AC Infinity CLOUDLINE PRO S4, Quiet 4” Inline Duct Fan with Speed Controller – EC Motor Ventilation Exhaust Fan for Heating Cooling Booster, Grow Tents, Hydroponics

This is my third, and likely last, exhaust fan I've bought for a project. I wanted an exhaust system for our cat's litter box cabinet so that it would create a small amount of negative pressure and pull the bad odors outside. This fan is absolutely perfect in every possible way and has far exceeded my expectations. I arrived at this fan, after purchasing two others that were just too loud, as the noise seemed to bother the cat. I installed 2" PVC in the wall behind where the cabinet is, because I needed something small enough to fit. I then had a 90 degree elbow coming out of the wall, through a cover plate and then going into the back of the cabinet. In the attic, I installed a 2" to 4" duct adapter onto the 2" pipe, ran 25' of flex duct to this fan, and then another 16' run of duct to the roof vent. While the first two fans where very noisy, even at the lowest speeds, this one is virtually silent. I'm running it on level 2 and cannot hear anything inside the cabinet or in the house. Since I'm restricting the intake to only 2", anything above level 2 would likely just be a waste of power. This setup is working perfectly and creates more than enough exhaust to do the job and it does it in silence. The prior fans moved the air ok but had a really annoying hum that could be heard through the ductwork and also inside the house through the insulated ceiling. I hear nothing with this one. In addition to the above, the fan is rock solid and came with EVERYTHING one could possibly need to install it, including hose clamps. It's almost overkill but shows attention to detail. It also came with a very nice instruction book (yes, it's a substantial book) with detailed instructions on every aspect of installation and operation. The speed controller is very nice and easy to use. I just set it to my desired level and forget it. It will remember its current setting and resume after a power outage. This fan cost a bit more but is absolutely worth every penny paid. The difference in quality and quietness cannot be matched. I could not be happier, cat is happy, and we have an odor-free home.

This review is for the 4" version of the AC Infinity CLOUDLINE PRO, also known as the S4. My son had received a Falcon A1 Laser Engraver from his wife for Christmas and I offered to create a custom exhaust setup for it. They have a young child and what I had read about the possible toxicity of laser engraving fumes (specifically for leather cutting and engraving) motivated me to get the fumes completely out of their house and garage. After a few hours of research, I zeroed in on this CLOUDLINE PRO S4 for the task, as well as some 4" flexible duct and a silicone elbow/reducer (4" to 3", also found on Amazon). I was not disappointed with the results! See my two photos. I'm very methodical and careful, so it took me a few hours to complete the system, but most of that time was spent sawing through the garage drywall and configuring the termination of the duct at the roof's soffit. My observations: The inline fan is fairly big, but lightweight and is very easy to secure to the wall with the included mounting bracket. It's very quiet! The ten-speed variable control will take it from too quiet to hear, up to a whisper, and finally to a slight swooshing sound at full speed. I was impressed with the air volume it moved. I could definitely feel the air coming from the outlet outside. It reminded me of the volume of air a clothes dryer would produce. Sure enough, with a rating of 205 cfm (likely measured without ductwork), this fan compares to the average clothes dryer exhaust of 150 - 200 cfm. A bonus for the setup I installed is that garages are very leaky and exhausting this much air will bring a similar amount of outside air as "makeup air" and will create a cooling effect for the garage when it's hotter inside than outside. Everything I read online indicated that AC Infinity made good quality inline fans and I got the same impression working with it. Even the packaging and "presentation" upon opening it was far nicer than I had expected. I would definitely buy this brand of inline fan again the next time I need this type of ventilation.

I purchased the AC Infinity CLOUDLINE PRO S6, 6” Inline Duct Fan with Speed Controller to help keep my miner room cool, and it has exceeded expectations. The EC motor is both powerful and efficient, and what surprised me most is just how quiet it runs, even at higher speeds. Installation was straightforward, and the included speed controller makes it easy to adjust airflow as needed. Running multiple miners can heat up a room quickly, but this fan has made a huge difference — it keeps temps under control without adding a lot of noise or power draw. The build quality feels premium, and I can tell it’s designed to run continuously without issues. ✅ Pros: Very quiet operation, even at high speeds Strong airflow to keep miner room temperatures down Speed controller included for precise adjustment Efficient EC motor saves power over time Solid build quality, designed for 24/7 use ❌ Cons: Higher upfront cost compared to budget inline fans Speed controller cable could be a little longer 💡 Tips: Use insulated ducting to further reduce noise. Mount the fan with vibration-dampening straps for an even quieter setup. Pair it with a temperature or humidity controller for automatic adjustments. Clean the fan and ducts periodically to maintain peak airflow. Bottom Line: The CLOUDLINE PRO S6 is a top-tier ventilation fan that’s perfect for high-demand environments like mining rooms, hydroponics, or grow tents. It’s quiet, efficient, and powerful — exactly what you need for reliable cooling in a 24/7 setup.

I bought this fan to use with my Xtool laser machine. I am extremely excited about how well it works. It was not very difficult for us to install it in my basement and vent it out through a window. It is super easy to use. It is not as loud and the air purifier I was using. I would recommend this fan over and over again. The way it is helping my laser not only function better but keep fumes and smoke out of my room is amazing for the price. This is a great value. It seems to more than powerful enough and is sturdy and looks well built.

I'm very impressed and pleased with this 6" booster fan from AC Infinity. The user reviews were very helpful in my decision to purchase this blower. Especially the most-recent reviews tend to give a better picture of the item's performance. NO REGRETS! It was very fast shipping in a very well packaged box!!! You can tell when a manufacturer takes pride in their products just in the unboxing. Everything was premium quality! Specifically, the blower design is exceptionally well-designed and manufactured. The user manual was very good. Do read the manual first! This duct booster/fan can be mounted virtually anywhere in a number of flexible ways. In my case, the blower had to mounted between rigid 6" steel duct pipes. You might opt for the ~ 3" rubber adapter sleeves. I didn't and wish I had. But I was bent on getting the unit installed with what materials I had on hand. Not cobbled though! Anyway, if you must install the unit between two fixed pipes, first remove the blower proper from the main mounting bracket which incorporates the two IN/OUT adapter flares. Just loosen the two main banjo band clamps. You almost have to turn the screws all the way out before the bands can be pulled away. With the motor assembly removed, you can then mount the bracket sub-assembly to the ducts and secure that part of the set-up. Ingenious design that makes the rest of the assembly a "breeze", pun intended! Regarding the noise: I worked 35 years in noise & vibration control. There's no way this unit can be only 32 dB at typical or standard measurement locations. It must be rated such on the lowest speed. That said, the thing is still adequately quiet even at half-speed. And my basement bathroom is now toasty warm. Btw, I have this booster wired to come on only when the house HV blower comes on. It's nice that the digital blower control doesn't lose its setting. Everything on this huffer is top-notch and very well engineered.

This is an excellent quality fan in many ways, and is very quiet on the lowest 2 settings, and tolerable noise level on the 3d setting, but above that it gets intolerable for me. That's OK for my use, because I don't need to go above the 3d speed setting, which I'm told is about 130 CFM, but if you need more CFM, you may be better off using one of the larger versions to keep the noise level down at higher CFM. I do recommend staying with this Cloudline series of fans, because I don't think you will find anything else as quiet for any given CFM and pressure. I can't bypass the opportunity to scold the designers or product-design-decision makers for the stupid 1-button control concept that is all too common with many products these days. I mean if they just would realize how much more they would make by selling many more with the proper user-oriented controls, instead of trying to save a few pennies by using only 1 button, which forces the user to push the button 8 times to turn the speed down 1 tick, and to hold the button down to turn it on or off. To the product-design-decision makers: try to imagine what percentage more you might sell if you put the proper controls in to make the customers love it, instead of being annoyed by it, and then calculate how much more total profit might be made with that percentage increase is sales, and then see how that makes the tiny amount saved by 1-button irrelevant. Bottom line is to design for the user, not the ease of making it. I am very experienced in fans for ventilation, and so I didn't expect it to be quiet at the higher speeds, and I am very pleased with the quietness and good air flow at the lowest 3 settings. It performs very well for my purpose, which is home intake fresh air ventilation connected to a filter box. Even the lowest 2 settings move plenty of air to keep my 1000 square-foot home constantly supplied with fresh air, and in the summer, at night I use the 3d setting to bring in a little more cool air to help cool the house down. Blowing in filtered air is far superior to using an exhaust fan, because if you use an exhaust fan, then you suck air in through whatever dirty little cracks and openings might exist around your home, like under doors, so you get dirty air with an exhaust fan. Fantech makes a nice inline filter box, which can be used with this fan to bring in clean filtered air; mount the fan after the filter box to draw from the filter box and blow directly into the home. This ventilation method can be combined with an exhaust fan located in another part of the home, usually the bathroom, but just make sure the fresh air intake is equal-to or higher-than the flow of the exhaust fan to avoid sucking in dirty air through cracks.

I have to admit, when I was shopping for a power fan to vent my xTool P2 laser engraver, I was a little worried about power (would this fan give me enough?) and loudness levels (would it be too loud?) and I have to say, it's perfect on all accounts. My system is probably just as complex as you'd guess: xTool P2 Laser, connected to a xTool filtration system, and then vented outside. That's three ducts (printer to filter, filter to fan, fan to outside) at 4", and the P2 itself is natively 3", but I bought an adapter on-line to make it 4". So overall, the fan works great, like wow! You can still hear it - it's not super quiet, but it's also not annoying. It's more of a louder "whoosh" than an annoying whine, if that makes any sense? And that's me running this fan at full-power, which is basically where I'm going to keep it at. It's possible that your needs won't be 100% all the time, and it is absolutely quieter at the slower speeds. The duct connections are perfect, and the 6" to 4" adapters I purchased here on Amazon were absolutely flawless and leak-free. As someone who buys a lot of high-end computer components, one of the things I really appreciated about all of the AC Infinity products (three ducts and this fan) is that it's well packaged, with a lot of accessories. It's almost like opening an iPhone, if iPhones came in dark packaging. It's also clear what this fan was designed for, as it came with a "how to grow hemp" manual, which made me laugh. There's a nice YouTube video on-line that explains how to set this all up specifically with the P2 (with details on the 4" to 6" leak-free custom adapters), and he tells you to get this model, and not the one that has all the bells and whistles (Bluetooth, WiFi, garbage disposal, toothbrush). I'm glad I got this exact model (S6 PRO). The remote is cool, and comes with a nice LONG (9') cable so you can put this wherever you want. You press the button once to turn it on, and it remembers the last settings (1-10) if you hold the power button for four seconds to turn it off. It's pretty cool! I love the design, and the fact that you can remove the center blower, to install the bracket on the wall, and then put the blower back in. Solid build quality. Overall, I'm very happy with this blower fan, and would absolutely recommend it for hydroponics and exhaust systems.

The fan works great and has a wide range of performance that allows you to run this thing at any speed between silent and very loud. I use mine as part of a DIY ventilation system for an old apartment and it provides loads of air movement and static pressure. At full blast, I measured its power draw at 165 watts. The fan is notably very efficient and can still move a surprising amount of air at its lowest speeds with around just 5-10 watts of power usage. (Though you won't be ventilating a whole space at that level.) One thing to seriously note though: This fan can be a real safety hazard if not used correctly. It should really have some feature to kill the power easier since at full blast this fan will happily consume any nearby debris and probably result in injury if you were to get your hand in it. There is no built in grill or safety screen. The controller allows for the selection of 10 speeds, but requires you to loop through to the highest speed before it will shut off. Additionally, when you remove the controller by disconnection, the fan defaults to FULL power. I had an incident where the fan swallowed a bag of small screws and I had to hastily chase down the power plug in order to shut it off. I guess as a testament to its durability though the fan didn't seem to suffer any damage. I have since included a shutoff switch in-line with the power cord.