Tjernlund V1D UnderAire Crawlspace Ventilator Fan Moisture Mold Reducing, 110 CFM

Used in crawl space. Installed below patio, has slight hum if you are listening for it, but we don’t even notice it. Been installed 4 months with no problems, runs continuously, we do not use timed feature.

Very well made and effective. It mounts easily and discretely below the house and you can basically set it and forget it. I work in water damage repair and ventilation under a house is key. This low power constant negative is perfect for setting up a gentle cross draft. I mounted this with some rubber grommets over the screws and some foam weatherstripping around the edges to reduce vibration /sound. Worked perfect and gives it an airtight seal to maintain negative draw in the crawl space.

Love it. Installed fan in a space under my front steps with the gas meter, electric meter, and oil tank. Floor is part of the (brick) house slab. Had always been higher humidity than the rest of the living space or outside. Now it tracks outside humidity. Fan is 110 CFM so it makes a little noise. Not a problem as this space is closed off. I did run a bead of caulk around the plate before installing (probably not really needed). Make sure it's installed tightly so it does not rattle. I like the long slots for mounting; makes it easy to find a spot to attach each corner. Had to run a short conduit and put in a (GFCI) outlet as the cord is only 6' long.

My house outside of Sacramento, CA is about 80' long by 50' deep, built on a slope that goes downhill in the back of the house - so I have a 'daylight' basement. The back 15' of the basement is finished living space, the middle 6' is a concrete walkway with shelves on either side for storage and the front 25-30' is dirt that starts with a retaining wall about 3' tall and slopes up a few few feet, so the headroom above the dirt at the front of the house is about 3'. When it rains, the dirt gets moist - this has led to slightly dank smells in the lower part of the house so I bought this fan to try to eliminate that. I mounted the fan in an under-house vent in the 'dirt section' and the one fan has made a big difference, although I think the calculations they suggest you perform say that I should have more. The smell is gone. Even better is that we used to find earwigs and other small multi-legged creatures in the living quarters - usually dead, but not always. We would get several a week, but once the fan was installed it's down to one every couple of months - no longer a factor. The fan is not too noisy, but our master bedroom and bathroom are immediately above the vent in which I installed the fan - and I could hear it at night (I'm a light sleeper). Also - the fan has a humidity sensor that turns it on if the basement humidity exceeds what you've set the sensor to (suggested somewhere in the 50-70% range). In Sacramento the daytime humidity could be 30% (at least in the summer) and the nighttime humidity could zoom up to 90%. It didn't make a lot of sense to me to be exchange basement 70% humid air for outside 90% humid air - although perhaps there are some benefits to fresh air regardless of the humidity. In any case, I bought a simple timer to allow the fan to run only from 9AM to 6PM and that has worked well. I may cut it down to shorter times if I get around to it.

I’ve only had this installed for a couple of days but man this thing moves some air for it being one fan! You can see in my video how much air it moves (until I got hit by a bug LOL). I would definitely like to see how much air the dual fan one moves! I got this to help move air out of my crawl space as there was tons of water dripping from my hvac ducts. This paired with sealing all other vents but one and installing a dehumidifier is keeping everything in my 1500 sq ft crawl space below 55% rh!

I had a mildew odor coming from under my breezeway that connects the house to the garage. The room is 14' x 17' and has a crawl space underneath about 3 feet deep. This space was totally enclosed by the builder. I had to cut a 2' hole in my foundation to gain access. I then mounted the fan in the opening allowing for the air to be circulated from the space and the mildew odor disappeared in less than a week. This product has performed wonderfully. I simply set the humidity control to the desired level and I was done with it. The sound level is so minimal unless your standing right beside it you don't even know it's on. Would highly recommend to anyone.

The Tjemlund UnderAire Crawl Space Ventlator is very easy to install and very quiet, but it moves quite a bit of air for its size. It has a sturdy build and can be trimmed to fit your vent if needed. I did not have to do any trimming at all, it fit my crawl space vents perfectly right out of the box. I was having a problem with the humidity in my crawl space until I installed the ventilator, now the humidity problem is gone. I also like the feature that you can set the humidity level to the % that you desire. Once the humidity gets below your setting the fan will cut off automatically, and then come back on if the humidity gets above the level that you set it on.

Works like a charm. Have pier-n-beam wood floor over dirt and needed a better way to pull in air through vents in underpinning. Set the unit around 40% humidity and it ran for days. It is now cutting off and on:) See other talking about noise. At first my install job on tin underpinning made the fan loud. Obtained some rubber bushing and isolated the unit from tin and can now barely hear the fan coming on. Only thing would I would change is; wish I had gotten the 2 fan unit for my sq footage.