We are having a lot of flies lately coming into the house from the door from the house to the garage. Standard size 36 inch wide door. I wanted to use a contacts sensor that turns on a fan via a smart plug to blow air over the door. Like an air curtain at stores, hotels, and restaurants.
Anyone have any ideas on how to make this so it flows like a thin curtain of air over the door?
Air curtains can be great, but I don’t think you can easily replicate one with a regular fan.
To keep bugs out, you want a thin continuous flow of air pointing down over the doorway for the full width of the door.
Most room fans have a much stronger blast of air over a much narrower area and would be really hard to mount safely. (And would look pretty awful.)
I would just get a system designed for this purpose with a magnetic door sensor built in. There are several brands available under $275.
This is just one example.
Depending on the exact model you are considering, there would be different ways to smarten it further if you want, but I would start with a fan designed for the purpose. 