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

Great filter box. Built with good materials. Hinges are smooth and the latch is solid and looks and works great. I used this for my fresh air intake with a motorized damper for my A/C system. The inlet and outlet flanges were true to size and the door sealed very well with no leakage. It was easy to install and remove the included filter. This is heavy gauge metal and makes the box have some weight to it, so be prepared to have a way to mount or hang it. It's easy to tell this is a good product. The shipping box and packing were really nice....I hated to throw it away. You get quality with this box, it's worth the money, which is hard to find these days.

Great product. It allows me to move all my ventilation outside the tent, I use it as my pre filter and have the fan mounted directly to the carbon filter, giving far more room inside.

We used this 6" model for a fresh make up air for our house. Reading the review we realized people were upset that AC Infinity doesn't sell replacement air filters and those readily available filters at the big box store won't fit. If you are searching for a replacement then buy the Nordic Pure 12x20x1. Amazon sells this brand of filter as well. The actual measurements for this filter is: 11.5 x 19.5 x 0.75 inches. Although this air filter is about 0.25-.05 in short on the length and width, it still fit the air box and the seal is still in tact. See pictures for a visual illustration and reference my finger. As for the air box itself, this is a well constructed and high quality air inbox. This is expensive but I believe the quality and craftsmanship justified the price. I hope this review helps.

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!!

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.)

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.

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.

This thing is pretty solid, doesn't feel cheap. Remember to use 11.5 x 19.5 x .75 as a replacements. Its light enough to rest on top of a cheap 2x2 tent, maybe inside with proper port placement but for sure on TOP of it. First week this is catching little stuff that finds a way around the outside intake port. Second week I noticed a spider web on the filter side but not after, way better than finding webs in my grow and thinking I have spider mites. So after two weeks I don't think twice about buying this on a budget, its now a requirement to me like a carbon filter, it creates a peace of mind.