary ratings are reportedly equivalent to MERV xi or 12. We couldn't discover pressure-drop information on the Honeywell, so that'due south a possible business organisation. The Filtrete'south pressure drop is 0.22 inch, fractionally lower than the Nordic Pure MERV 12's at 0.24 inch. Data Filtrete shared with us indicates the the 1500 removed 54 percent of 0.three-to-one-micron particles in its own tests, versus a minimum of 35 percent for the MERV 12-certified Nordic Pure. On larger particles, the two filters performed very similarly.
A major reason nosotros'd wait for Nordic Pure as an selection first comes downward to price: Both the Honeywell and Filtrete options usually cost more than than twice the price of the Nordic Pure filters. As electret filters, all these models will lose effectiveness as they capture particles, and should be replaced at to the lowest degree every 3 months, per the manufacturers' recommendation. But homes with certain challenging conditions—if you fume, oftentimes apply candles or fireplaces, or have pets—will significantly reduce that lifespan.3
Owen too offered a elementary way to judge if it'south time for a bandy: "If yous can become to your filter easily, one simple thing you can do is just go take a look. If you tin't run across the filter media anymore, information technology's been in there also long. Change it!"
How ofttimes should I supersede my filters during wildfire smoke events?
During a wildfire, you'll need to change your filters more oftentimes than yous would under normal air weather condition, and there are a few indicators that tin can help y'all know when it's time to supervene upon one.
We asked Kathleen Owen, the filtration practiced we spoke with for this guide, for her advice. She replied in an email: "If I lived about the wildfires and didn't find the price prohibitive, I'd probably modify a iii-month filter every month during the season. Or perchance afterwards each major consequence— say if a fire gets close plenty to be a large deal (rather than simply you know near it from the news)."
Owen also noted that wildfire smoke is a circuitous mixture, incorporating both physical smoke particles (which filters trap permanently) and water vapor and volatile organic compounds (gases), which are not trapped—and the latter of which create the smoky scent. "The wet particles or ones with gases adsorbed on them can exist collected, then give off the evil-smelling stuff the next time the fan comes on," she wrote. "So, i recommendation is that if folks feel like the air breathes easier or smells OK with the HVAC on but are gagging in the first infinitesimal or 2 the HVAC is on again, changing the filter could assistance."
There are also visual cues you can look for when judging whether to replace your furnace filter, Owen wrote. Bottleneck increases the pressure differential between the intake and outflow sides, and this can cause the filter's pleats to flatten out or the frame of the filter to buckle. Both are evidence that the smoky air is finding a path effectually the clogged filter rather than through it, and that it'southward fourth dimension to install a new one.
In addition to obvious steps like keeping windows and doors closed, Owen also advised shutting off bathroom fans and range hoods, both of which vent direct to the outside and, as a result, draw an equal volume of smoky outdoor air in through window frames and other leaky spots.
Owen added that she'd also consider calculation a portable air purifier with a VOC filter. All our purifier picks have them, and though in our tests against an farthermost load of ethanol vapors we found about of them ineffective, anecdotally we can say that they seem to perform well under fairly heavy smoke atmospheric condition. Both in guide author Tim Heffernan'due south apartment and in our New York test space, later on running our top picks for a few hours, there was trivial olfactory evidence that hundreds of matches had been burned nearby.
Finally, Owen noted that the American Society of Heating, Refrigeration, and Air-Workout Engineers (ASHRAE) has begun working on building-filtration guidelines specific to wildfire weather. We'll be post-obit upwards on this as information technology develops. For more on this topic, please come across our reporting on how to clean wildfire smoke from your habitation.
Footnotes
Source: https://www.nytimes.com/wirecutter/reviews/furnace-and-air-conditioner-filters-we-would-buy/
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