roy kirkpatrick wrote:Aww man don't tell me that so you are suggesting to use fire brick alone?
I think the feed and burn tunnel are ok, it is the riser, the top of the riser mostly where maximum heat is. It looks to me like you have stuffed the riser with some sort of insulating clay stuff, so provided you have stuffed it tight enough to be smooth against the pipe you used as a form most of it should be ok. The metal form will burn out and the clay stuff will last ok. But the last two inches of the form stick up over the the clay mix and will probably melt/burn off. This will change your gap

The outside of the riser will be fine, much cooler. It is the riser liner that needs the heat protection, so if your insulating layer is up to it, everything else looks fine. I would have liked to see the insulating goop go to the top of the riser form in one go. Adding that last bit later may make the top few inches some what fragile, but if it isn't moving it may be ok. This is all assuming that is a clay based mix.
condensation in the bench pipes will happen until the surface temperature is past 212F. One of the burn products is water. Cob is partly insulating and so will allow the flue surface to rise more than when it is bare. Also a normal burn is 3 hours or more.