This slows the end-grain drying and limits the severity of end checking. Different species should not be loaded simultaneously into the kiln due to often differing kiln schedules. Conventional kiln drying. Secure .gov websites use HTTPS This helps keep the lumber straight during the drying cycle; in fact, improper placement of stickers can permanently deform lumber. 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. The starter blocks should be as long as the stack is wide. Determine the correct designation, such as T3-D2 for 4/4 red oak. Kiln dried wood typically sells for a third more than green lumber and eliminates the need for . A household dehumidifier (DH) removes moisture from the kiln chamber. 906 0 obj << /Linearized 1 /O 908 /H [ 710 498 ] /L 501020 /E 6532 /N 45 /T 482781 >> endobj xref 906 12 0000000016 00000 n This returns some moisture to the very dry exterior of the lumber, while not affecting the core moisture level. For equalizing, use an EMC 2% below the target MC at a dry-bulb of 170 F. For conditioning, use an EMC 4% above the target MC at a dry-bulb of 180 F. Professor Gene Wengert is Extension Specialist in Wood Processing at the Department of Forestry, University of Wisconsin-Madison. The dry kiln operator is fully in control, with the ability to make changes as the dry kiln schedule is executing. Oregon-based HDE Dry Kilns has launched a new line of small kilns ranging from 2,000 to 12,000 board feet. For end baffles, I use 2"-thick rigid foam insulation screwed to the main baffles. For a single-stack kiln I recommend a minimum shed size of 8 x 12. Job Opportunities and Woodworking Services, Dust Collection, Safety and Plant Operation. If your lumber stack is built on starter blocks, you will need to limit airflow there as well. Select a heater with an adjustable thermostat and a tip-over shutoff. Typical . There are two ways to remove water from the DH unit, and they both work well. . Another great option is to convert an existing shed or outbuilding to a lumber kiln. The DH is not needed at this time, as the lumber is already bone-dry. are generally kiln dried by time scheduleswhether the wood is intended for struc-tural lumber or for appearance uses, such as furniture or millwork. This will allow the DH to drain automatically without you needing to enter the kiln. Should I? In exchange for building the shed myself, I wound up with a shed of higher quality, with more features. Dehumidification Kiln. Manufacturer guarantees/warranties for power tools, CNC and laser products will supersede the Rockler Guarantee if these items are damaged or defective. 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. In larger kilns, the heater may be needed in the latter part of the drying cycle. The kiln humidity can be expressed as an EMC, relative humidity, or wet-bulb temperature. I recently picked up a back issue of American Woodworker, #94 June 2002, that has a good article on constructing a simple DH kiln. Saving money by drying your lumber may not be the answer for every woodworker, but the basics shown here demonstrate that it is within the reach and skills of the average person. Nyle. In the third column, write down the appropriate dry-bulb temperatures. How do I convert from the standard kiln schedules in the USDA's "Dry Kiln Schedules for Commercial Woods" and "Drying Hardwood Lumber" to an SDR-type schedule? Perhaps the best part: you wont need to calculate your lumber needs down to the board foot. organization in the United States. 5. This kicker board will help distribute the airflow more evenly through all layers of lumber. For sterilizing thicker lumber, additional time is required. Total costs for the materials were $2,704 based on 2006 prices. 282 0 obj <> endobj Built properly, a shed kiln may even increase the value of a property. My aim was to develop a small dehumidification kiln for better control of the three key components of lumber drying: temperature, airflow and humidity. This gives me a secondary method of tracking the drying process, using both water volume and moisture content (MC) readings. Share. As the MC drops and I crank the DH on more and more, the temp tends to rise up too high just from the heat the DH throws off, even though the light bulb heaters are not on at that point. 0000001208 00000 n Go to the second number designation (the wet-bulb depression designation) and find the corresponding depressions in the table below. 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.) For a kiln temperature of 140 F, sterilization takes three to five hours. The delicate blue and white color scheme c 4.4 drying schedule moisture content drying schedule . I have been reading & studying kiln schedules for years too. A.gov website belongs to an official government 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. For example, if you dry 7,500BF of fast drying Pine, youd select the 8MBF chamber with the HT18 Dehumidifier. After four days, I decrease the RH setting on the DH to 30% and continue to run the fans. USDA, 1991) . The first load was started with 60% and this load was started with 78%. In a professional DH kiln, the final climate for oak is 120F and <40>t over-dry it at that rate. This would allow a stack of lumber four feet wide and 10 feet long. The moisture loss, drying time and drying defects were determined. I use a Rockler steam generator. Academia.edu no longer supports Internet Explorer. I either use some cedar 3" x 5", or 4" x 4" stock. %3.3 Using a piece of paper with 6 columns, write down the Schedule Step numbers in the first column on the left. If severe enough, the lumber can develop honeycomb cracks throughout. Dehumidification drying system. Low Temperature Kiln Drying Systems (120F) 300BF - 4000BF Capacity . I like these "starter blocks" to raise the lumber a few inches off the floor. I find that unplugging the DH is helpful during the sterilization phase so I can add a second heater, without overwhelming my electrical circuit. You won't ever have the fastest kiln in town, but it can still work. Measure airflow over the stacks of lumber in various locations. 7. An anemometer confirms that your effort constructing baffles was worthwhile. You can achieve top-quality results with incredible efficiency. The company's small kilns can be configured for drying lumber, firewood, or heat-treating lumber or wood packaging. This report contains suggested dry kiln schedules for over 500 commercial woods, both temperate and tropical. Go to the second letter designation (the MC Class Designation) and find the corresponding MC ranges in the table below. I am using a household . Y}-m+'@DQ4\h8GP]y@ yL. This problem is magnified if the lumber is thin or flatsawn. This publication outlines the basic construction of a small scale dehumidification dry kiln. Basically the idea seems to be to maintain a constant temperature, and to keep lowering the humidistat to maintain the SDR until the moisture content gets to the desired level. Basically, you dont want all of the air rushing out under the stack, so find a way to redirect it. My four main baffles consist of sheets of 1 Styrofoam insulation. 6. I then manually rotate the fan boxes halfway through the drying cycle. Wood Drying/ Seasoning. /Filter /JBIG2Decode My kiln schedule starts with running all fans and the dehumidifier for two days, measuring and removing water as it accumulates. Willie Sandry is a furniture maker and a lumber kiln operator in Camas, Washington. Insulation for walls and ceilings should be a minimum of R13. In contrast, a dehumidification kiln uses a sealed chamber, with only enough energy input to maintain the desired temperature. In the fourth column, write down the wet-bulb depressions (determined in #4 above), one for each Schedule Step, starting at the top (Schedule Step 1). A higher humidity setting will run the unit sporadically to maintain that RH. %PDF-1.6 % A shed kiln has minimal venting (usually one or two gable vents) and sealed soffits. Omitting the sterilization phase can lead to costly losses from insect damage, so don't skip it. H6`2}s=n:l)CR>/"\ I know mixed loads are taboo, but this one worked well, other than the horse chestnut. The kiln configuration and a drying schedule can be input and the code in the Excel file will simulate . There might be a problem with that if the chamber overheats and has to be vented because some water will leave that way. Phytosanitary heat treatments of Ceratocystis lukuohia and Ceratocystis huliohia-colonized Metrosideros polymorpha wood were evaluated using kilns. As a result, the kiln schedules were too severe. Lock The fact is, most of my stacks of lumber air dry to 15% moisture content before entering the kiln. Changing the position of the doorway in various kiln setups helps provide the best access to the stacks of lumber. ) or https:// means youve safely connected to the .gov website. Take a moisture reading in the end grain with a pin-type moisture meter or remote probe.) For these reasons, I feel it is best to let the shed breathe, and forgo a plastic vapor barrier. Difficult-to-dry species might not exceed 140 degrees F. Dehumidification kilns are very . Just walk out to the shed kiln and grab what you need from your custom-dried supply. I hope that the sawyer coated the ends of the lumber with Anchor-Seal or oil-based paint when it was green. Remove samples from the stack, and cut an inch or two off one end. I made a simple frame from plywood strips and attached the insulation sheets to them with screws and fender washers. A household dehumidifier (DH) removes moisture from the kiln chamber. Without baffles, the top layers of lumber experience potato chipping with cupping, twisting or warping. Please refer to Appendix A which shows the Lumber Dry Kiln Bill of Materials. The baffles direct airflow over and through the stack and prevent the top layers from drying too quickly. The four charges of lumber ranged from 600 to 700 board feet (bf), and a woodworker with no dry-kiln experience operated the kiln. This slows the end-grain drying and limits the severity of end checking. (116 C) temperature. I guess I am thinking that while I am seeing the wood's MC and the kiln's RH drop smoothly, the fact that the temperature jumps around a bit may mean that the drying rates are hard to control, hence my loss of horse chestnut. If the fans and dehumidifer generate enough heat to maintain a temperature of 100 to 120 F, then I wont use the auxiliary heater. Select 3/4 conduit brackets for hanging baffles on 1/2 galvanized pipe. Dont even think of powering your kiln with an extension cord. At the planer mill, warped 2 by 4's represent a significant loss in value. I also wrapped the shed with Tyvek HomeWrap. Once the core readings are 6% to 8% on a fresh cut, the lumber is dry and ready for sterilization. hb```[@9p(T-3jO:g)@S 4Y]g7l\V!c!$Bf J B@&xcEz8PH@ZHs1/X$qOq,x'x$0.rWg*d XAT10 );9 Vacuum Kiln Drying. I recommend a 2 x 3 sliding window with bug screen. /Height 2587 Align the stickers over the starter blocks on the first course. %PDF-1.5 They are based on different air flow rates, etc. Schedule for drying 4/4 and 5/4 upland red oak in a steam dry kiln. Kiln drying is usually preceded by air drying to bring the moisture content of the wood down below 30%. Both restrained and control boards were dried to approximately 9 percent moisture content, representative of final in-service condi- tions. In-service replacement of warped 2 by 4's as wall studs or truss members is costly. %%EOF I'm thinking I could vent it manually, but with the RH so high externally I am not sure if that is the right thing to do. On this order alone, I saved over $1,300 by drying the lumber myself. Additionally, I have been underwhelmed by the performance of solar-operated fans. -. It should be double-pane, well-insulated with low emissivity (low-E). The common lumber name is used throughout. For end baffles, I use 2-thick rigid foam insulation screwed to the main baffles. 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 Basically the idea seems to be to maintain a constant temperature, and . I was hoping someone could point me in the right direction or share experience. For a kiln temperature of 140 F, sterilization takes three to five hours. Also, since heat rises, ceiling-mounted fans have the added benefit of circulating the warmest air over the lumber. Rep. FPL-GTR-57. Adjust the baffles or fan direction to achieve good airflow. Difficult-to-dry species might not exceed 140 degrees F. Dehumidification kilns are very . Taking moisture away at the rate the board will "safely" part with it . Dr. Gene Wengert provides schedules for kiln drying hardwood lumber. By setting the relative humidity (RH) on the dehumidifier, you can control how often it runs. However, if you kiln dry hardwood lumber that has already been air dried, the process is much more forgiving. I decided on a dehumidification kiln after reading an article in Fine Woodworking (1991). The baffles do not need insulating properties, and plywood would work just as well. KD150 Series dehumidifier pdf manual download. When the operating conditions of this option are followed the material will meet the requirements of being kiln dried (KD) and heat treated . Wood-Mizer dehumidification and solar wood kilns range from 300 to 35,000 board feet capacity for drying lumber. Soon the DH won't show much water collected in the tray. the Dry Kiln Operator's Manual (Simpson, 1991). Instead of using expensive electrically reversible fans designed for commercial kilns, I came up with a simple hardware solution. Also, for that approach to work, the chamber needs to be air tight. (I have found that remotely monitoring the temperature and humidity with a WiFi sensor can be very helpful. During the conditioning process, the only equipment operating are the fans, heater and the steam generator no dehumidifier. Place a 16 board on the floor behind the stack, tilted to a 45 angle. 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). 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 /Width 1628 Wood Shrink/Swell estimator - A web-based program to estimate shrink/ swell in wood. The schedules can also be formulated manually as follows. Unfortunately, little information is available regarding lumber drying technology and practices used, which is essential for the formulation of improvement strategies. Another common sticker size is 1" x 2", and these work fine as well. If you cannot find exact match, look at SG of same family species. Temps are in Celsius (20C = 70F, 40C = 105F). You can achieve top-quality results with incredible efficiency. Job Opportunities and Woodworking Services, Dust Collection, Safety and Plant Operation, Air-Drying and Kiln-Drying Methods for Wide Plank Flooring, Drying lumber - selecting the best method. Initially, I set the DH to 40% RH, because I dont want to remove moisture too quickly. Dehumidification Kilns The air flow rate through your stacks should be about 350FPM. In this system, moist air is not vented out of the kiln but is dehumidified, then recirculated . 0000006274 00000 n Take the electronics out of the kiln, and continue operating the heater and fans during this phase. A typical kiln schedule is a series of temperatures and relative humidities, which are applied at various stages of drying as can be seen in Table 1. . Ideally, a lumber kiln would be large enough to dry multiple stacks of lumber. Case hardening is a defect caused by the outer portion of a board drying quickly, while the inner portion dries more slowly. With a 130 F kiln temperature, sterilization will take 10 to 12 hours ( Dry Kiln Operators Manual, 1991 ). For the best experience on our site, be sure to turn on Javascript in your browser. A maximum 45 F depression often produces better lumber. The approach described in the article where you try to keep the water leaving at a steady rate is fine. The starter blocks should be as long as the stack is wide. Insulate the floor with 2 rigid foam for convenience and durability. Dehumidification kiln schedules 145 Sterilizing, equalizing, and conditioning treatments 145 Sterilizing treatments 145 Mold 145 Fungal stain and decay 146 . Also, since heat rises, ceiling-mounted fans have the added benefit of circulating the warmest air over the lumber. A locked padlock Low temperatures can be used for an extra safety margin on greener lumber. /Subtype /Image If you use a lot of lumber, and youre a decent hand at carpentry, a shed kiln will quickly pay for itself. hbbd``b` $ &UD\q@u 2. In addition, wood can be dried by special methods that include solar drying (use of greenhouse-type dryers or those equipped with solar collectors . This helps keep the lumber straight during the drying cycle; in fact, improper placement of stickers can permanently deform lumber. The T-bars are made from 1/2" galvanized pipe and are attached to the rafters with threaded pipe flanges. Understand how kiln performance must be modified to permit the use of custom schedules for specific product applications; Be able to modify existing conventional kiln schedules to dry products in dehumidifier kilns; Recognize degrades common to various species, including hardwoods, and modify handling practices to minimize these 3. More than 75 percent of the existing hardwood dry kilns in the United States are steam heated, are humidity controlled and have reversible fans inside the kiln. 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. A heavy-duty 1,500-watt space heater works fine. I hope that the sawyer coated the ends of the lumber with Anchor-Seal or oil-based paint when it was green. Dr. Gene Wengert provides schedules for kiln drying hardwood lumber. (Dry Kiln Operator's Manual. During the conditioning process, the only equipment operating are the fans, heater and the steam generator no dehumidifier. If the fans and dehumidifer generate enough heat to maintain a temperature of 100 to 120 F, then I won't use the auxiliary heater. _0e`bd\ p@ Heres a classic project that both steps up and provides overflow seating. 73. Custom Doors, Drawers & Glass Accessories, Using a Small Scale Dehumidification Kiln, Learn Woodworking Tips & Tricks with Rockler, High-quality brands and products you can trust, Expert advice and free post-purchase support, Exclusive, innovative products that help you Create with Confidence, Detailed instructions, technical specs and guides to make the most of your purchases. . Kiln drying lumber is a simple, cost effective method recommended for anyone who wants to increase profits by selling dried lumber. The column on the right I added part way through is the kiln's internal RH. Dehumidification kilns from Nyle Systems in Brewer, Maine. Installing a window in a kiln may seem counterintuitive at first, because windows lose more heat than an insulated wall. In addition, weight on top of the stack can be helpful, but nothing replaces baffles for the best lumber yield. For a small scale shed kiln, I recommend a maximum footprint of 200 square feet. After four days, I decrease the RH setting on the DH to 30% and continue to run the fans. They are easy to use and give you precision control over your drying. Such temperatures are high enough to kill insectsanother advantage of kiln drying over air drying. The schedule designations use the popular U.S. Forest Products Laboratory designations. Take the electronics out of the kiln, and continue operating the heater and fans during this phase. Once the lumber is sterilized, it is ready for the conditioning phase. However, because wood from 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. 0000002827 00000 n Windows and doors are also sealed, as well as any holes cut for electrical service. So, with that lengthy introduction, here is my question. Most species of hardwood lumber can be safely dried this way, once the moisture content is 20% to 25% or less. 3.) These figures hold true for lumber up to 2" thick. 0000006297 00000 n A free BASIC program to convert the designations into actual temperatures and humidities is available from the author. 9. You can download the paper by clicking the button above. After two days operating only the fans and DH, I take note of the temperature. In addition, weight on top of the stack can be helpful, but nothing replaces baffles for the best lumber yield. For a kiln temperature of 140 F, sterilization takes three to five hours. 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. Apply foil tape to the edges of the main baffles to help protect the Styrofoam. Once all the lumber is stacked and stickered, place baffles over the lumber. The four charges of lumber ranged from 600 to 700 board feet (bf), and a woodworker with no dry-kiln experience operated the kiln. For single-stack kilns, stationary fans are adequate. Drying lumber too quickly can lead to deep end checking, warping and case hardening. Place a sticker at each end, and every 16 along the stack for 4/4 stock. endstream endobj startxref They are easy to use and give you precision control over your drying. 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 . 0000004213 00000 n Staff. I usually see a large volume of water in the DH each night when I check the kiln. . Gen. Tech. This makes lightweight baffles that can be easily moved and repositioned.