I'm building a portable cold frame; it's a 2x2 frame about 1.5 feet high, 4 feet long, and 3 feet deep. Sides and top will be covered with double thic k polycarbonate sheeting left over from building the greenhouse a few years back. My wife's idea is to put it out in the garden and start some seeds u nder it to get a jump on the growing season. Garden places sell things like this but want a fortune for them.
The problem is that on a very sunny day, it can get hot enough inside there to cook and kill the growing vegetables. I can put in a small, manually op erated vent, but would like to have something automatic, that opens when it gets too hot and closes when it gets cold again. I've googled around but c an't find what I need. I'm looking for something about 2 inches square that I can mount though a wall of the construction.
The people on this group have such a wide range of experience that it's pos sible that someone can give me a link to these devices, if they exist. Than ks for any help you can give.
Paul