dehumidification kiln drying schedules

dehumidification kiln drying schedules

/Width 1628 44. There are many types of kilns, but the most common are dehumidification kilns and conventional kilns. 1998. by Dr. Eugene Wengert. Q,kjifT33P[! It is a meaningless exercise to try to convert those schedules for the kiln you built. Instead of using expensive electrically reversible fans designed for commercial kilns, I came up with a simple hardware solution. Another common sticker size is 1" x 2", and these work fine as well. JavaScript seems to be disabled in your browser. Dr. Gene Wengert provides schedules for kiln drying hardwood lumber. /Type /XObject Place a 1x6 board on the floor behind the stack, tilted to a 45 angle. 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. Remote operation and networking is optional. 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. . Thus, a drying program can be adapted according to the characteristics of the kiln load, e.g., species, dimensions, and moisture content. 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? Once the lumber is sterilized, it is ready for the conditioning phase. Diy dehumidifier kiln time table. /Subtype /Image Hardwood lumber kiln drying schedules typically keep the dry bulb temperature below 180 F (82 C). The dry kiln operator is fully in control, with the ability to make changes as the dry kiln schedule is executing. Check your local building codes for regionally specific requirements and electrical permits. 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.) 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. . Temps are in Celsius (20C = 70F, 40C = 105F). However, if you kiln dry hardwood lumber that has already been air dried, the process is much more forgiving. Among the various sizes of southern yellow pine (SYP) dimension lumber, 2 by 4 is produced in the greatest volume. (A major source was Dry Kiln Schedules for Commercial Woods which is available from the Forest Products Society in Madison, WI.) << Once all the lumber is stacked and stickered, place baffles over the lumber. The sheetrock also helps to protect the fiberglass insulation. I modified one of the Radio Shack combo units so it could measure the RH remotely as well as the temp. Once the flooring deck is constructed, think about sealing the shed framing at every opportunity. But kiln drying may also introduce internal stresses into the woodparticularly if an improper kiln schedule is used, . Once the lumber is sterilized, it is ready for the conditioning phase. Also, since heat rises, ceiling-mounted fans have the added benefit of circulating the warmest air over the lumber. There is a way to do the conversions and there is a chart published by Nyle to do it, if you want to do some academic exercise. 0000006297 00000 n hTn8>_l7h.&E:Bem=C9n\8]lMPc. Add to my manuals. Standard kiln drying temperatures are low - around 120 degrees Fahrenheit or so, and drying times vary by wood size and moisture level. In addition, wood can be dried by special methods that include solar drying (use of greenhouse-type dryers or those equipped with solar collectors . I am also curious why an initial temperature of 90F would have been selected. Schedules for several thicknesses and specialty products (e.g. This helps keep the lumber straight during the drying cycle; in fact, improper placement of stickers can permanently deform lumber. These figures hold true for lumber up to 2" thick. Heres a classic project that both steps up and provides overflow seating. Kiln drying lumber is a simple, cost effective method recommended for anyone who wants to increase profits by selling dried lumber. BE CAREFUL--The first temperature value must be repeated for every MC class (column #2) that is above 30% MC. We proudly stand behind all of our products. /Height 2587 Soon the DH won't show much water collected in the tray. 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.. For all kiln drying schedules, a heater should be used to sterilize the lumber and kill any insects that may be present. For the sterilization phase, air temperature needs to be around 140 F, for three to five hours. For international returns, please click here. In vacuum kiln trials, logs were heated to 56C at 70 percent log radius depth and the temperature maintained for . . - Model L300, L500, L1200-S Series - Medium Dehumidification Dry. A lazy Susan with 180 detents mounts the fan box to the ceiling. Omitting the sterilization phase can lead to costly losses from insect damage, so dont skip it. These well-known dehumidification kiln packages have been among our bestselling products for the past 30 years. For end baffles, I use 2"-thick rigid foam insulation screwed to the main baffles. Items shipped directly from the manufacturer cannot be returned in store. Another reason I like the idea of a shed kiln is the flexibility of future use. Website Content Copyright 2023 Nyle Systems |. Wood-Mizer dehumidification and solar wood kilns range from 300 to 35,000 board feet capacity for drying lumber. Official websites use .gov The Bolivian wood products industry was surveyed to determine lumber drying capacity, technology and. Looking at the cost-benefit analysis of a shed kiln can be enlightening. Contractors work on a tight schedule, and that may not allow much time for curing and drying concrete. A better choice might be a solar kiln, as you can dry wood from "wet" to 6-8 percent MC in 6-8 weeks. High Temperature Kiln Drying Systems (160F) Loads up to 350,000 BF; Pull up to 20,000 pounds of water daily; Use standard drying schedule; Precision temperature and RH . Take a moisture reading in the end grain with a pin-type moisture meter or remote probe. Temperatures inside the kiln range from 120 to 190 degrees F, depending on the stage of . They are easy to use and give you precision control over your drying. For example, if you dry 7,500BF of fast drying Pine, youd select the 8MBF chamber with the HT18 Dehumidifier. Different species should not be loaded simultaneously into the kiln due to often differing kiln schedules. >> I'm trying to find a timetable or drying schedule for the basic dehumidification kilns you see on youtube. Know how to choose and apply the correct schedule for the 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. Soon the DH wont show much water collected in the tray. They are based on different air flow rates, etc. This problem is magnified if the lumber is thin or flatsawn. Make sure the total amp draw is well within the limit of your electrical circuit. HWn8gXA N,[mKJr2"Ec9,t Measure airflow over the stacks of lumber in various locations. A shed kiln has minimal venting (usually one or two gable vents) and sealed soffits. Also, you can't really control well by measuring the collected water because some of the water leaks out with vented or leaking air. Table 1 shows a typical drying schedule for sugar maple. In this system, moist air is not vented out of the kiln but is dehumidified, then recirculated . This procedure is discussed in a following section. ) or https:// means youve safely connected to the .gov website. A household dehumidifier (DH) removes moisture from the kiln chamber. Dehumidifier suggestion: http://amzn.to/2iYZqVZThis is the first in a series of videos showing how I built a kiln for drying lumber. . 0000003109 00000 n In a professional DH kiln, the final climate for oak is 120F and <40>t over-dry it at that rate. Then align each subsequent layer of stickers over the last. With a 130 F kiln temperature, sterilization will take 10 to 12 hours ( Dry Kiln Operators Manual, 1991 ). Your order will come with a return form with convenient instructions, or you may send your returns directly to Returns Department, Rockler Woodworking and Hardware, 4365 Willow Drive, Medina, MN 55340. 0000001186 00000 n 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. You can achieve top-quality results with incredible efficiency. Loading the kiln begins by rousing my sons and letting them know Ive planned a day of work. A kiln schedule is a set of temperatures and humidities that are used during kiln operation. They are normally mounted in the gable of household attics, and they are designed to be used in high temperature environments. 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. A household dehumidifier (DH) removes moisture from the kiln chamber. A small electric heater supplies auxiliary heat to maintain adequate kiln temperature. The last thing to do before starting the kiln is to close the gable vent with an insulated cover. Another common sticker size is 1 x 2, and these work fine as well. Among dimension lumber, the 2- by 4-inch size is typically the most susceptible to warp for a variety of reasons. The baffles direct airflow over and through the stack and prevent the top layers from drying too quickly. 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. Using a piece of paper with 6 columns, write down the Schedule Step numbers in the first column on the left. For 4/4 hard maple, with an initial temperature of 90F and an initial relative humidity of 81%, the SDR was given as .0061 pints per hour per board foot. Both restrained and control boards were dried to approximately 9 percent moisture content, representative of final in-service condi- tions. 9. The schedules can also be formulated manually as follows. Oregon-based HDE Dry Kilns has launched a new line of small kilns ranging from 2,000 to 12,000 board feet. 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 /BitsPerComponent 1 4. My baffles hang from T-bar assemblies mounted to the ceiling. A 1.5-kW dehumidifier was installed in the solar dryer to determine the performance of a combined solar-dehumidification dryer. A heavy-duty 1,500-watt space heater works fine. When that is the case, I know Ill have usable lumber in just a few weeks. Dr. Gene Wengert provides schedules for kiln drying hardwood lumber. For a single-stack kiln I recommend a minimum shed size of 8 x 12. Another great option is to convert an existing shed or outbuilding to a lumber kiln. This would allow a stack of lumber four feet wide and 10 feet long. Wood Shrink/Swell estimator - A web-based program to estimate shrink/ swell in wood. 4.4 drying schedule moisture content drying schedule . )f7haRoMRhib5Sd|-=RBkBBN r-hzf+1\IFgk;v]3_, KxL$9oL "Qw#"BFGfk}>cT2g yP K|7@N*v9!Wy9jB. op(y"X)Fz"q]fQC/ha>7=k_p}}^VXQmj e'2fyXQ{~23X^H1,d>Hq|^KQ*cN=yF%z. The last thing to do before starting the kiln is to close the gable vent with an insulated cover. 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. Our approach was to build and operate a small dehumidification dry kiln. This will allow the DH to drain automatically without you needing to enter the kiln. Our capacities are 4,000 board feet in a kiln . An anemometer confirms that your effort constructing baffles was worthwhile. Without baffles, the top layers of lumber experience "potato chipping" with cupping, twisting or warping. 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. 158 p. Dry kiln schedules for commercial woods : temperate and tropical. Construction of a kiln chamber is very similar to building a small house. Minus the drying equipment, a shed kiln is just an insulated storage space, with a host of possible uses. 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. I usually see a large volume of water in the DH each night when I check the kiln. This shed will be essentially unheated for much of the year and very hot during the kiln-drying cycles. The order was 540 board feet (BF) of 5/4 white oak. In the majority of cases, the drying schedules are from the world literature, with emphasis on U.S., Canadian, and British publications. There are two ways to remove water from the DH unit, and they both work well. For sterilizing thicker lumber, additional time is required. A pre-hung steel exterior door is ideal in this situation, because it offers weatherstripping and is fully insulated. Difficult-to-dry species might not exceed 140 degrees F. Dehumidification kilns are very . I prefer to empty the water tray manually and record the volume of water collected. When properly loaded, this kiln can dry approximately 600 board feet of 4/4" lumber. Maderas. I either use some cedar 3" x 5", or 4" x 4" stock. At the end of the cycle I have the opposite problem. This makes lightweight baffles that can be easily moved and repositioned. After four days, I decrease the RH setting on the DH to 30% and continue to run the fans. Kiln drying is the process of drying wood in a controlled environment, where temperature, air circulation and humidity are monitored and stabilized. This will allow the DH to drain automatically without you needing to enter the kiln. Main thing is to not rush drying in first stages, as this will cause problems. This prevents dead spots inside the chamber that experience limited airflow. The stickers are uniform in size and usually 3/4" or 1" square. Always avoid conditions that add moisture back to the lumber, especially during start-up. Share sensitive information only on official, secure websites. kiln/. End baffles are also a good idea to prevent airflow from bypassing the stack entirely. I also wrapped the shed with Tyvek HomeWrap. Such temperatures are high enough to kill insectsanother advantage of kiln drying over air drying. These figures hold true for lumber up to 2 thick. Apply foil tape to the edges of the main baffles to help protect the Styrofoam. Joining end grain to long grain forms the king of joints. This will allow the heater to cycle on and off automatically, according to the kiln operator's setting. 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. This gives me a secondary method of tracking the drying process, using both water volume and moisture content (MC) readings. Operates at a temperature range from 80F - 160F (26 - 71C). Sign In Upload. Dont even think of powering your kiln with an extension cord. Sticker spacing can be increased to 24" apart for 5/4 or thicker hardwood. The following tables show some examples of oak schedules for steam dry kilns and dehumidification dryers. You can download the paper by clicking the button above. A free BASIC program to convert the designations into actual temperatures and humidities is available from the author. Most species of hardwood lumber can be safely dried this way, once the moisture content is 20% to 25% or less. With advances in spray foam insulation, it may be possible to seal older, drafty structures as well. Determine the correct designation, such as T3-D2 for 4/4 red oak. txN.a!HQ)FmCw~{B1Aq_!+zN#+j A higher humidity setting will run the unit sporadically to maintain that RH. Always use adequate samples representing both the wettest and driest lumber in the dryer. Basically, you don't want all of the air rushing out under the stack, so find a way to redirect it. The velocity through the load is assumed to be between 275 and . Dehumidification kilns from Nyle Systems in Brewer, Maine. Corrosion resistant epoxy coated aluminum cabinets and specially coated dehumidification coils for an extra long life. Most species of hardwood lumber can be safely dried this way, once the moisture content is 20% to 25% or less. %3.3 A shed kiln is an attractive alternative for a couple of reasons. The thinner the stock, the more critical sticker placement becomes. Omitting the sterilization phase can lead to costly losses from insect damage, so don't skip it. Adjust the baffles or fan direction to achieve good airflow. Drying small amounts of lumber using a dehumidification kiln is a suitable option for woodworkers even with limited knowledge of kilns. 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. A dehumidification kiln makes sense particularly when the lumber is air-dried first. Detailed design and custom manufacture of dehumidification and chiller systems for food processing, lumber drying and industrial applications. Go to the first number designation (the temperature designation) and find the corresponding temperatures in the table below. Select 3/4 conduit brackets for hanging baffles on 1/2 galvanized pipe. At the planer mill, warped 2 by 4's represent a significant loss in value. I then manually rotate the fan boxes halfway through the drying cycle. Reweigh and obtain the oven dry weight. Schedule for drying 4/4 and 5/4 upland red oak in a steam dry kiln. Corners where walls meet should be sealed with expanding foam sealant. Nyle Systems dehumidification kiln packages are our best known product with nearly unlimited drying capabilities. If the interior volume of a kiln becomes too large, basic heaters and home dehumidifiers may be inadequate to control the kiln environment. For all kiln drying schedules, a heater should be used to sterilize the lumber and kill any insects that may be present. Add up the amp draw on all the equipment you plan to use in the kiln, including a heater, dehumidifier, fans and steam generator. This air space is absolutely critical for even airflow, so count on the extra floor space right from the design phase. If you dry 9,500BF of slower drying Oak, youd use the 10MBF chamber with the HT8 Dehumidifier. The kiln humidity can be expressed as an EMC, relative humidity, or wet-bulb temperature. If the temperature is below this range, I start the heater and adjust the thermostat accordingly. /Name /ImagePart_0 The second temperature value is written for the 25 to 30% MC class; the third for the 20 to 25% MC class; and so on. WOODWEB is a registered trademark of Woodweb.com. 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). In addition, weight on top of the stack can be helpful, but nothing replaces baffles for the best lumber yield. After seven to 10 days, I reverse the fan direction to make sure all stacks of lumber dry evenly. In smaller kilns, the heat generated by the fans and DH motor is sufficient to maintain temperatures in excess of 100 degrees. 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. As a result, the kiln schedules were too severe. On this order alone, I saved over $1,300 by drying the lumber myself. Take the electronics out of the kiln, and continue operating the heater and fans during this phase. The KD150 Dehumidification Kiln Kit is a compact, entry-level dehumidification kiln for drying lumber between 300 and 1000 board feet. The delicate blue and white color scheme c Remove samples from the stack, and cut an inch or two off one end. Chinese, Korean or Japanese kilns have an arch roof. For a small scale shed kiln, I recommend a maximum footprint of 200 square feet. A dry kiln needs to be operated when it is filled with lumber and forces airflow through the tiers of lumber instead of around the ends or over the top of the stack(s). During the conditioning process, the only equipment operating are the fans, heater and the steam generator no dehumidifier. 73. It should be double-pane, well-insulated with low emissivity (low-E). This is because it needs to be dried to a lower moisture content than wood will air dry to outdoors. My aim was to develop a small dehumidification kiln for better control of the three key components of lumber drying: temperature, airflow and humidity. End baffles are also a good idea to prevent airflow from bypassing the stack entirely. Hardwood kiln drying schedules typically keep the dry bulb temperature below 80 C (176 F). I then manually rotate the fan boxes halfway through the drying cycle. A variety of wood drying kiln technologies exist today: conventional, dehumidification, solar, vacuum and radio frequency. In contrast, a dehumidification kiln uses a sealed chamber, with only enough energy input to maintain the desired temperature. The starter blocks should be as long as the stack is wide. Air drying to 6 - 8% MC is a very long term proposition and I'm not a patient man so I wanted a means to finish dry lumber after air drying outside to the EMC of my area of around 12 - 14%. 1. a furnace or oven for burning, baking, or drying, especially one for calcining lime or firing pottery. For a kiln temperature of 140 F, sterilization takes three to five hours. If you cannot find exact match, look at SG of same family species. -. (Note: This letter designation is related to the green MC of the species. This can create internal stress in the lumber that is released when sawing. Each layer adds approximately .81 R value. Moisture content step schedules can be converted to schedules based on time once a kiln operator develops a data record from at least 6 different kiln runs with lumber of the same thickness and species. Vacuum Kiln Drying. This can create internal stress in the lumber that is released when sawing. The stickers are uniform in size and usually 3/4 or 1 square. As you can recycle . Dehumidification Kilns Select a heater with an adjustable thermostat and a tip-over shutoff. Take a moisture reading in the end grain with a pin-type moisture meter or remote probe.) However, the natural light and ventilation offered by a small window outweighs any disadvantages. When the operating conditions of this option are followed the material will meet the requirements of being kiln dried (KD) and heat treated . A kiln schedule is a set of temperatures and humidities that are used during kiln operation. are generally kiln dried by time scheduleswhether the wood is intended for struc-tural lumber or for appearance uses, such as furniture or millwork. 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. From contributor D: . Wood-Mizer dehumidification and solar wood kilns range from 300 to 35,000 board feet capacity for drying lumber. Enter the email address you signed up with and we'll email you a reset link. This limits the amount of energy needed to bring lumber to the desired 6% to 8% moisture content. If the temperature is below this range, I start the heater and adjust the thermostat accordingly. Our next kiln charge is scheduled to begin around February 6, 2023. Be sure that all of the kiln equipment is working prop-erly before lumber is loaded into the kiln. Can also be used on any mobile device! H6`2}s=n:l)CR>/"\ Difficult-to-dry species might not exceed 60 C (140 F). Moisture Content Dry Bulb Wet Bulb Depression percent degree F degree F degree F Above 50 110 106 4 50 to 40 110 105 5 40 to 35 110 102 8 35 to 30 110 96 14 30 to 25 120 90 30 For the sterilization phase, air temperature needs to be around 140 F, for three to five hours. This slows the end-grain drying and limits the severity of end checking. Dehumidification kilns are similar to other kilns in basic construction and drying times are usually comparable. I decided on a dehumidification kiln after reading an article in Fine Woodworking (1991). Please refer to Appendix A which shows the Lumber Dry Kiln Bill of Materials. Frequently, the lumber has already air-dried for several years in a barn or outbuilding. My baffles hang from T-bar assemblies mounted to the ceiling. My shed kiln was stick-built from standard building material, and sized to take advantage of typical 4 x 8 sheet goods. . temperature. I know mixed loads are taboo, but this one worked well, other than the horse chestnut. I have sensors in the kiln for moisture levels & probes in the center of the wood attached to a lignomat moisture meter. They are easy to use and give you precision control over your drying. 2. After two days operating only the fans and DH, I take note of the temperature. Difficult-to-dry species might not exceed 140 degrees F. Dehumidification kilns are very . A locked padlock Kiln Structure . Whether to Wax Walnut Ends Before Steaming, Frequently Asked Questions about Widebelt Sanders. Not bragging or anything! 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. These kilns will typically hold several thousand board foot of lumber. The cost associated with shed construction was similar to buying a prefabricated kit. With a well-designed dehumidification kiln, hardwood lumber can be dried for mere pennies per board foot. hbbd``b` $ &UD\q@u The starter blocks should be as long as the stack is wide. November 1, 2020. Any info or advice on using dehumidification equipment to dry out chainsaw milled lumber. Ciencia y Tecnologia, Duygu Kocaefe, Ayhan Aytin, The Bolivian secondary forest products industry has experienced substantial growth during the last 10 years.

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