TjernlundV4D UnderAire Moisture Reducing Crawlspace Ventilator Fan

you need to be a bit handy to install properly. install will vary depending on wood or block construction. so far my cellars smell problem is gone. will further review down the road on endurance of this product.

So thankful for this hardworking little fan. After an unfortunate sewage leak occurred in our crawl space, we had an awful smell in the house for weeks. Even after talking appropriate steps to deal with the leak and the spill, the humidity in the crawl space made the smell persist. The fan was the solution. We were able to install it in an existing vest from outside the house (it’s plugged in to a weather-proof outdoor outlet). Within 24 hours of installing it, the smell in the house was completely gone.This fan has a built-in humidistat, so you can adjust it to turn on automatically when the humidity in the crawl space reaches a certain level. It operates very quietly. Installation was simple and quick (be sure to measure your vent opening to ensure a good fit). Other reviews mentioned excellent longevity, so I’m hopeful about our unit. Highly recommended.

Relatively sturdy. I had gotten this to help with removing basement humidity. However, since I've gotten this appliance, my humidity doesn't get lower than 60%, which before installation was around 55%. The good news is that it's powerful enough that it has gotten rid of the stale basement air.

It’s a little noisy at full power but it’s in the basement and works really well.

We had our crawlspace encapsulated last year and they didn't install an exhaust fan. Pretty soon we started to get the "cat pee" smell in the house that a lot of people seem to experience, which is actually ammonia being released from the soil. I didn't want to pay to have them come back and install a fan (which they should have done originally, but I didn't know that at the time), so I bought the Tjernlund V2D to install myself.When I unboxed the fan it looked good and didn't feel cheap. I noticed that the frame was a little warped, but it easily flattened out when I screwed it in place, so this wasn't a big deal. Installation was pretty easy, but will vary depending on your situation. The vent opening I chose was larger than the fan, so I used some scrap plywood to make a frame. I secured the wood frame to the cinderblock with concrete screws and then secured the fan to the wood frame. I had to run a short extension cord to reach an outlet. Not ideal, but the fan has a very low amp draw.We have a dehumidifier in the crawlspace (part of the encapsulation) and I was only concerned with evacuating the ammonia, so I set the fan to always run and it's been running constantly for 8 months and still seems to be running like new. The fan evacuates enough air that we're no longer getting air leakage into the house and we haven't smelled ammonia in the house at all since installing the fan. Yay!!When it's running you can hear it outside within maybe 25 feet. Inside you can faintly hear it if you're standing within a couple feet of it, otherwise you'd probably never notice. Even outside the sound isn't obnoxious though. Basically sounds like two big PC fans, which is basically what I'd imagine they are.We had to stop the ammonia smell from getting into the house, but I didn't want a huge hassle installing a fan and I didn't want cheap junk that had to be replaced after a few months. Overall I'm extremely satisfied with the fan.

I was concerned by some reviewers that said the ventilator was too loud. I am very sensitive to noises, especially mechanical ones. The ventilator I received is not loud at all. It is audible in the crawlspace and for a few feet just outside the vent, but I wouldn't consider it loud even standing right next to it. I can't hear it inside the house, even standing directly over where it is mounted.To be cautious about sound and vibration, I used some weatherstripping between the ventilator and the block wall where it is mounted and also used rubber washers on the screws. I now believe none of that was necessary and noise would not have been an issue even without those precautions.I have no reason to doubt that the ventilator is moving its rated CFM of air, but it is certainly not producing a gale force wind. I haven't had it installed long enough to know if it will really impact the temperature or humidity level in my crawlspace.Update:I've now noticed that when the house is very quiet and I'm in the room directly above the ventilator, I can hear it faintly inside the house. Any water running or central heat/air running are much louder than the ventilator and drown it out, so I still don't consider noise to be much of an issue.As to effectiveness, the ventilator has not had much impact on the temperature or moisture level in the crawlspace so far. My crawlspace is large at about 8000 cubic feet and I believe the manufacturer guidelines recommend 3 of the ventilators for that much space. I've ordered a second ventilator and am hoping that two will have a bigger impact.Another Update:Having installed a second one of these ventilators and lived with it for a couple of weeks, I'm changing my rating from 5 stars to 4 stars.The second ventilator, though it doesn't really sound any louder than the first one, is more noticeable because the sound is penetrating the floor more. I can't hear it inside more than a few feet away, but sound is enough of an issue that I've put it on a timer so that the ventilator only runs at times I'm unlikely to be in the room above it.The bigger issue is that running both ventilators most of the time for a couple of weeks has had a negligible impact on moisture and humidity in the crawlspace. They are definitely circulating some air through the crawlspace - just not enough to make a huge difference.The ventilators seem well designed and well made. But, I'm unconvinced at this point that they are very helpful or very effective in controlling crawlspace dampness.Update August 29, 2012.Now that a good bit of time has gone by, I've reached the conclusion that outdoor summertime humidity in the Memphis area is high enough that no reasonable amount of ventilation will reduce crawlspace humidity much below 80%. Keep in mind that even if the outside air has lower relative humidity, you're bringing it into a crawlspace that is almost certainly substantially cooler. In doing so, you decrease the amount of moisture that the air is capable of holding and therefore increasing the relative humidity of the same air with the same absolute moisture content.I still like having the ventilators run to bring fresh air into the crawlspace, but they aren't practical in this area for reducing crawlspace humidity during the summer. Things may change in the winter when conditions reverse, bringing cooler and possibly less moist air in from outside to a warmer crawlspace.

Best purchase ever made works as described

Installed same unit over 5 years ago and finally crapped out this spring. It ran 24/7 during that time so held up great! Hopefully this one also lasts another 5+ years!