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

An excellent product, easily installed, and providing a very fine varmint barrier!

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.

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.

I bought two of these and feel they are overpriced, cheaply made plastic snap together construction. The design is "OK" but the actual build is flimsy. Of the two vents I bought, one came with no set screws so I was forced to find and repurpose old screws. Inside both units, the spring that opens and closes the sheet metal vents had fallen off, so I spent 30 minutes disassembling both units to reinstall the springs. I then put both units in my freezer at 0F degrees and they only partially closed. I have looked at pictures to make sure I reinstalled the springs correctly. The set screws they supply are slotted on the top for a flat-head screwdriver which is not the best for this application; they should supply Allen head screws. Overall, these vents are not good quality and if I could find better ones, I would pay more for them. I rarely give poor reviews but these are just facts about this product.

It was what I needed

It is a witten brand but not like the one that came from professional provider. It was installed but fits differently to skirting.

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.

Overall great value for the price and rare item that is hard to find in local stores.Important note for buyers - this vent is black, but I was able to paint it into various colors using color spray.Also to test automatic feature - put this vent in your freezer to see if it works before installing.Plastic and aluminum should last for years.