Shopping for a Dehumidifying Kiln

If you consider getting a European-made dehumidifying kiln for use in the U.S., make sure it's compatible with U.S. power supply voltages. June 16, 2014

Question
I'm looking at getting a small kiln to start drying our own lumber. Has anyone tried the Logosol Sauno kilns? They are nearly half the price of the Nyle L53, but the spec sheet says they dry almost 50% more lumber. Does the heat/steam offer a significant advantage to speed or stress relief of the wood?

Forum Responses
(Sawing and Drying Forum)
From Gene Wengert, forum technical advisor:
I have not seen this kiln. I some info and there must be an error as it stated that softwoods can be dried from 17% to furniture dry is a week. That seems very long indeed. I cannot figure if this is a steam kiln or DH. Maybe it is both. Does this unit have to be outside the kiln and then ducts and pipes run into the kiln? Does it come with controls?

The following facts might help your evaluation. To evaporate the water and to have energy for heat losses from a building means that we need about 4-5 million BTUís from green to 7% MC per MBF. That means that at 100% efficiency and a drying time of 20 days, we need 250,000 BTUís a day or 10,000 BTU per hour. That is about 3 kW per hour. So, at 100% efficiency (no boiler loss, etc.), we would find that 3000 watts will dry 1000 bf of green lumber in 20 days. Actual kiln time might be longer due to heating up, equalization or conditioning. Of course, heat flow is actually not even throughout the run, so it might take a bit longer than 20 days. If it is a DH kiln, then 30000 watts per hour energy use would be less so it might dry 1700 bf or so in 20 days or so.

Steaming before drying with green lumber is well known and there is an active patent that likely covers this. I would be concerned enough that for any kiln steaming wet lumber I would get a statement that if sued for infringement someone else will cover legal expenses, fines, etc. If it does not infringe, then no problem. Steaming of fairly dry lumber to remove stresses is well known and called conditioning. Such steaming would not speed drying however. So, it will be interesting to see what this is all about and what the energy use is, etc.



From the original questioner:
From what little I could find it seemed like people are being asked to air dry their hardwoods, especially oak before putting them in the Sauno kiln. This does seem overly long to me. Apparently Logosol hasn't even published drying schedules for their unit. I'm currently air drying my wood before taking it to a large facility for drying, but this seems mostly due to the fact they are loading it in with whatever else they are drying. With the Nyle kiln I've been led to believe I should be putting most hardwoods in the kiln directly, and expect it to dry according to their published schedules. It seems like the Nyle kilns, even their smallest the L53 are far quicker units. Am I wrong here?


From Gene Wengert, forum technical advisor:

Nyle kilns or just about any kiln can accept air dried lumber. Air drying may have more quality loss, however, due to unfavorable weather - too dry, too wet and too windy.


From Gene Wengert, forum technical advisor:
Incidentally, the comments I gave about the facts of drying apply to all drying, except vacuum, and not just to one type of kiln or manufacturer.


From the original questioner:
I'm going to go with the Nyle kiln. An L200 came up used locally. Itís more expensive, seems more tried and true and has a better capacity anyways.