Crawlspace Vent Closes Automatically
- Paul Cummins
- Nov 12, 2015
- 1 min read
Updated: Sep 22, 2019
It responds to temperature based on different expansion rates of two metals fused together and opens automatically in the summer and closes in the winter without motors or electricity! The general rule is to have one square foot of venting for every 150 square feet of floor space. Click on image for link!