Witten Automatic Vent B-EBLACK(MB) "Energy-Saver" Foundation Auto Vent 8" X 16"- Black

I bought three. Before installing, I tested them in my freezer. They are supposed to be fully closed at 35 degrees, so a freezer at zero degrees will more than do the job. You must stand them perfectly upright in the freezer - the same orientation as when they're installed, otherwise even a good one won't work properly. Apparently, the louvers are somewhat gravity assisted. After 30 minutes in the freezer, one of the three was still wide open. I exercised the louvers and found that the mechanism was sticking (hence, 4 stars). After working on it a bit, I found a rough spot on the bimetallic spring and fixed it. Then I took all three out of the freezer and sat them upright in front of a floor fan - the temperature was roughly 80-85 degrees (they are supposed to be fully open at 75). All three opened okay.Installation orientation is critical. Look for the word "TOP" molded into the plastic. The four screws are 3/16" hex-head capscrews. Tightening them with an L-shaped hex wrench is a lengthy process. Fortunately I had a 3/16" hex to 1/4" socket drive adapter and a 1/4" drive universal joint, so I tightened them with my cordless drill, which took less than 1 minute for each vent.Note that the temperature trip-point is adjustable, although I didn't need to do so. There is a nylon screw on the end of the vent which twists the bimetallic spring mount, the same way as old spring-type thermostats worked.

These vents look good. I cannot comment on their performance, as I haven't installed them yet. I ordered one and then three more.

Placed these all around my house with a crawl space. Fairly easy to install and seem to open and close as expected, so ordered more for another house.

Installed 12 of these on a home with a ground water problem under the joist floor with the addition of fans directly behind four of these. I tested one before installation by placing in my freezer and it did indeed close!I was concerned the fans would cause chatter on the louvers but the did not make any additional noise.

When I compare it to my HD old ones that were installed in 1990, they are basically the same. Over time the bolts corrode and rust so you cannot adjust them and they are hard to remove, This time I purchased stainless steel replacements which hopefully won't rust. Eventually the screen gets holes in it from various creatures trying to get in the crawlspace. Another reviewer suggested adding a finer mesh screen behind the one provided and I did that too. All eight of mine passed the freezer test but when winter arrives will be the real test. If I have to pull them out and tape them closed it's not a big deal since I may decide to add Styrofoam for insulation anyway.

I currently have the auto vents on my house now and was replacing one. Trying to install this one has been difficult. The screws are very difficult to tighten enough to secure into place. My guess is the holes for the screws are slightly to small. I agree with other reviews I will buy these locally where I can see the quality and ease first hand before purchasing.

Easy to work with

works great