VIVOSUN 4 Inch Inline Duct Fan 100 CFM, HVAC Exhaust Ventilation Fan with Low Noise for Basements, Bathrooms, Kitchens and Attics, Silver

The VIVOSUN 4 Inch Inline Duct Fan with 100 CFM is an absolute must-have if you own a Keystone RV, especially models like the Avalanche 390DS. The lack of proper airflow in the HVAC system of these RVs, particularly in the rear bedroom, can make it unbearably hot. Keystone's quality control issues only add to the frustration. Installing this ventilation fan was straightforward, and the difference in airflow is night and day. The rear bedroom now receives proper air circulation, making it comfortable even on hot days. The fan operates quietly, which is a bonus, ensuring that it doesn't disturb your peace. For anyone dealing with similar HVAC issues in their Keystone RV, I highly recommend the VIVOSUN Inline Duct Fan. It's a reliable solution to prevent overheating and improve overall comfort. 🌬️🚐❄️

Works great. I’ve bought several of these. One failed after several months of 24/7 use, but the others have been running 24/7 for over a year with no issues.

Fan works but I undersized the ventilation needs. Should have gone with 6 inch.

I've used this every day for nearly 5 years as a fume extractor and it has never let me down. It moves a lot of air and does it reasonably quietly. I'm only here to buy another and forgot to leave a review.

At only 100 CFM, this fan isn't too bad. If 100 CFM is what you need. I was expecting more from the design, I guess. With adding an 8 gig video card to my recent computer build, the temps on my chip cooler sky rocket to around 104°F or 40°C on many games, from an average of around 82.4°F (28°C). Which isn't too bad really, but I want to add some filters for dust, & having 104°F pumping into the back room, makes it very hot on a summer day. So I searched around & found this, that I thought would be a solution. I figured it was better than a large Molex powered fan. What I wanted, was to remove the heat that the computer was pouring into the room, with a powerful fan & vent system. All of the air flow goes in the direction of the top vent, & out already. Now I want to pull it out of the room, to the window to the outside. The video card is loud enough on it's own (see review elsewhere), so adding filters to soften the sound, as well as a vent to pull the sound, should reduce it, along with the heat. I looked over Amazon & the net, & found this had the most "quiet sound". Quiet, being relative to the user, of course. Some reviews said it was loud (it is). As you can hear in the video, it is louder than the filtered & non filtered computer. Just to give you an idea. The computer has a twin active fan on the video card, A T-1 thermal tower for the CPU, a 120" side panel fan, & some case fans; on it's own it can be a little loud. Mostly it's the video card, as a simular tower build w/o the 8 gig video card can't be heard (see Black Ice Monster review). So, noise isn't winning any awards. The video is via my phone, not great, not bad. Gaming headset doesn't pick it up, as an FYI. The second & most important thing this Vivosun booster fan needs to do, is evacuate the heat from the computer, so that it doesn't enter the room. The third thing it needs to do (on this checklist), is keep the computer cool. Preferably below current temps, but with in an acceptable range, as long as it's evacuating the room. So far, it's doing #2 alright. Bottom line: With the computer filtered & shut; it will drop the temp about 1-2°C in about 2 minutes. With the side panel off, it will drop it 5°C in 1 minute. The mean running temp in spring: is 35°C (95°F) Under load 43°C (109°F) With the fan off the computer has reached 52°C (125°F) under load on a simple game (Little Nightmares), & the VivoSun brought it down to about 42°C in about 10 minutes. Outside it was around 82°F, the room about 75°F with a pole fan running. So it does alright, just not great. It runs helps at about 5°C on average, but it does evacuate the heat to the outdoors for the most part. I can't say if the 240 CFM fan will do any better as I'm afraid it will be much louder. It's not horrible, just not quiet It sounds like an A/C unit. Oh yeah, it has a tick now after intermittent use in three months. I don't run the vivo fan when just doing text or surfing, only when gaming or doing 3D stuff. Also, the power cord is plenty long great job !! I have it on a wireless remote so I just click & on.

Package came in this afternoon and before dinner time, I had it installed. I installed it on the back end of my galvanized dryer vent tube (it runs 28ft to the vent outside) and fired it up straight away since we were doing laundry today. Not only is this little thing a good deal but it is WAY more powerful than I thought. Within minutes, the moisture on the windows in our mudroom was disippating (and now completely dry) but, our laundry is DRYING EVEN FASTER! The fan is installed in our basement ceiling but, I can't hear it running, even went downstairs twice to make sure so, I would say it is pretty quiet. All in all, this is a good product at a decent price. Not sure how well it functions for different applications but, for how I used it, I'm very pleased!

Barely moves any air. This has a very limited use.

This product was in my bedroom (no explanation for its placement will be provided) and never woke me. While awake it is noticeable, but would be comparable to a box fan on high.