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Thread: Building lumber kiln

  1. #1

    Building lumber kiln

    Hello everyone. I don't usually go for advice, but that's the field I'm not experienced enough to make well-considered decision. I need a bit of advice from someone experienced in building kiln (30x25 ft.). What equipment do we need to remotely control humidity and tempreature inside. We can build and isolate the room, that's not the problem, but what electronics should be considered. Dehumidifiers, fans, heaters? Share your experience and budget if you had a deal with such project

  2. #2
    Join Date
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    Thomas, Iíve built several kilns. To provide the best advice, Iíll need to know whaat species and thickness that you plan on drying, and how many board feet at a time. Also need to know if you are planning to dry from green or if you will be drying material that has already been air dried.

  3. #3
    Hello, fresh cut red oak of different dimensions from 4/4 to 12/4. so I guess I'll need several (3) different chambers and probably different equipment, I thought about purchasing some of these dehumidifiers and some kind of moisture controllers with remote access to data. I thonk now these dehumidfiers are home-type models, and I will need something more powerful, right?

  4. #4
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    The issue with dehumidifiers is not power, itís sustainability. Kiln environments can be very corrosive, and home dehumidifiers wonít last long in that environment.

    4/4 red oak is around a 4-5 week kiln run in a DH kiln; 8/4 is 3.5 months and 12/4 would require years.

    You might want to consider a two faceted approach. Build a solar kiln as a pre-drier, and a small DH kiln to finish off and sterilize. Alternatively you may be able to dry everything in solar and then build a sterilization chamber.

    A 30í x 25í kiln chamber could easily hold 4000 bd ft, give or take. Your best bet would be to purchase an appropriately sized commercial kiln unit, such as a Nyle L200 or one of the EBAC kilns. Another choice would be to go vacuum. The new iDry kilns work very well with most species (except white oak). They are inexpensive as far as vacuum kilns go (around 50K), but still a lot more expensive than a Nyle.

    The L200ís have options to manage the drying rate based upon temperature and RH%, as opposed to the older wet bulb / dry bulb style. Also all of their components are suitable for operating in a kiln environment for many years.

  5. #5
    Join Date
    Dec 2015
    Location
    Milwaukie, OR
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    41
    Hi Thomas,

    Scott has a lot more experience and I'd trust his advice. The obvious first challenges I had were making a structure that was insulated enough (R30?) and sealed tight.

    I have a EBAC L200 and can vouch for it. FOr the price I thought it was a better buy then the comparable Nyle unit. I tried using some home and industrial dehumidifiers for a DIY DH kiln. The problems I ran into were 1) the durability factor that Scott described, 2) standard dehumidifiers have a "dew point" of around 98 degrees F. Above those temps they don't work efficiently and you need to get the temperature up to a sustained 110-120 degrees to properly dry the wood.

    Another major factor that I have had to learn through trial and error is good air-flow. If you go with the EBAC L 200 it will come with two good size fans that will provide a decent start for good air flow over the top of the stacked wood. A fully stacked 30' x 25' size kiln is going to need more moving air then those 2 fans alone can provide. My kiln is 16' wide x 12' deep x 12 x high and I have extra fans on the front of the stacks to get air flow through the stickered wood and back to the dehumidifier. It seems to work but I still have to check for wet pockets on some of the bigger slabs we dry.

    Another piece of the puzzle for me was figuring out how to get wood into and out of the kiln. I've created a metal track and rack system that I can push/pull the stacks with my forklift.

    Good luck!

    David M.
    Milwaukie Hardwoods, LLC

  6. #6
    30'x25' is HUGE you are quite brave to start with such a large kiln.
    Airflow airflow and more airflow. We started with a shipping container without enough airflow and i had mold growing on my short leaf pine. I now build projects out of "denim pine"
    Here's a small dehumidifier kiln from the forest products lab. You can see the basic principles
    https://www.google.com/url?sa=t&sour...yf3c_hOkAh_CZS

  7. #7
    Quote Originally Posted by David Mealey View Post
    Hi Thomas,

    I have a EBAC L200 and can vouch for it. FOr the price I thought it was a better buy then the comparable Nyle unit.
    Isn't "L200" a Nyle model #? Do you maybe have a Nyle LD800? I'm zero'ing on a unit purchase and chasing down reviews on these units.

    Thanks!

  8. #8
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    Quote Originally Posted by Neal Sacon View Post
    Isn't "L200" a Nyle model #? Do you maybe have a Nyle LD800? I'm zero'ing on a unit purchase and chasing down reviews on these units.

    Thanks!
    Yes, L200 is a Nyle model. It is designed for 4000 bd ft of 4/4 oak (from green), around 1,500 bd ft of 4/4 poplar or pine, 3000 bd ft - give or take of 4/4 walnut or maple, etc.

    The Woodmizer 4000 series is based upon a Nyle L200.

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