This limits the amount of energy needed to bring lumber to the desired 6% to 8% moisture content. Case hardening is a defect caused by the outer portion of a board drying quickly, while the inner portion dries more slowly. 3. Every Nyle Dehumidification Dry Kiln System Example: If the WBT falls below the set parameter measures and regulates internal kiln conditions the system will turn on the spray system. MC values in the kiln schedules are based on the wettest half of the kiln samples. Anyway, I included my log of a load I did in Nov '06 for everyone's amusement. Kiln drying is almost always essential for wood intended for interior uses. USDA, 1991) . Corrosion resistant epoxy coated aluminum cabinets and specially coated dehumidification coils for an extra long life. For a kiln temperature of 140 F, sterilization takes three to five hours. 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. Two-by-four material sawn from young trees, thinnings, and stem tops contains a significant proportion of juvenile wood and is particularly notorious for warp. My aim was to develop a small dehumidification kiln for better control of the three key components of lumber drying: temperature, airflow and humidity. Then align each subsequent layer of stickers over the last. Loading the kiln begins by rousing my sons and letting them know Ive planned a day of work. This makes lightweight baffles that can be easily moved and repositioned. If it isn't overheating, it is leaking. My kiln uses four ceiling-mounted fans, each rated for 1,600 CFM. Typical dehumidification kiln (FPL 1999 p. 12-10). Dehumidification: This kiln-drying process requires the use of a heat pump system to remove water from the wood. The second most common type of drying is called dehumidification drying. Subtract the wet-bulb depression from the dry-bulb temperatures for each schedule step and enter the value in the fifth column. 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. If severe enough, the lumber can develop honeycomb cracks throughout. Then, write down the appropriate MC ranges (determined in #2 above) in the second column. I either use some cedar 3" x 5", or 4" x 4" stock. Temps are in Celsius (20C = 70F, 40C = 105F). For single-stack kilns, stationary fans are adequate. . I hope that the sawyer coated the ends of the lumber with Anchor-Seal or oil-based paint when it was green. With a 130 F kiln temperature, sterilization will take 10 to 12 hours (Dry Kiln Operators Manual, 1991). A dehumidification kiln continuously recycles the heat throughout the chamber, rather than . 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. Any small building could work, as long as it has a minimum of 2 x 4 framing, and will seal out unwanted air. Rep. FPL-GTR-57. . Consider the weight of the lumber that will be placed in the structure and fortify the building accordingly. Loading the kiln begins by rousing my sons and letting them know Ive planned a day of work. Joining end grain to long grain forms the king of joints. Reply. End baffles are also a good idea to prevent airflow from bypassing the stack entirely. _0e`bd\ p@ Would adding humidity at the start, bringing the initial relative humidity rate to 87% as suggested in the table, result in better product or faster drying? This air space is absolutely critical for even airflow, so count on the extra floor space right from the design phase. Different species should not be loaded simultaneously into the kiln due to often differing kiln schedules. Should a Moulding Mill Bring Sawmill Operations In-House? In this paper, the effective schedules were further investigated for longer culm parts treated with boron. Forum Responses In contrast, a dehumidification kiln uses a sealed chamber, with only enough energy input to maintain the desired temperature. An anemometer confirms that your effort constructing baffles was worthwhile. This slows the end-grain drying and limits the severity of end checking. My shed kiln was stick-built from standard building material, and sized to take advantage of typical 4 x 8 sheet goods. For a kiln temperature of 140 F, sterilization takes three to five hours. Dehumidification Opportunities for Dehumidification Drying Of Hardwood Lumber Dimension Kiln Drying Hardwood Dimension Parts Discoloration Preventing Discolorations in Hardwood and Softwood Logs . After seven to 10 days, I reverse the fan direction to make sure all stacks of lumber dry evenly. Construction of a kiln chamber is very similar to building a small house. 0000000591 00000 n Once the core readings are 6% to 8% on a fresh cut, the lumber is dry and ready for sterilization. A discussion of how to apply "safe drying rate" calibrations with a home-built dehumidifying kiln. The column on the right I added part way through is the kiln's internal RH. For the best experience on our site, be sure to turn on Javascript in your browser. Add up the amp draw on all the equipment you plan to use in the kiln, including a heater, dehumidifier, fans and steam generator. Not bragging or anything! T8-C3 or similar for hard maple), the article instead provided a table showing the "safe drying rates" (SDR) for a number of species. JavaScript seems to be disabled in your browser. WOODWEB is a registered trademark of Woodweb.com. I hope that the sawyer coated the ends of the lumber with Anchor-Seal or oil-based paint when it was green. Kiln dried wood typically sells for a third more than green lumber and eliminates the need for . Dehumidification drying equipment is available, but an enclosure must be built to house the equipment and dry the lumber. Go to the first number designation (the temperature designation) and find the corresponding temperatures in the table below. A lower RH setting will call for the DH to run more often. Hardwood kiln drying schedules typically keep the dry bulb temperature below 80 C (176 F). A 1.5-kW dehumidifier was installed in the solar dryer to determine the performance of a combined solar-dehumidification dryer. In Fig. Looking at the cost-benefit analysis of a shed kiln can be enlightening. Schedules for several thicknesses and specialty products (e.g. The first load was started with 60% and this load was started with 78%. The thinner the stock, the more critical sticker placement becomes. Small, complete dehumidification dry kilns under 5,000 board-foot capacity are not available for sale. My kiln uses four ceiling-mounted fans, each rated for 1,600 CFM. I like these "starter blocks" to raise the lumber a few inches off the floor. In this system, moist air is not vented out of the kiln but is dehumidified, then recirculated . The schedules can also be formulated manually as follows. 10. Remove samples from the stack, and cut an inch or two off one end. I modified one of the Radio Shack combo units so it could measure the RH remotely as well as the temp. 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. For sterilizing thicker lumber, additional time is required. Dehumidification drying system. A locked padlock My baffles hang from T-bar assemblies mounted to the ceiling. Main thing is to not rush drying in first stages, as this will cause problems. 0 \ This procedure is discussed in a following section. Equalizing and conditioning are required for almost all hardwood lumber. Chinese, Korean or Japanese kilns have an arch roof. 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. Choosing a Kiln Schedule Do not know just how the end point of moisture would compare. This prevents dead spots inside the chamber that experience limited airflow. During the conditioning process, the only equipment operating are the fans, heater and the steam generator no dehumidifier. (I have found that remotely monitoring the temperature and humidity with a WiFi sensor can be very helpful. Instead of using expensive electrically reversible fans designed for commercial kilns, I came up with a simple hardware solution. kiln/. Its a nice use of technology and adds a measure of safety as well.) Apply foil tape to the edges of the main baffles to help protect the Styrofoam. The velocity through the load is assumed to be between 275 and 350 fpm, except for the white woods (including maple, ash, basswood, hackberry) where higher velocities (up to 600 fpm) are desired and acceptable. By setting the relative humidity (RH) on the dehumidifier, you can control how often it runs. We are proud of the quality of our products, and we stand behind them 100%. 1. 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 By setting the relative humidity (RH) on the dehumidifier, you can control how often it runs. 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. Once the flooring deck is constructed, think about sealing the shed framing at every opportunity. (Note: This letter designation is related to the green MC of the species. The kiln process involves the drying of wood in a chamber where air circulation, relative humidity and temperature can be controlled so that the moisture content of wood can be reduced to a target . This gives me a secondary method of tracking the drying process, using both water volume and moisture content (MC) readings. Gen. Tech. (Sawing and Drying Forum) Align the stickers over the starter blocks on the first course. A dehumidification kiln makes sense particularly when the lumber is air-dried first. hbbd``b` $ &UD\q@u 0000001417 00000 n Evaluation of kiln-drying schedules for wild cherry wood (Cerasus avium), Model to assess energy consumption in industrial lumber kilns, Mathematical modelling and experimental investigation of dehumidifier drying of radiata pine timber, A survey of Bolivian lumber drying operations, Warp reduction of SYP lumber by restrained drying, Western Juniper Drying Project Summaries, 1993-96, Vacuum contact drying kinetics of Jack pine wood and its influence on mechanical properties: industrial applications, Kiln drying behavior of lumber from ten fast-growth plantation species in Costa Rica, Effect of fire-retardant treatment and redrying on the mechanical properties of Douglas-fir and aspen plywood, Properties of Douglas-Fir and Aspen Plywood, A numerical study on the influence of the bond-line diffusivity on moisture-related stresses and deformations of three-layered spruce cross-laminates, Error in Estimates of the Moisture Content of White Oak Kiln Sample Boards, Green Kerfing Treatment for Improving Softwood Lumber Drying: A Review, A comparison of kiln-drying schedules and quality outcomes for 4/4-thickness black cherry lumber sawn from small-diameter logs, A comparison of kiln-drying schedules and quality outcomes in 4/4-thickness black cherry lumber sawn from small-diameter logs, Data bank for short-length red oak lumber, Hardwood lumber widths and grades used by the furniture and cabinet industries: Results of a 14-mill survey, Lumber and veneer recovery from intensively managed young-growth Douglas-fir, WOOD-FRAME HOUSE CONSTRUCTION U.S. DEPARTMENT OF AGRICULTURE FOREST SERVICBAGRICULTURE HANDBOOK NO. A free BASIC program to convert the designations into actual temperatures and humidities is available from the author. 293 0 obj <>/Filter/FlateDecode/ID[<87A322ACC143C740A97F712BC6C2FBCD>]/Index[282 20]/Info 281 0 R/Length 68/Prev 378162/Root 283 0 R/Size 302/Type/XRef/W[1 2 1]>>stream 6 0 obj From contributor D: Drying lumber too quickly can lead to deep end checking, warping and case hardening. (I have found that remotely monitoring the temperature and humidity with a WiFi sensor can be very helpful. Wood drying (also seasoning lumber or wood seasoning) reduces the moisture content of wood before its use. Take the electronics out of the kiln, and continue operating the heater and fans during this phase. Operates at a temperature range from 80F - 160F (26 - 71C). I dont think the same could be said for an old reefer truck converted into a kiln (no matter how well it dries lumber). /Name /ImagePart_0 Can also be used on any mobile device! 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. I prefer to empty the water tray manually and record the volume of water collected. I opted not to install a true vapor barrier between the framing and sheetrock, because of potential condensation and mold issues with sheds constructed this way. Enter the email address you signed up with and we'll email you a reset link. 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. If we revisit the example of a $1,300 gross savings from a load of 540 BF of white oak lumber, and we subtract the estimated cost of $62 to kiln dry the lumber, we arrive at a net savings of $1,238 less than retail. Lock Share. %3.3 The water tray can be removed and emptied manually, or a hole can be drilled through the wall of the shed to pass a drain tube. 0000001186 00000 n Dehumidification kilns are similar to other kilns in basic construction and drying times are usually comparable. This lets the operator sort stacks by lumber species, so they will be easy to retrieve when the drying cycle is complete. However, if you kiln dry hardwood lumber that has already been air dried, the process is much more forgiving. My kiln schedule starts with running all fans and the dehumidifier for two days, measuring and removing water as it accumulates. The T-bars are made from 1/2" galvanized pipe and are attached to the rafters with threaded pipe flanges. Made in China, it exudes the classic style of Asian and Chinese cultures, featuring a unique shape that sets it apart from traditional jars. A small electric heater supplies auxiliary heat to maintain adequate kiln temperature. Created and Presented by: Henco Viljoen and Elijah McCarty with Nyle Dry Kilns. This gives me a secondary method of tracking the drying process, using both water volume and moisture content (MC) readings. Additionally, I have been underwhelmed by the performance of solar-operated fans. Seems like a pretty simple way to run the kiln - once or twice a day just measure the amount of water extracted, and turn down the humidity a bit as needed. My kiln schedule starts with running all fans and the dehumidifier for two days, measuring and removing water as it accumulates. This slows the end-grain drying and limits the severity of end checking. In-service replacement of warped 2 by 4's as wall studs or truss members is costly.