AC InfinityCLOUDLINE S8 PRO, Quiet 8” Inline Duct Fan with 10-Speed Controller, EC-Motor Ventilation Exhaust Fan for Heating Cooling Booster, Grow Tents, Hydroponics

I'm using this fan as part of a CR box air cleaner. It runs 24/7 and is a champ. The controller documentation could be a bit better but it's a great fan regardless.

Buy this fan and don't try and save a couple bucks buying some other cheaper crap. I bought 2 other fans from different companies trying to save money, both had good reviews on Amzn, both turned out to be complete garbage. So I finally bit the bullet and bought this one and I have no regrets! Its got great CFM and Static Pressure. AC Infinity has a company headquarters is in the US, their customer service is excellent and will answer any questions you have. BUY THIS!

I have been amazed with this product. And I have been wanting to write a detailed review to highlight the quality of this product, but also to highlight that HVAC booster fans can work despite the negativity found online from the HVAC industry.First of all the quality of these fans is amazing. Very high quality construction and for their size they are remarkably quiet. I am not sure how the manufacturer rates the sounds levels, but at their highest fans speeds they are quit noisy, but for an HVAC booster application you will only need the lower fan speeds which are very quiet. Since my fans are mounted in the attic, the only added noise I hear in the house is the additional air flow coming through the ceiling registry/vent. As for airflow rates, this fan has some ridiculous flow capacity. Literally the first time I fired up the fan with it sitting on my wood flooring, at speed 8 the fan started traveling across the floor like a swamp boat. Now I will mention that if used in an HVAC application, you will need to properly insulate the fan housing to prevent condensation from forming on the exterior of the fan housing. I also questioned what the current load was for these fans and the manufacturer was not able to provide that information, so I took my own current readings. Below are the current loads at each fan speed for the 8" model:1 - 0.08 amps2 - 0.10 amps3 - 0.18 amps4 - 0.30 amps5 - 0.48 amps6 - 0.75 amps7 - 1.12 amps8 - 1.52 ampsThe reason I needed to know the current load for these fans is that in my application I wanted the booster fans to run only when the central HVAC blower was on. To accomplish this I installed a dedicated outlet that is switches on by a Vortex Power Fans AC Current Switch (or current operated solid state relay). The problem is this current switch is limited to handling 2.5 amps. My original plan was to run a relay for each fan, but since I was operating the fans at speeds 1-3 only, I was able to combine the fans on a single current switch.So at the end of the day why did I need these fans? Well my HVAC is poorly laid out with the unit located at one end of the house, so our master bedroom at the other end of the house has a 50-ft duct run, where most of the house is on duct runs less than 20-ft. The air flow loss due to the long duct run caused an average temperate difference of 2.5 degrees, with spikes of 5-6 degrees during the late afternoon sun, as documented by my Ecobee themostat and additional temperature sensors. Since installing the 2 booster fans that route air to our master bedroom, we have completely reversed the temperature difference, so that now our master bedroom averages about 0.5 degrees cooler than the main thermostat. So a full 3 degree temperature swing and that is with both fans running on the lowest speed (1). The reality is, I could have easily gotten away with installing only 1 fan, as I ran a single fan for several days at speed 3, and that was enough to balance our bedroom alone.

I installed above my 42U home server cabinet (currently with 30U populated) to keep the equipment cooler. Before I just had a fan blowing onto the rack which kept it cool enough I didn’t need to worry about damaging equipment, but warm enough the fans were screaming (especially the 12x 1u servers and their power supplies). I added a 10x10 filtered intake and ducted into the A/C intake box with the fan inline. With the house temperature set to 75° And the fan on high, I read a temperature of 76.2° outside of the server cabinet, and a temperature of 77.0° at the intake vent directly above all of the equipment. I added some “plastic curtains” (like you’d see on a warehouse door) cut to length to meet with the top of the cabinet, which keeps the rack pretty well sealed off so air going to the vent must pass through the rack itself. I’ve also made sure to install rack blanks in any unpopulated slots. I can still fill in some small gaps (a couple of 1/2U spaces) which I know will help considerably still. Now the equipment is far quieter, and all systems are running considerably cooler.I ran the duct directly to the air return on the A/C unit because I do not want to create a vacuum in my house by venting directly into the attic as many people do with their equipment. The pressure difference will either cause air to be pulled back into the house from the attic (which is often 130°+ here in Vegas), or from outside (which is often 105°+ in the summer). This way it will continue to circulate the (slightly) warmer air throughout the house, which in turn will cause the A/C to kick on more often to maintain the temperature. It’s not perfect of course, but it’s better than creating one very hot spot in the house, or sucking much hotter air in through the attic/outside.As for noise, the fan is installed in the attic screwed directly to a rafter (no bungee cords or anything to dampen the noise/vibration). If the house is very quiet, I can hear a slight hum when I’m near that area. Slight enough I really have to pay attention and try to notice it. Slight enough I’m not even entirely sure I’m not just imagining it. This is with the fan on full speed also. Even turning it down a notch makes it considerably quieter. It’s definitely way quieter and a huge net positive from the db level decrease from my servers.Instillation could’ve been easier. The size of the fans duct was considerably smaller than the ducting itself, which made it tricky to get a good seal around it and fasten the flex duct down. Of course this was very much amplified by working in the cramped space in my attic. I’d like to see a more appropriately sized intake/outlet if they decide to redesign it, and the fact they didn’t spec it correctly is very odd considering the build quality seems to be good quality (as you’d expect given the price).

I've bought quite a few of these 8" duct fans. This one looks to be the best construction of any of them that I've had over the years. Hopefully it lives up to its impressive initial impression...

Was too big for my Glowforge so returned but very well made and I ordered a different size.