I have an Avalon Mission stove (love it !) 1 year old. It performed amazingly perfect all last winter for us. I heated our whole house with ease. Our house is 1850 square feet 2 story and it kept temps at an average 78 degrees all winter. (rather warm) Here is my stove, (please feel free to remove link if not allowed) http://www.warmingtrendsstoves.com/mission_ws.html I had filled the stove with oak and left damper open one night and I was just getting ready to go down and damper it down because I knew it would be roaring soon. I got downstairs and sure enough it was getting rather hot but not dangerous hot, so I dampered it all the way closed. When you damper all the way closed it will "dance" blue flames all over inside for a pretty long while, it did this as usual and then I decided to open damper a "tiny bit" to keep the heat coming. I then heard a low WHOOSH......not real loud.....kind of like a wadded up news paper you might lay on coals. Then I heard a slight steady rumble...........it started just above my stove and the sound went up my stainless double wall insulated pipe and then stopped almost as quickly as it started, 3 seconds at most. I hurried outsdide and looked at the top of my pipe expecting to see flames but saw nothing, quiet as a mouse. After this, I inspected stove and pipe and could not see or find anything abnormal at all. The pipe never felt any hotter than normal as I checked inside and out. It all happened when I opened damper within a couple seconds after closing when I had a really great fire going.........does anyone know what this could have been ? Thanks for any help. Robbie.