Ben,

Maybe you can answer this question. When I took the NHIE, there was a picture that I had to describe. I had no earthly idea what it was. I do know it was some type of system. The way I can describe it was that it was sort of round and it looked like on the top it had either fins or like fan blades. Can you identify it as to it might be since you have been in the home inspection for some time?