After a summer in New England that felt more like Fall I opened my Englander 25 PVD to discover that a large portion of the inside exposed steel had a fine coating of RUST. I tried scraping the surfaces with the putty knife that I use for cleaning the ash from these same surfaces but the orange hue of rust remains. Should I be concerned and more importantly will this hinder the transfer of heat from the rusted metal surface. I was thinking I should run some steel wool with a little elbow grease to see if I could get it off. Open to suggestions and helpful advice.