dehumidification kiln drying schedulesdehumidification kiln drying schedules

During the conditioning process, the only equipment operating are the fans, heater and the steam generator no dehumidifier. Soon the DH won't show much water collected in the tray. A better choice might be a solar kiln, as you can dry wood from "wet" to 6-8 percent MC in 6-8 weeks. Initially, I set the DH to 40% RH, because I dont want to remove moisture too quickly. When properly loaded, this kiln can dry approximately 600 board feet of 4/4" lumber. Over 40 years experience building kilns. The first charge of mixed air-dried 4/4 hardwoods and softwoods was kiln-dried from 18.4% to 7.3% moisture content (MC) in 15 days with no . - Model L300, L500, L1200-S Series - Medium Dehumidification Dry. Forum Responses Gen. Tech. Small, complete dehumidification dry kilns under 5,000 board-foot capacity are not available for sale. The baffles do not need insulating properties, and plywood would work just as well. In addition, weight on top of the stack can be helpful, but nothing replaces baffles for the best lumber yield. Willie Sandry is a furniture maker and a lumber kiln operator in Camas, Washington. Official websites use .gov Case hardening is a defect caused by the outer portion of a board drying quickly, while the inner portion dries more slowly. An anemometer confirms that your effort constructing baffles was worthwhile. Hb```f``:A2,@!p"4|QP(y;ysc6f{f+&FfKi-L4+i`Vlf nwj2MM/E)rQ,^wm{'_B&%F`dbt JB*UWTmdIb& z P"f#*E4% @BHA!4I( I0 !`Hke0 PQI ([@R R`0 &xgTh( *p1 ~L{ endstream endobj 917 0 obj 389 endobj 908 0 obj << /Type /Page /Parent 892 0 R /Resources << /Font << /F0 909 0 R /F1 912 0 R >> /ProcSet 915 0 R >> /Contents 913 0 R /MediaBox [ 0 0 607 792 ] /CropBox [ 0 0 607 792 ] /Rotate 0 >> endobj 909 0 obj << /Type /Font /Subtype /TrueType /Name /F0 /BaseFont /CenturySchoolbook,Bold /FirstChar 31 /LastChar 255 /Widths [ 750 287 296 333 574 574 833 852 241 389 389 500 606 278 333 278 278 574 574 574 574 574 574 574 574 574 574 278 278 606 606 606 500 747 759 778 778 833 759 722 833 870 444 648 815 722 981 833 833 759 833 815 667 722 833 759 981 722 722 667 389 606 389 606 500 333 611 648 556 667 574 389 611 685 370 352 667 352 963 685 611 667 648 519 500 426 685 611 889 611 611 537 389 606 389 606 750 750 750 241 574 481 1000 500 500 333 1000 667 333 1000 750 750 750 750 241 241 481 481 606 500 1000 333 1000 500 333 907 750 750 722 287 296 574 574 606 722 606 500 333 747 367 500 606 333 747 500 400 549 344 344 333 576 747 278 333 344 367 500 861 861 861 500 759 759 759 759 759 759 981 778 759 759 759 759 444 444 444 444 833 833 833 833 833 833 833 650 833 833 833 833 833 722 759 611 611 611 611 611 611 611 870 556 574 574 574 574 370 370 370 370 611 685 611 611 611 611 611 549 611 685 685 685 685 611 667 611 ] /Encoding /WinAnsiEncoding /FontDescriptor 910 0 R >> endobj 910 0 obj << /Type /FontDescriptor /FontName /CenturySchoolbook,Bold /Flags 16418 /FontBBox [ -250 -215 1079 962 ] /MissingWidth 671 /StemV 149 /StemH 149 /ItalicAngle 0 /CapHeight 962 /XHeight 673 /Ascent 962 /Descent 215 /Leading 202 /MaxWidth 899 /AvgWidth 468 >> endobj 911 0 obj << /Type /FontDescriptor /FontName /CenturySchoolbook /Flags 34 /FontBBox [ -250 -220 1200 951 ] /MissingWidth 756 /StemV 84 /StemH 84 /ItalicAngle 0 /CapHeight 951 /XHeight 665 /Ascent 951 /Descent 220 /Leading 171 /MaxWidth 1000 /AvgWidth 463 >> endobj 912 0 obj << /Type /Font /Subtype /TrueType /FontDescriptor 911 0 R /BaseFont /CenturySchoolbook /FirstChar 31 /LastChar 255 /Widths [ 750 278 296 389 556 556 833 815 204 333 333 500 606 278 333 278 278 556 556 556 556 556 556 556 556 556 556 278 278 606 606 606 444 737 722 722 722 778 722 667 778 833 407 556 778 667 944 815 778 667 778 722 630 667 815 722 981 704 704 611 333 606 333 606 500 333 556 556 444 574 500 333 537 611 315 296 593 315 889 611 500 574 556 444 463 389 611 537 778 537 537 481 333 606 333 606 750 750 750 204 556 389 1000 500 500 333 1000 630 259 1000 750 750 750 750 204 204 389 389 606 556 1000 333 1000 463 259 833 750 750 704 287 296 556 556 606 704 606 500 333 737 334 426 606 333 737 500 400 549 333 333 333 576 606 278 333 333 300 426 833 833 833 444 722 722 722 722 722 722 1000 722 722 722 722 722 407 407 407 407 778 815 778 778 778 778 778 606 778 815 815 815 815 704 667 574 556 556 556 556 556 556 796 444 500 500 500 500 315 315 315 315 500 611 500 500 500 500 500 549 500 611 611 611 611 537 574 537 ] /Encoding /WinAnsiEncoding >> endobj 913 0 obj << /Filter /FlateDecode /Length 914 0 R >> stream Dehumidification: This kiln-drying process requires the use of a heat pump system to remove water from the wood. Each layer of lumber is separated from the next by a series of stickers or spacer sticks. Air speed of 350 feet per minute is appropriate for common hardwoods such as oak and maple. In larger kilns, the heater may be needed in the latter part of the drying cycle. I use a Rockler steam generator. Dehumidification Kilns I had these custom cut and I air dried them outside under a tarp for 6 to 18 months (depending on which load they came in on) and then I kiln dried them in a Nyle dehumidification kiln for 3 months. 0000000710 00000 n Dehumidification Kiln. 0000002827 00000 n This will allow the heater to cycle on and off automatically, according to the kiln operator's setting. Also, for that approach to work, the chamber needs to be air tight. This makes lightweight baffles that can be easily moved and repositioned. Operates at a temperature range from 80F - 160F (26 - 71C). In-service replacement of warped 2 by 4's as wall studs or truss members is costly. Keenan Slab Works has a vacuum kiln located at 4917 Elizabethtown Road, Manheim, Lancaster County, Pennsylvania, 17545 and is expanding services for the general public to have their slabs and lumber vacuum dried. After two days operating only the fans and DH, I take note of the temperature. Many articles have been dedicated to solar lumber kilns: everything from a simple sheet of Visqueen over a stack of lumber in the sunshine to elaborate enclosures designed for solar gain. Ideally, a lumber kiln would be large enough to dry multiple stacks of lumber. 0000000591 00000 n /BitsPerComponent 1 A lower RH setting will call for the DH to run more often. /Name /ImagePart_0 If your lumber stack is built on starter blocks, you will need to limit airflow there as well. 6. Hardwood lumber kiln drying schedules typically keep the dry bulb temperature below 180 F (82 C). John Baines Reply to Dann Barry 1 year ago Culm parts with 2.0 and 2.2 m length after pressure treatment were dried in industrial kilns using three schedules with mild, severe and highly severe drying intensity. Go to the second number designation (the wet-bulb depression designation) and find the corresponding depressions in the table below. Changes in kiln temperatures and humidities are based on the MC of the lumber being dried, which in turn is determined from properly prepared kiln samples. 1998. by Dr. Eugene Wengert. After four days, I decrease the RH setting on the DH to 30% and continue to run the fans. Also, you can't really control well by measuring the collected water because some of the water leaks out with vented or leaking air. For these reasons, I feel it is best to let the shed breathe, and forgo a plastic vapor barrier. So, if you have 100 bf in the kiln, every 12 hours you would extract (12 hours *100bf * .0061 SDR) = 7.3 pints of water. Appendix B . The following tables show some examples of oak schedules for steam dry kilns and dehumidification dryers. Not bragging or anything! Attic fans are a perfect way to provide airflow over the stacks of lumber. You can download the paper by clicking the button above. Just walk out to the shed kiln and grab what you need from your custom-dried supply. With two-stack and three stack kilns, it is better to have reversible fans to alter the direction of airflow mid-cycle. I like these starter blocks to raise the lumber a few inches off the floor. A heavy-duty 1,500-watt space heater works fine. Sticker spacing can be increased to 24" apart for 5/4 or thicker hardwood. My shed kiln was stick-built from standard building material, and sized to take advantage of typical 4 x 8 sheet goods. 2. This gives me a secondary method of tracking the drying process, using both water volume and moisture content (MC) readings. << The problems with solar kilns include limited control over temperature and limited solar exposure, depending on your region and site location. For example, if you dry 7,500BF of fast drying Pine, youd select the 8MBF chamber with the HT18 Dehumidifier. The last thing to do before starting the kiln is to close the gable vent with an insulated cover. However, if you kiln dry hardwood lumber that has already been air dried, the process is much more forgiving. Always avoid conditions that add moisture back to the lumber, especially during start-up. You won't ever have the fastest kiln in town, but it can still work. This lets the operator sort stacks by lumber species, so they will be easy to retrieve when the drying cycle is complete. The order was 540 board feet (BF) of 5/4 white oak. Kiln drying lumber is a simple, cost effective method recommended for anyone who wants to increase profits by selling dried lumber. Another reason I like the idea of a shed kiln is the flexibility of future use. If MC readings still arent at the desired range, the heat may need to be increased for the remainder of the drying cycle. 0000006274 00000 n In the third column, write down the appropriate dry-bulb temperatures. Equalizing and Conditioning You could use the dehumidifier to dry wood but it would not be part of a "kiln." Just be a different process. noun: kiln; plural noun: kilns. Kiln dried wood typically sells for a third more than green lumber and eliminates the need for . Wood Shrink/Swell estimator - A web-based program to estimate shrink/ swell in wood. If it isn't overheating, it is leaking. Our approach was to build and operate a small dehumidification dry kiln. 3, a simplified transverse section of a kiln chamber with an energy recovery and dehumidification system is shown. This helps keep the lumber straight during the drying cycle; in fact, improper placement of stickers can permanently deform lumber. Reweigh and obtain the oven dry weight. Consider not only the space for the lumber stacks, but extra floor space to easily load and monitor the charge of lumber. Such temperatures are high enough to kill insectsanother advantage of kiln drying over air drying. A lower RH setting will call for the DH to run more often. Milling the stickers square is advantageous over a rectangular cross-section, because no matter how you place the stickers they will form a level stack. Abstract. Dehumidification dry kilns operate at lower drying temperatures (typically below 150F) than do conventional kilns, which results in longer drying schedules. 6. Sorry, preview is currently unavailable. Dehumidifier suggestion: http://amzn.to/2iYZqVZThis is the first in a series of videos showing how I built a kiln for drying lumber. 44. JavaScript seems to be disabled in your browser. Nyle Systems dehumidification kiln packages are our best known product with nearly unlimited drying capabilities. Extruded polystyrene foam (blue or pink rigid foam) in this thickness has an R value of 10. Excel Program for Modeling Lumber Dry Kiln Operations - a model for lumber dry kiln operation. %%EOF The store will not work correctly in the case when cookies are disabled. Milling the stickers square is advantageous over a rectangular cross-section, because no matter how you place the stickers they will form a level stack. I can show you the kiln schedules and data. There are two ways to remove water from the DH unit, and they both work well. Ignoring for a moment the merits of a homebrew DH kiln versus a Nyle, I was curious to see that rather than referencing the standard kiln schedules (e.g. Additionally, I have been underwhelmed by the performance of solar-operated fans. They are normally mounted in the gable of household attics, and they are designed to be used in high temperature environments. The Bolivian wood products industry was surveyed to determine lumber drying capacity, technology and. Also check that air isnt escaping around the side baffles or under the stack of lumber. noun. The T-bars are made from 1/2" galvanized pipe and are attached to the rafters with threaded pipe flanges. /Subtype /Image On this order alone, I saved over $1,300 by drying the lumber myself. The sheetrock also helps to protect the fiberglass insulation. My baffles hang from T-bar assemblies mounted to the ceiling. The moisture loss, drying time and drying defects were determined. It is a meaningless exercise to try to convert those schedules for the kiln you built. When the drying is done in a kiln, the product is known as kiln-dried timber or lumber, whereas air drying is the more traditional method.. Select a heater with an adjustable thermostat and a tip-over shutoff. A higher humidity setting will run the unit sporadically to maintain that RH. 6 0 obj (Sawing and Drying Forum) End baffles are also a good idea to prevent airflow from bypassing the stack entirely. 0000004213 00000 n A kiln schedule is a set of temperatures and humidities that are used during kiln operation. Minus the drying equipment, a shed kiln is just an insulated storage space, with a host of possible uses. Drying lumber too quickly can lead to deep end checking, warping and case hardening. A small "m" after the designation indicates that the wet-bulb temperatures should be adjusted to avoid temperatures below 90 F. See the above mentioned publication for details. Enter the email address you signed up with and we'll email you a reset link. This problem is magnified if the lumber is thin or flatsawn. A small electric heater supplies auxiliary heat to maintain adequate kiln temperature. The thinner the stock, the more critical sticker placement becomes. Solar kiln drying was most effective in the summer and early fall, when kiln efficiencies were 90% to 67%, respectively, and drying times were 2 to 3/one-half/ times faster than air drying. I don't remember how the air flow was arranged in the kiln in the magazine, but it sounds like that could be a problem for you. This makes lightweight baffles that can be easily moved and repositioned. Share sensitive information only on official, secure websites. For all kiln drying schedules, a heater should be used to sterilize the lumber and kill any insects that may be present. The starter blocks should be as long as the stack is wide. This report contains suggested dry kiln schedules for over 500 commercial woods, both temperate and tropical. This can create internal stress in the lumber that is released when sawing. If your lumber stack is built on starter blocks, you will need to limit airflow there as well. A pre-hung steel exterior door is ideal in this situation, because it offers weatherstripping and is fully insulated. . In addition, wood can be dried by special methods that include solar drying (use of greenhouse-type dryers or those equipped with solar collectors . https://www.fs.usda.gov/research/treesearch/9635, International Institute of Tropical Forestry, Eastern Forest Environmental Threat Assessment Center, Northern Institute of Applied Climate Science, Western Wildland Environmental Threat Assessment Center, conventional-temperature (< 180 F) schedules, elevated-temperature (180-212 F) schedules, R. Sidney Boone, Charles J. Kozlik, Paul J. Bois, Eugene M. Wengert. This serves a dual purpose of supporting the rigid foam insulation as well as stiffening the floor framing. For all kiln drying schedules, a heater should be used to sterilize the lumber and kill any insects that may be present. Warp in dimension lumber is a significant cause for loss in grade and value. Soon the DH wont show much water collected in the tray. As a result, the kiln schedules were too severe. On the last load of lumber I purchased, I saved $2.50 per board foot compared to retail prices for kiln-dried lumber. This returns some moisture to the very dry exterior of the lumber, while not affecting the core moisture level. If for any reason you are not satisfied with the merchandise you ordered, just return it within 90 days to receive a refund in the manner of original payment for merchandise only. Insulation for walls and ceilings should be a minimum of R13. Bring your moisture meter to confirm. The kiln humidity can be expressed as an EMC, relative humidity, or wet-bulb temperature. An anemometer confirms that your effort constructing baffles was worthwhile. By setting the relative humidity (RH) on the dehumidifier, you can control how often it runs. With a well-designed dehumidification kiln, hardwood lumber can be dried for mere pennies per board foot. But kiln drying may also introduce internal stresses into the woodparticularly if an improper kiln schedule is used, . To hang the baffles, simply attach hooks to the plywood frame. 301 0 obj <>stream /Height 2587 Select 3/4 conduit brackets for hanging baffles on 1/2 galvanized pipe. Temperatures inside the kiln range from 120 to 190 degrees F, depending on the stage of . Unfortunately, little information is available regarding lumber drying technology and practices used, which is essential for the formulation of improvement strategies. This prevents dead spots inside the chamber that experience limited airflow. Kiln drying is usually preceded by air drying to bring the moisture content of the wood down below 30%. Kiln drying is the process of drying wood in a controlled environment, where temperature, air circulation and humidity are monitored and stabilized. Also, since heat rises, ceiling-mounted fans have the added benefit of circulating the warmest air over the lumber. This slows the end-grain drying and limits the severity of end checking. Difficult-to-dry species might not exceed 140 degrees F. Dehumidification kilns are very . HWn8gXA N,[mKJr2"Ec9,t hTn8>_l7h.&E:Bem=C9n\8]lMPc. Remove samples from the stack, and cut an inch or two off one end. I chose double wall construction with 1/2 sheathing, and 1/2 T1-11 siding. I prefer to empty the water tray manually and record the volume of water collected. txN.a!HQ)FmCw~{B1Aq_!+zN#+j It should be double-pane, well-insulated with low emissivity (low-E). Also, today, we are often kiln drying No.2 Common lumber which requires a milder schedule than upper grades; in the 1950s, seldom was this lower grade lumber kiln dried.) The second most common type of drying is called dehumidification drying. The delicate blue and white color scheme c 1998. For the sterilization phase, air temperature needs to be around 140 F, for three to five hours. Once the core readings are 6% to 8% on a fresh cut, the lumber is dry and ready for sterilization. If you dry 9,500BF of slower drying Oak, youd use the 10MBF chamber with the HT8 Dehumidifier. . For a kiln temperature of 140 F, sterilization takes three to five hours. November 1, 2020. . Should I? 0000002536 00000 n Among dimension lumber, the 2- by 4-inch size is typically the most susceptible to warp for a variety of reasons. For end baffles, I use 2"-thick rigid foam insulation screwed to the main baffles. My question focuses on the initial relative humidity featured in the Safe Drying Rate table. Instead of using expensive electrically reversible fans designed for commercial kilns, I came up with a simple hardware solution. I have sensors in the kiln for moisture levels & probes in the center of the wood attached to a lignomat moisture meter. 4. I dont think the same could be said for an old reefer truck converted into a kiln (no matter how well it dries lumber). Loading the kiln begins by rousing my sons and letting them know Ive planned a day of work. Once all the lumber is stacked and stickered, place baffles over the lumber. Installing a window in a kiln may seem counterintuitive at first, because windows lose more heat than an insulated wall. the hardwood kiln schedule is the equalization of the moisture content of all boards at 6-8%. From contributor D: For the best experience on our site, be sure to turn on Javascript in your browser. A lazy Susan with 180 detents mounts the fan box to the ceiling. After seven to 10 days, I reverse the fan direction to make sure all stacks of lumber dry evenly. The conversion method described in the Dry Kiln Operator's Manual is not really accurate, but it is safe. These figures hold true for lumber up to 2" thick. This allows for a more gentle kiln schedule to fully dry the timber. With each load I did not have the initial relative humidity rate. Corrosion resistant epoxy coated aluminum cabinets and specially coated dehumidification coils for an extra long life. Staggering the seams between the sheathing and siding layers helps avoid air infiltration. I use a Rockler steam generator, item #42826 (www.rockler.com). /Length 7 0 R Place the sample board in the lumber stack in a location where it will dry at the same rate as the rest of the lumber in the dryer (see Figure C). Place the one inch sections in an oven 215F to 218F (102C to 103C) and dry - usually 18 to 36 hours depending on the oven. The membrane was taped and lapped to the weather so if the tape ever fails, any rain that gets behind the siding would still be shed down and away by the HomeWrap. Projects included design, construction, installation and commissioning of heat-pump based dehumidification equipment for seafood and fish gelatin products, hardwood lumber kilns and laboratory testing. Matched to one of our L-Series and HT Dehumidifiers they can handle whichever species you are drying, fast drying softwoods to slow drying hardwoods. Should a Moulding Mill Bring Sawmill Operations In-House? Maderas. trailer << /Size 918 /Info 891 0 R /Root 907 0 R /Prev 482770 /ID[<67858f68421814977b05bc7913f6cc23><4073af979fbabe8f1c016146fd1c21ef>] >> startxref 0 %%EOF 907 0 obj << /Pages 902 0 R /Type /Catalog /DefaultGray 903 0 R /DefaultRGB 904 0 R /Metadata 905 0 R >> endobj 916 0 obj << /S 499 /Filter /FlateDecode /Length 917 0 R >> stream A.gov website belongs to an official government Manufacturer guarantees/warranties for power tools, CNC and laser products will supersede the Rockler Guarantee if these items are damaged or defective. Choosing a Kiln Schedule . of this publication is to make available to dry kiln operators and others interested in kiln-drying wood, kiln schedules that are completely assembled and written out for ready reference and easy use. For a single-stack kiln I recommend a minimum shed size of 8 x 12. Chinese, Korean or Japanese kilns have an arch roof. Made in China, it exudes the classic style of Asian and Chinese cultures, featuring a unique shape that sets it apart from traditional jars. The KD150 Dehumidification Kiln Kit is a compact, entry-level dehumidification kiln for drying lumber between 300 and 1000 board feet. Rep. FPL-GTR-57. (I have found that remotely monitoring the temperature and humidity with a WiFi sensor can be very helpful. Schedules for several thicknesses and specialty products (e.g. Created and Presented by: Henco Viljoen and Elijah McCarty with Nyle Dry Kilns. Main thing is to not rush drying in first stages, as this will cause problems. The first thing to consider when designing a shed kiln is size. Its a nice use of technology and adds a measure of safety as well.) A household dehumidifier (DH) removes moisture from the kiln chamber. For a kiln temperature of 140 F, sterilization takes three to five hours. If you intend to kiln dry lumber from a green state, right off the sawmill, you will need to be well-versed in airflow rates and follow a detailed drying schedule.
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