I just installed an Avalon Zero Clearance insert and am on my second burn. It is an older model and has a fan. When I turn on the fan there is a what my wife calls a "Heat, old" smell? I smell it too, but her sense of smell is better than mine and it does not bother me. I cleaned off the fan when I bought it. Any ideas what this might be and how me might get rid of it so we can use the fan?