Well after much laziness and determination I finally created a BobbyM style keggle mashtun for my direct fire mashtun. Props go to him, as I took his design to a tee.
Here's the keggle wrapped with holes drilled for the thermos and spigots. I had to re-drill them a bit as the original placement was less than perfect.
Here's the finished product. I added some square pieces of aluminum over the holes and riveted them in place and added caulking to make sure no wort ever gets into the wool through the holes.
Then I caulked the hell out of the inner rim of the keggle. Covered the handles too for watertight fit. Lastly I caulked the top of the wool so nothing wet gets in there.
Then I added some reflectix wrap to make the top as insulated as possible. Added 3 layers to slip over the lid and then 3 more on top of the whole thing to fit snug. I have not done heat tests yet. But I am confident to have only a couple degree loss over an hour.
Here's a pic of the back. I opted for a permanent solution instead of the hinges as I felt the hinges were too weak to hold the aluminum sheet together. I had to cinch it down very tight with the racketing straps to get the wool to form fit around the keggle. I thought the rivets would hold better.
Here's a shot from underneath to show the thickness of the wool.
How much did it all cost? I do BIAB in a Keggle on a Top Tier burner... and during the winter months with the cold air blowing around I loose a lot of heat.... also you don't happen to have his original thread handy do you?
please note, most if not all wool insulation is merely Fire resistant, not fire proof.
Well maybe I correct myself here. I imagine a direct flame for extended period of time would cause a problem. But then again this is used for a mashtun, not a boil kettle. As such there is no reason on earth you would be blasting a burner at this which such voracity that flames are licking up the sides.
The stuff is rated to 1200F. I will say that I had my burner (BG-12) on full throttle getting my water to 154F. There were no flames going up the sides and certainly no issue with burning or even a scent or weird smell.