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AC Infinity

AC Infinity Inline Filter Box 4" with High Efficacy Filter, Whole House HVAC Filtration Kit, Fits 4-Inch Inline Duct Fans for Fresh Air Intake and Ventilation

    • Based on 216 reviews
Condition: New
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Availability: In Stock.
Fulfilled by Amazon
Arrives Tuesday, May 21
Order within 1 hour and 13 minutes
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Style: 4-Inch


Size: 1 Count (Pack of 1)


Features

  • A duct filter box designed for use with inline fans to circulate fresh air and block dust and odors.
  • Built with 1mm thick cold-rolled steel and aluminum duct flanges, able to withstand extreme weather.
  • Slide lock door gives easy access to inner chamber while soft neoprene layer creates dust-free seal.
  • Includes a standard high efficacy filter that traps particles like dust, dirt, lint, and odor.
  • 23.46 x 8.42 x 11.73 | Fits 4 Inline Fans | 400 CFM Maximum | Accepts 12 x 20 x 1 Filters

Brand: AC Infinity


Material: Aluminum, Alloy Steel


Product Dimensions: 23.46"L x 8.42"W x 11.73"Th


MERV Rating: 13


Item Weight: 6.42 Kilograms


Brand Name: ‎AC Infinity


Model Info: ‎AC-AFB4


Item Weight: ‎14.12 pounds


Product Dimensions: ‎0.93 x 0.46 x 0.33 inches


Item model number: ‎AC-AFB4


Part Number: ‎AC-AFB


Material Type: ‎Aluminum, Alloy Steel


Batteries Included?: ‎No


Batteries Required?: ‎No


Date First Available: April 7, 2021


Frequently asked questions

If you place your order now, the estimated arrival date for this product is: Tuesday, May 21

Yes, absolutely! You may return this product for a full refund within 30 days of receiving it.

To initiate a return, please visit our Returns Center.

View our full returns policy here.

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Top Amazon Reviews

    • Awesome build quality on this beauty!
Style: 6-Inch Size: 1 Count (Pack of 1)
This box looks so good, it's almost a shame I have to mount it in a hidden area. It's solid. It's tough, and the finish is great. The box it was packaged in got heavily damaged in shipping, and the strength of the air handler itself is what saved it from damage. Only a few nicks to the powdercoat finish, no discernible dents, and no affect to the body or door. It latches solidly, seals competently, and comes with a pleated filter already included inside it (independently shrink-wrapped, of course) I also bought a pair of backdraft butterfly dampers (6" as well) from AC Infinity, and their build quality blew me away just as much. I'm really impressed with this company. Yeah, their stuff isn't the cheapest, but you really get what you pay for with these people. I'll be trying to use their products in future projects as often as possible. Highly recommended!! ... show more
Reviewed in the United States on March 24, 2024 by J. Street
    • Great Fresh Air System - Filter Out Wildfire Smoke
Style: 4-Inch Size: 1 Count (Pack of 1)
Review Image by MoonManPics MoonManPics
Review Image by MoonManPics MoonManPics
I live in an area plagued by wildfire smoke and every year gets worse. I live in a Valley so temperature inversions are common and many of my neighbors have wood buring stove and some even illegally burn thei household garbage. I have indoor air cleaners which keep my indoor air quality index (AQI) very low, 1 to 4. However, Carbon Dioxide (CO2) levels get very high, especially in the bedroom when it can reach as high a 1400 ppm in the morning. Anything above 1000 ppm can cause headaches, fatigue, and other health issues. I assembled the system pictured it consists of the following: * AC Infinity Inline Filter Box fitted with Filterbuy 12x20x1 MERV 13 rated filters * AC Infinity Cloudline Pro S4 Inline Duct Fan * AC Infinity Flexible 4-inch Aluminum 4 layer HD Flex Hose (25') * Broan-NuTine 465B 4" to 5" Duct Adaptor * Gulrear Portable AC Window Vent Kit 5" I assembled these components and it allows me to draw in air from the outside, filter it, and disperse into the room. The 25' hose allowed me to place the outlet just below the top of the ceiling where monitoring have indicated is the best location. I use the IQ Air Airvisual Pro N1 indoor air quality monitor in the bedroom to track the AQI Index and most importantly for this purpose, the CO2 level. Prior to installing this system my highest reading in the morning averaged 950 ppm. Now I average 650 ppm. My 24 hour/day monthly average went from 735 ppm to 588 ppm. I am very pleased with the performance of the system and achieved my goal of reducing CO2 levels when I am unable to open the windows due to unhealty outdoor air quality. The AC Infinity products are of excellent quality and the inline Duct Fan is very quiet. I leave set at the 5 (out of 10) power level and it is very quiet. The combination of my air cleaner and the AC Infinity fan makes a great white noise level for restful sleep. In the pictures you will see how I have hidden some of the components under a chair. You can also see the hose outlet hidden behind the flower vase on top of the armoire. Update: Condensation inside the filter box was a concern, but with outside temps since installing in mid-October ranging from 65° to 22° F we have had zero moisture build up inside the filter box. Dry as a bone. ... show more
Reviewed in the United States on December 3, 2023 by MoonManPics MoonManPics
    • Great inline air intake filter
Style: 4-Inch Size: 1 Count (Pack of 1)
After installing an ERV, I noticed the intake air is not sufficiently filtered and that caused PM 2.5 particle counts to go up in the house. This filter is a great solution and I placed it before the ERV to filter the intake air before it reaches the ERV. This has dramatically reduced PM 2.5 particle count back to normal range. It's easy to install and is very solid. It doesn't come with any means to mount the filter or hang it. It's also not insulated so it can condensate if outside air is much colder than inside. I was worried about the box but it was well packaged. Finding the right filter for the 4 in and 6 in version might be a problem, but I think the Home Depot HDX 12X20 MERV 13 filter should fit based on the size of the filter online. But I am using the provided filter at the moment. ... show more
Reviewed in the United States on November 9, 2023 by R. Lin
    • Beautifully made. The 8" fits standard 3M Filtrete filters, but the 6" does not.
Style: 6-Inch Size: 1 Count (Pack of 1)
Review Image by David David
Review Image by David David
REVIEW OF 6" (4 Star because Non-standard Filter Size) AC Infinity makes great products and this new 6" filter box is no exception. It is essentially identical to the Fantech FB6, except that the AC Infinity version: 1) takes 12x20x1" filters instead of 10x20x1" filters, 2) is black instead of tan, 3) has the lid flip up on hinges as opposed to pulling out using wing nuts, 4) doesn't have the pre-drilled 'hanging holes' that you have to tape over with the Fantech version, and 5) has metal duct connectors instead of plastic. Importantly, just like the Fantech FB6, the AC Infinity 6" filter box is NOT designed to accept just any 12x20x1" nominal-sized filter. It comes with an AC Infinity filter that measures 11 1/2" x 19 3/8" and fits into the metal filter rack inside the box. There is only around 1/16" of wiggle room between the filter and the metal rack. This means that this filter box will NOT fit 3M Filtrete 12x20x1" filters, which have actual measurements of 11 13/16" x 19 13/16". You're going to need to either buy AC Infinity replacement filters (if/when they're made available) or other filters with a 1/2" cut-in both length-wise and width-wise. I've unfortunately been through this before thanks to the Fantech FB6, and Dupont makes some 1/2" cut-in filters that you should be able to jam in (be careful, some Dupont filters have only 1/4" cut-ins). AC Infinity (and Fantech) are in a tough spot because they don't want to let air get around the filters, so it's tricky when there is no standard cut-in size among filter manufacturers. The AC Infinity filter it comes with appears to be well-made. The folds are rigid, instead of the flimsy filter the Fantech FB6 comes with. I didn't take the filter apart to confirm that the filter material had been diligently glued to the inside cardboard perimeter to avoid leakage. I'd recommend buying this AC Infinity over the Fantech FB6, if (1) you can spare the extra 2" width and (2) AC Infinity prices their replacement filters competitively (TBD). The extra 2" filter width (12" vs 10") on a 6" system will help control pressure drop, which goes parabolic around 150 CFMs in the Fantech. Also, the Fantech replacement filters are flimsy and overpriced at roughly $30, which is way above standard replacement filter prices (hence, jamming in the Dupont filters). It would get 5 stars if AC Infinity sold replacement filters at a reasonable price (so far, I haven't seen replacements for sale). REVIEW OF 8": Buy the 8" if you have the space. It fits 3M Filtrete 14x20x1" filters literally perfectly and will save you so much brain damage. This filter box is a big boy, but it's EPIC construction quality. Thank you AC Infinity for sticking to a standard filter size with this model! (BTW, keep mentioning 3M Filtrete filters because they're well-constructed, readily available, and provide a wide range of MERV/MPR options at various price points. The 3M MPR 1900 filter is the sweet spot of particle capture (MERV 13) and low pressure drop; because of the extensive pleating and material, this particular filter line actually has the lowest initial pressure drop out of all of the 3M filters, even much cheaper ones. Feel free to use a lower MERV/cheaper filter if you don't need that level of filtration.) ... show more
Reviewed in the United States on May 22, 2021 by David David

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