I've been wondering what the proper flame height should be and consideration for setting it to a different setting. The Mt Vernon AE was purchased new on 12/04/2007, it has been working great. The flame height is presently set at "0". I have option of -5 to +5. Hope someone can give me more information. As I have read the manual which doesn't explain why I would need to change it. I may not be getting all that I can out of this stove at it's present setting. While I'm at it I also have the temp deferential set at 1 during the cold days and 3 when it isn't so cold. I live in Central Maine we have had a colder then normal Dec and are looking at sub zero temps the next two days. Appreciate the impute.