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

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 liked the features of this fan, including the speed control. It's a superior design because it has rotor and stator blades inside the housing. This type of fan is quieter more efficient than a simple fan blade design. The housing on either end can be split from the center motorized fan module by removing a clamp. This allows for cleaning the fan or swapping out a bad motor. This design simplifies a booster fan repair because once duct joints are assembled, especially in an HVAC system, they are difficult take them apart. Just remember when you are disassembling the body from the motorized section, DO NOT loosen the clamps all the way. Leave about 1/4 in of thread exposed below the nut. Even though the clamp isn't disassembled it is loose enough to take the fan apart. It feels sort of like the pop you feel when changing a bicycle tire and you push the bead of the tire over the rim.My application for this Inline Duct Fan was for HVAC ducts. Two legs of my system were fairly long and ducts were undersized. Installation was fairly simple. The set of steel duct clamps provided in the kit came in handy. I added mastic tape around the joint and activated the adhesive with hand pressure. Once attached, it's hard to take apart so I took my time to make a good seal and a mechanically strong joint. I needed to suspend my fan, so think about the mounting method before you get started. You could also use the bracket attached to the housing.I powered the fan with a relay circuit that energizes the booster fan only when the main HVAC unit comes on. I watched a YouTube video of someone else solving this requirement. I bought the relay on Amazon: RIBU1C Pilot Relay. After I finished the electrical work, I used the fan unit's 8 speed settings to adjust airflow and balance the HVAC system. I balanced the HVAC airflow by varying the speed on the fans. I have installed fans on two long duct runs. At fan speed 8 (max), the unit gets noticeably noisy, but it's also pushing a lot of air. You might not need top speed. In my system, setting the fan speed at 2 or 3 balances the airflow. At this setting, the fan is very quiet and still pushes a lot of air. Airflow adjustments can be made with the speed controller. The rooms connected to the system are now much more comfortable, summer and winter.

**Update**We leave our HVAC blower on 24/7 to keep air moving around the house. This fan here has been running 24/7 ever since it was turned on. It has never given any problems at all and still runs perfect. Zero complaints. I am actually thinking about purchasing another unit for the other section of the house now.I would buy 3 or 4 more but it would get expensive.We have a longer house with higher ceilings. The north side of the house was always about 5 to 8 degrees different. I purchased this and installed it on a long run to help push air. It pushes a lot of air! We only have it set about half way because it will blow the curtains all over the place. I wouldn't really call this quiet if you will be around the unit when its running on the top speed. You would find yourself talking over it a lot.Now the house seems to be equal temperature which is what I was going for.Installation was pretty simple. I cut out a section of 8" pipe and measured how much the fan body would use. I believe this model for me it came to about 9". I cut 9" off and reinstalled the end coming from the HVAC ducting and then mounted the fan body up, installed the guts and then finished by reconnecting the outlet ducting. I don't notice ANY vibration but I did mount the body with 4 screws tightly to the framing studs of the walls. The unit is down in the basement and nobody hears it running unless you are over by the air vents. Even then you don't hear the unit, you just hear moving air.Hopefully this thing lasts years. I am running it 24/7 like I do with our HVAC blower.