Simple kiln

[CX3]

If I had a wood stove, that had an enclosed metal box around it, and blew the hot air into a basically airtight shed stacked with green lumber, and an escape hole out the back of the shed for air to escape , or am I underthinking this?

[YellowHammer]

It's a basic principal that heated and evacuated air will dry wood.  However, just adding uncontrolled heat will result in kiln dried firewood rather than high quality lumber.  Other parameters have to be controlled, such as airflow and velocity through the stacks, the humidity in the chamber, as well as the temperature.  In other words, several factors that control the rate of drying must be manipulated in a true lumber kiln, and heat is an important factor, but only one of them. 

[Ianab]

Yeah, the simple uncontrolled part is the problem. You risk drying the wood too fast (if the air is too warm and venting too much). and then you get all sorts of checking, case hardening etc.

A solar kiln can get away with simple controls because it's intermittent. It dries well for maybe 8 hours, then the sun goes down and the wood can relax and recondition, ready for the next days cycle.  Maybe you could arrange something similar, where you only run the burner for a few hours, then let the system cool off overnight?

I would start by looking at how the solar kiln designs work, with the fans, baffles and vents, and maybe modify that to work with your warm air source?

[CX3]

Ok, I figured I was too simple. I just have several people wanting KD lumber, it is definitely something I need to research.

[YellowHammer]

Best, easiest, is a solar kiln. Very simple to operate, hard to screw up, and will have a fair output during the sunny months.  Otherwise, even a small Nyle will dry a surprising amount of wood.