I have a homemade 2x6 evaporator I love. Conventional fire box with grates and a draft door under the grates. I cook at my remote cabin with no electricity, never will be.

I've been thinking about air over fire. My wood stove at the cabin has what I call passive air over fire. Air is drafted in from the back of the stove, pulled up over the fire and injected into the fire box thru a header with holes directed toward the front door. When the fire is going good, there is a lot of turbulence over the fire, burning gases and improving efficiency. It works very well.

My thought is to do something similar on my evaporator. My initial thought is drill holes thru the side walls of the firebox 6" below the top. Thought I would match the air over fire open area on the header of my wood stove using 1/4 or 3/16" ID pipe. Might be 15 or 20 pipes. Smaller diameter to increase air velocity and turbulence hopefully.

Anyone do anything similar? Any other thoughts? I've read all about blowers and auf/aof. Not gonna work for me. Thanks.