I have two booster fans in my home that I use to blow hot air to the second floor when it's cold. One of them has recently died and I need a replacement. What are you guys using in your homes? My grate is roughly 10" x 10" with a fan size of 6" however, I cannot find anything similar to it anymore. My units have square duct work inside with the fan built into it. Here is a picture of the grate...
