WFO "Outer Door"
So, I did finally get around to building my "outer door". Most of our ovens are heavily insulated on 5 of the six sides, but the front, for practical reasons, does usually appear somewhat "exposed". I use my oven once a week to bake about 140 loaves for the local Farmer's Market. My objective was to keep as much heat as possible in the oven between my weekly bakes. I had my local welding shop make me a metal plate that would be big enough to cover the exposed front of the oven. The edges are bent in for 2 inches, to support the insulation and keep the welding blanket from wearing through over a sharp edge. I filled it with 4 inches of high-heat insulation and left an "indentation" for the handle of the door (since my door is very well insulated with Foamglas, it stays in place when not baking). I covered the insulation with a welding blanket and screwed that welding blanket onto the edge (think large chair cushion). A couple of handles to lift it in and out of the chimney opening, and we're good to go. After baking, I set it in place and push it as closely as I can to the oven wall (it makes contact with the wall on the top). I don't have any good numbers yet, since I am still changing my firings with the increased demands in terms of number of loaves and the amount of heat I need in the outer layers, but I think I can tell it makes a difference. How much, remains to be seen, but once I fire my oven more consistently I can take some better readings and compare them to a week without having the outer door on.
A view from the side - roughly 4 inches thick.
View from the front with the two handles. The gunk in the middle is soot coming down from the chimney when we have a good downpour (that's WITH a raincap!).
And here the outer door is in place. I had an internal temp of 475 after I was done baking on Monday morning at 4:00am. Right now, Friday night at 7:00pm, it's at 235 degrees.