That set-up with the pit style smoke generator is a classic cold smoker design that has been in use for hundreds of years. In the old days, every farm had a smoke house and that is the basic design. The elevation of the chamber is the key to get the draw just right. The distance from the generator is what allows the smoke to cool down. Earth is a great insulator so I bet there is little adjustment from summer to winter. I wish I had the room for something like that. I would love to be able to do my own bacon, hams and smoked sausages. It looks like that drum is galvanized. I guess since temperatures will be below 85° it is not an issue like we worry about in a drum used for barbecuing.
This is one of Warren Anderson's homemade smokers with a separate smoke generator. It is a knock-down model. He has plans for several cold smokers he designed in his book Mastering the Craft of Smoking Food.
He also discusses hot smoking, cures, supplies and sausages.
KCBS - CBJ
Big Green Eggs, Big Drum Smokers, Big Chiefs, Weber Smokey Joe "Custom Tall Boy"
Oil Patch Horizontal
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Barbecue is not rocket surgery