AC InfinityCLOUDLINE PRO T4, Quiet 4” Inline Duct Fan with Temperature Humidity VPD Controller, WiFi Integrated App Control - Ventilation Exhaust Fan for Heating Cooling, Grow Tents, Hydroponics

I purchased this fan to exhaust warm air from a home theater equipment rack. With all the equipment turned on, the temperature in the rack quickly climbs to over 90 degrees. The equipment rack is recessed into a closet under a set of stairs, so goal was to activate the fan to pull warm air out as soon as the temperature rose to 80 degrees at the top of the rack. With the controller, it can be set to automatically and progressively increase fan speed after the temperature hits the target. Every 2 degrees after the target the fan can increase speed by 1 step.PROs:> Very quiet at fan speed 1 and 2. At 10, this fan pushes a lot of air.> Controller allows multiple control options - I just needed the high temperature option> Easy to install with the mounting plate - I got this mounted and installed in under 30 minutes.> Fan direction can easily be changed. The fan module just pulls out and you can change airflow without uninstalling - this is great to test whether pushing cold air in vs. pulling warm air out works better for your application.> Nice long temp/humidity probe and cable let me place the sensor exactly where I needed it.> Ability to place the controller wherever you want it as well.> Works seamlessly with their matching 4-inch flexible ducting, and wall mount duct grille.> Comes with two duct clamps> High quality construction -- strong mounting bracket, and thick plastic casing.CONS:> At speeds between 3 to 10 you definitely know it is running, though it is probably quieter than other fans.> I have this mounted to a wood support. At high fan speeds the motor vibration does reverberate through the wood supports - so need to play with how to isolate the fan if noise is important.> Controller settings are very complex given what you would typically want to do. To set the fan to turn on at 80 degrees and increment speed in steps as temps rise took a bunch of menu hopping and instruction manual reading -- not intuitive. In contrast this was a very simple setup on their AIRCOM fans.> Don't like the fact that in AUTO mode, multiple sensors can affect whether the fan turns on... Took a couple days to dial it in. High temp, low temp, high humidity, low humidity... hard to predict when the fan will turn on... I get this is geared for agricultural use, but setup is more complex than it needed to be.

I am writing this review for two reasons. The first reason is the Cloudline T4 fan unit itself, and AC Infinity's awesome customer service. The second reason is the title of the review. I am not using this in a grow room, but in an encapsulated crawl space as an exhaust fan.This fan is outstanding. It was easy to install and setup. For my use, I just have it strapped to a short cinder block and sitting on the floor of my crawl space. I have a Vivosun duct cover over the intake, as the intake is not connected to anything, and I didn't need a carbon filter for my application. I then have the AC Infinity 8' ducting connected to the hard duct that exhausts to the outside.My Fantech FR-100 was pulling way too much air, causing too much negative pressure in my townhome, and causing too much noise, mainly from bad mounting and thus vibration noise. The FR-100 was literally shoved into the hard duct, sheet metal screwed on, and then duct taped. Basically, just hanging there off of the hard metal duct.Anyway, I was wanting to know the CFM ratings per fan speed settings, and AC Infinity support was awesome, quick, friendly, and got me that information fast through their chat.The other issue I had, was the FR-100 was way too close to the inside floor intake vent, about 5' away. This made for uneven temps in my crawl space due to lack of air circulation. Air pulled into the crawl space and exhausted right out. With the T4 and ducting, I was able to place the fan much further from the intake making air circulation better and thus I now have more even crawl space temps.My crawl space is small, about 250 ft, and per code, only needs about 5 CFM. Setting 1 is about 45 CFM, and I am currently set on level 4, about 100 CFM. This in part due to the dust cover lowering the actual CFM and a backflow air valve on the intake from the house. I need to create enough pressure to make sure the valve opens and I was testing a few things. I will like lower the level to 2 eventually.Anyway, this Cloudline T4 fan, is truly whisper quiet. At 10, I am sure there is some noise, but in testing up close, from levels 1 to 6, you could barely hear it at 4 - 6.Overall, I am super impressed with the Cloudline T4 and its smart controller (which I will be upgrading to the WiFi model).