VIVOSUN Inline Booster Duct Fan 6” 240 CFM, HVAC Exhaust Ventilation Fan with Low Noise for Basements, Bathrooms, Kitchens, Attics, Grow Tents, Black

I use this to extract heat from a portable A/C unit.I needed a fan with metallic blades due to heat. The heat it is exposed to will warp plastic fan blades. I was worried about the fan motor’s exposure to heat as well.This fan (in my application) is exposed to 145 degree internal duct heat for hours at a time which is right at the end of the motor’s advertised tolerance.It has been working without issues for over two months in Florida weather. I run it for as long as 6 hours straight, as needed.I use this fan to extract exhaust heat from a portable 9000 BTU A/C unit in my garage. This unit may also have use in a hurricane aftermath scenario (as in cooling a tent erected inside the house for sleeping (powered by a gas generator located OUTSIDE), if the power is out for weeks.This fan is hard mounted to a plate which I fabricated which seals the window opening completely. It can be removed from the window in less than 30 seconds. It also locks the window to help avoid entry from outside.I insulated the original flex duct with commercial grade insulation material used for A/C ducts in attics.The portable A/C unit is connected to the insulated duct, and then to this fan assembly at the window plate on the other end. The straight 4 foot duct run has two 45° elbows... this fan creates a vacuum in the duct to draw the heat outside better than the A/C u it could before.These portable A/C units are completely useless unless you facilitate the extraction of the heated air they produce. The uninsulated plastic exhaust ductwork they come with simply transfers all the heat the create right back into the room before it gets outside. It’s so hot in fact, it melts and distorts the window mount that comes with the A/C unit, allowing the heated air to literally blow back into the space you are trying to cool! It would heat and cool the garage simultaneously. Incredibly stupid and costly.To remedy, I insulated the exhaust duct from the A/C unit all the way up the the fan (at the window plate) in order to keep the heat in the duct, and not let it radiate back into the garage airspace. This fan sucks the hot air out.The window/fan mounting plate is made of 3/8 finish grade plywood, and painted with a two part epoxy, as to be waterproof and look nice.The fan is mounted to the plywood with a metal ring I fabricated using rivets, and it seals with a gasket. Control of the fan is manual, via the same power strip that supplies the A/C unit. The sound level is lower than the A/C unit’s noise output.The result: My garage can now reach 78°, with a 50% humidity level on a July day like today. Without the AC, the garage is 85% humidity, and 95°F.

I don't care about plastic housings and I'm happy to wire my own switches where relevant, so for me and the applications for which I use fans (in this case, cooling inside my truck/paired with optional swamp cooler water flow), this is awesome bang for my buck. It's a bit loud but I don't care, that's to be expected when going for something with high airflow.I do wish I'd considered getting a couple of different sizes because this is actually more powerful than I need for its current use, but that's fine, sooner or later I'll move it and the attached swamp cooler setup I built to a different larger space and build a new smaller one for my truck. I'd much rather overengineer something than have it be insufficient (like my first pitiful swamp cooler attempt with computer case fans -- fun starter project to learn about wiring in series and wiring a three-prong switch, but totally inadequate for cooling the inside of a Ford Explorer!).So yeah, can't speak to how good this is for actual use in ducts, but as a cheap powerful basic fan for a DIYer doing something fan-related, it's a great buy and I'm thrilled I got it. The only way it could be more perfect would be if it had an on/off switch already integrated into the power cord, but that's not a big deal and of course it's not like it advertised/implied that it would have one. It's exactly what I expected, except more powerful. Everything about it seems solidly made and I anticipate it'll last a very long time. I'll most likely buy from this same manufacturer again in the future when I need fans of other sizes.

Installing this fan was super easy, as well as getting it powered up. At full speed this fan is quite noisy, but my main issue is that it vibrates A TON at full speed. I bought an external fan speed regulator switch so I could slow it down to eliminate the intense vibration. This helps with vibrations and noise level, but of course provides worse air flow. While the fan is very powerful at this price point, it would be nice if the fan blades were balanced.

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. 🌬️🚐❄️