Why Tunnel Fans with Butterfly Shutters may not be a Good Investment?

Dr. Mike Czarick you may also have a look at DACS that makes a motorized insulated door, called MagDoor, that you install inside the barn. With a exterior fan cover for winter should be good to go. Probably not the cheapest way upfront, but figuring how much energy is wasted + fan corrosion, it may be well worth. Here in Quebec, as most of other Canadian provinces, because our winters are very cold, we use interior shutters that we replace in cold weather with a interior insulated rigid closure panel. Maybe you could add a framing around up your fans and add this kind of panel ? Good luck