"yar> I stand corrected. Yes with right material the fan would attempt to pull the flap closed. So did you simply use a hole saw to create your holes? Maybe some aluminum flat bar stock, button head screws and some ultra fine rubber gasket material for your flaps. Does this all sound about right?"
Yes, that's exactly what worked out well for me. Good eye!
I'm really glad to be able to offer some information that's potentially useful to you.
If electric fans were really not effective as some suggest they would not have found their way onto countless millions of cars and trucks. If "Expert" opinions were always accepted without question there would be no innovation. There are a lot of members on this forum and the more adventuresome ones have tried a lot of things, some of which worked and some of which didn't.
