I have a guru controlled UDS that has been working perfectly for several years, but needed something MORE - a smokehouse (a small one anyway). Loving my UDS, and guru, decided last year to try to marry the two into a smoke house. It worked, but not so well. So this year tried version 3 (version 2 was bandaids on version 1).
I would love to be showing you pictures of a perfectly working version 3, my mini-maxi UDS. I worked amazing for almost 1.5 hours. Then failed in epic proportions. Only luck had me catch it in time to save the smokehouse from the fire department...
It's design worked perfect, going to temp and maintaining possibly easier than my UDS - so I will describe the good, before getting to the bad.
It is a tightly built, double walled smokehouse, clad in tin. The walls are vented on the top of the inside, and on the bottom - turning them into a heat exchanger. The exhaust smoke maintains the temp of the outside of the inner wall. My smoke generator was essentially a tiny UDS made out of a tamale pot. The guru provided air via a whole in the floor of the smoker and the floor of the tamale pot. Putting the mini UDS inside insured every last calorie of heat made it into the smokehouse. While not relievent to the design, cold smoke could also be piped in through the fresh air plumbing (if I ever wanted to cold smoke-just hook a hose to the chimney of my original UDS. I got cheap and did the elbow in the floor via a small wood box under the floor...
Well after working apparently perfectly for almost an hour and a half, the failures were very apparent - the floor was burnt through and it was on fire. The steamer shelf in the tamale pot (that I was using for a grate) melted, dumping the fully ignited coals onto the bottom of the pot (and possibly directly into the wooden box below due to the air vent hole). The pot's bottom then melted, so one way or another - coal was on wood in the path of the blower. The airbox was completely on fire (and all the wood under the pot was gone) when I managed to get the fire extinguished.
No real damage was suffered to the smokehouse itself (minimal scorching of some of the frame supporting the floor), so all I have to do is replace the floor and air ducting (to the guru fan). Had the fire gotten to the edge of the floor into the heat exchanger in the walls - it would have been a total loss).
Ok, rebuilding with a steel L rather than wooden airbox, steel floorpan, metal grait and stainless steel pot (30 quart). So much for smoking a few hundred lbs of sausage this week... Thank God I did a test run and caught this disaster as early as I did, and Thank God it happened (so I can build a safer version).
Will post again once this thing is up and running.