TjernlundV1D UnderAire Crawlspace Ventilator Fan Moisture Mold Reducing, 110 CFM

These are top quality units, galvanized metal housing, and is easy to operate and install. I would recommend buying a remote Acurite Model # 00611A3 temp/humidity sensor ($26.00 amazon). My crawlspace is at 50 degrees with 77% humidity currently mid-december (with winter covers installed outside) , these vents will try to automatically operate even though the outside themperature is 30 degrees or less. The Ventilator has a sensor and will not operate below 35 degrees. With my crawlspace currently at 50 degrees these fans will try to operate. I have added a line switch to the outlets to make sure they remain off during the winter. You could unplug them of course, but I do not want to crawl down there if I don't have to. Excellent product, these will eliminate the moisture problems in my crawlspace and keep the air moving. They also will help to remove radon gas if present.

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.

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.

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.

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.

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.

The unit was easy to install and runs quietly. However, the online description could have been clearer. I bought the fan to replace an exhaust fan in my crawl space that had ceased working. I wanted a fan to blow the humid air OUT of the crawl space like the old one did. This one blows air INWARD into the crawl space, the idea being that the moist air will then blow out through the regular foundation vents. That is fine I guess, but not what I wanted. I would not have bought this particular unit if I had known, but the online data did not state this fact.