Im debating about installing an oak on my Castile insert and have read countless threads on this forum and have found one Castile insert owner that did and noticed that it wasn't drawing in any cold air from the outside or very minimal because of the design of where it attaches to the stove. As you know if you have one that where it enters underneath by the ash drawer that its not a sealed system. I just don't want to waist the time and money to do it if its not worth it.