Ok Ive been losing a lot of heat out my exhaust stack .Ive been thinking about adding another tank to the top to help catch some of the heat . My old wood bruner had one on top and it helped a lot .My exhaust stack is around 400 degs . Ive been thinking about maybe a 15-25 gal tank . I saw a air tank off of a large truck that looks like it may be what I'm looking for . Any one tried this yet ?