AC Infinity CLOUDLINE S8 PRO - 8" Quiet Inline Duct Fan with 10-Speed EC Motor & Controller | Ventilation Exhaust System for Grow Tents, Hydroponics, HVAC Heating & Cooling | Perfect for Home Greenhouses, Indoor Gardening & Air Circulation

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.