Continuous Kilns and Minimum Board Feet Question

[M Gallahar]

What is the minimum board feet of drying per month required to make a continuous kilns feasible?

[GeorgeCulp]

Mostly depends on the length of the CDK. If your lumber we'll say requires 30 hours to dry then if you have a 60 foot kiln then your push rate would be 2 feet per hour. If you have a 30 foot kiln then the push rate would be 1 foot per hour.

Those are extreme examples yet should serve to show you how "how much board footage is required" is a question you can answer yourself.

[M Gallahar]

Thanks, George.

Do you use a continuous kiln? Anything I should be aware of? Any advice?

[GeorgeCulp]

Sorry to be so slow on reply, I don't check the board very often..

Other things you should know...... running a different thickness on each tract could be a problem especially if you change either or both and also depending on the difference in the thicknesses. If you run 4/4 on one track and 7/4 on the other there won't be much change in airflow as compared to if either thickness was on both tracks but there will be some. If one track is 7/4 and the other 4" or 6" timbers there will be a great difference in drying but you'll have to determine that on your own. The thicker side track will have a higher air flow rate but use less than half of the total heat per unit of time. The thinner side track will have lower airflow and use more than half of the heat per unit of time. The point is if you change conditions from same thickness on both tracks to different thicknesses on each tract you must pay attention closely.

I have some concern about the hot moisture migrating down to the conditioning chamber. I feel it is a very good thing but my concern is with the uniform distribution or lack there of rather. I hear reports of very uniform drying so either the hot moisture is evenly distributed or its not making much difference.

Having no real baffles at the doors I think negates some of the conditioning chamber as being useful as hot air escapes the high pressure side and cold air is sucked in on the low pressure side. One mill I visited said that in their kiln there was no drying in the last 15' of the kiln before exiting.

[M Gallahar]

Thanks, George.