An official website of the United States government. 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). I'd like to know for my own curiosity, as well as to be able to generate SDR schedules for other species not given in the American Woodworker article, like the 6 foot long 24" wide slabs of 8/4 madrone I got this summer. (A major source was Dry Kiln Schedules for Commercial Woods which is available from the Forest Products Society in Madison, WI.) Without baffles, the top layers of lumber experience "potato chipping" with cupping, twisting or warping. 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. Also, since heat rises, ceiling-mounted fans have the added benefit of circulating the warmest air over the lumber. These are rough-saw red oak. I cannot stress the importance of baffles enough. With a 130 F kiln temperature, sterilization will take 10 to 12 hours ( Dry Kiln Operators Manual, 1991 ). We are proud of the quality of our products, and we stand behind them 100%. %3.3 These figures hold true for lumber up to 2 thick. Schedules for several thicknesses and specialty products (e.g. An Overview. Gen. Tech. My kiln schedule starts with running all fans and the dehumidifier for two days, measuring and removing water as it accumulates. Select a heater with an adjustable thermostat and a tip-over shutoff. Using a Kiln Schedule This returns some moisture to the very dry exterior of the lumber, while not affecting the core moisture level. 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. The Bolivian wood products industry was surveyed to determine lumber drying capacity, technology and. This prevents "dead spots" inside the chamber that experience limited airflow. We proudly stand behind all of our products. (116 C) temperature. Exterior sheathing and siding type also factors into the heat-holding ability of the structure. kiln/. Q,kjifT33P[! 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. This can be done by heating above 133F for 4 hours (measured at the core of the wood), or at 120F for about 7 - 10 days. I then manually rotate the fan boxes halfway through the drying cycle. Commercial scale steam kilns consume large amounts of energy. 8. 158 p. Dry kiln schedules for commercial woods : temperate and tropical. My kiln uses four ceiling-mounted fans, each rated for 1,600 CFM. Add up the amp draw on all the equipment you plan to use in the kiln, including a heater, dehumidifier, fans and steam generator. I found that brackets for mounting rigid metal electrical conduit work best. This, of course, is gross savings; we must calculate electrical costs to determine the net savings: in this case, about $62. Select 3/4" conduit brackets for hanging baffles on 1/2" galvanized pipe. Add to my manuals. Excel Program for Modeling Lumber Dry Kiln Operations - a model for lumber dry kiln operation. 0 Each layer adds approximately .81 R value. The four charges of lumber ranged from 600 to 700 board feet (bf), and a woodworker with no dry-kiln experience operated the kiln. Wood Drying/ Seasoning. I modified one of the Radio Shack combo units so it could measure the RH remotely as well as the temp. To condition the lumber, I introduce steam into the kiln for about two hours. If the fans and dehumidifer generate enough heat to maintain a temperature of 100 to 120 F, then I wont use the auxiliary heater. organization in the United States. During the conditioning process, the only equipment operating are the fans, heater and the steam generator no dehumidifier. It should be double-pane, well-insulated with low emissivity (low-E). 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. 301 0 obj <>stream If the temperature is below this range, I start the heater and adjust the thermostat accordingly. A free BASIC program to convert the designations into actual temperatures and humidities is available from the author. The velocity through the load is assumed to be between 275 and . HT systems use 40-60% less energy than gas-fired or steam dry kilns. 9. When the operating conditions of this option are followed the material will meet the requirements of being kiln dried (KD) and heat treated . 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. Temps are in Celsius (20C = 70F, 40C = 105F). Corrosion resistant epoxy coated aluminum cabinets and specially coated dehumidification coils for an extra long life. My aim was to develop a small dehumidification kiln for better control of the three key components of lumber drying: temperature, airflow and humidity. noun. Thicker lumber like 5/4 or quartersawn lumber is naturally more stable. 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. The DH is not needed at this time, as the lumber is already bone-dry. This will allow the DH to drain automatically without you needing to enter the kiln. After two days operating only the fans and DH, I take note of the temperature. Consider the weight of the lumber that will be placed in the structure and fortify the building accordingly. Table 1 shows a typical drying schedule for sugar maple. I prefer to empty the water tray manually and record the volume of water collected. Once the lumber is sterilized, it is ready for the conditioning phase. My kiln schedule starts with running all fans and the dehumidifier for two days, measuring and removing water as it accumulates. Check your local building codes for regionally specific requirements and electrical permits. Oregon-based HDE Dry Kilns has launched a new line of small kilns ranging from 2,000 to 12,000 board feet. Small, complete dehumidification dry kilns under 5,000 board-foot capacity are not available for sale. By. >> Then, write down the appropriate MC ranges (determined in #2 above) in the second column. Perhaps the best part: you wont need to calculate your lumber needs down to the board foot. To accommodate the floor insulation, blocking between joists is oriented horizontally instead of the normal vertical position. This will allow the heater to cycle on and off automatically, according to the kiln operator's setting. In this paper, the effective schedules were further investigated for longer culm parts treated with boron. %PDF-1.6 % For all kiln drying schedules, a heater should be used to sterilize the lumber and kill any insects that may be present. Detailed design and custom manufacture of dehumidification and chiller systems for food processing, lumber drying and industrial applications. are generally kiln dried by time scheduleswhether the wood is intended for struc-tural lumber or for appearance uses, such as furniture or millwork. - Model L300, L500, L1200-S Series - Medium Dehumidification Dry. It is a meaningless exercise to try to convert those schedules for the kiln you built. 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. Schedules Dry Kiln Schedules for Commercial Woods In the third column, write down the appropriate dry-bulb temperatures. My number one priority was to build a kiln that was easy to load and easy to monitor. Standard kiln drying temperatures are low - around 120 degrees Fahrenheit or so, and drying times vary by wood size and moisture level. Know how to choose and apply the correct schedule for the lumber. A pre-hung steel exterior door is ideal in this situation, because it offers weatherstripping and is fully insulated. These kilns will typically hold several thousand board foot of 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. The dry kiln operator is fully in control, with the ability to make changes as the dry kiln schedule is executing. Corners where walls meet should be sealed with expanding foam sealant. I am removing water about 50% below the SDR. Also, since heat rises, ceiling-mounted fans have the added benefit of circulating the warmest air over the lumber. If your lumber stack is built on starter blocks, you will need to limit airflow there as well. 0000001417 00000 n Our approach was to build and operate a small dehumidification dry kiln. For single-stack kilns, stationary fans are adequate. The kiln humidity can be expressed as an EMC, relative humidity, or wet-bulb temperature. Thus, a drying program can be adapted according to the characteristics of the kiln load, e.g., species, dimensions, and moisture content. A shed kiln has minimal venting (usually one or two gable vents) and sealed soffits. Use the gridded drawings provided on the PDF, Woodworking | Blog | Videos | Plans | How To. Both restrained and control boards were dried to approximately 9 percent moisture content, representative of final in-service condi- tions. Once the core readings are 6% to 8% on a fresh cut, the lumber is dry and ready for sterilization. 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. I decided on a dehumidification kiln after reading an article in Fine Woodworking (1991). Y}-m+'@DQ4\h8GP]y@ yL. 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. For a small scale shed kiln, I recommend a maximum footprint of 200 square feet. The schedules can also be formulated manually as follows. Only the fans need electricity. 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. Place a 16 board on the floor behind the stack, tilted to a 45 angle. 1. I was hoping someone could point me in the right direction or share experience. January 27, 2007. Dehumidification Kiln Drying. These figures hold true for lumber up to 2" thick. Operates at a temperature range from 80F - 160F (26 - 71C). I often buy from sawyers or homeowners at 40% to 50% of retail price. After four days, I decrease the RH setting on the DH to 30% and continue to run the fans. Wood-Mizer dehumidification and solar wood kilns range from 300 to 35,000 board feet capacity for drying lumber. Initially, I set the DH to 40% RH, because I dont want to remove moisture too quickly. A dehumidification kiln continuously recycles the heat throughout the chamber, rather than . Dr. Gene Wengert provides schedules for kiln drying hardwood lumber. Place a 1x6 board on the floor behind the stack, tilted to a 45 angle. /Filter /JBIG2Decode 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. (In the original Dry Kiln Operators Manual written in the early 1950s, some species were not used in high quality products. I find that unplugging the DH is helpful during the sterilization phase so I can add a second heater, without overwhelming my electrical circuit. 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. The company's small kilns can be configured for drying lumber, firewood, or heat-treating lumber or wood packaging. Kiln drying is usually preceded by air drying to bring the moisture content of the wood down below 30%. Leave an air space between the rigid foam and subfloor for additional insulating properties. Dehumidification kiln schedules 145 Sterilizing, equalizing, and conditioning treatments 145 Sterilizing treatments 145 Mold 145 Fungal stain and decay 146 . 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. _0e`bd\ p@ Omitting the sterilization phase can lead to costly losses from insect damage, so dont skip it. Built properly, a shed kiln may even increase the value of a property. Kiln drying normally involves temperatures in the range of 40-75 C (about 100-170 F). Basically, you dont want all of the air rushing out under the stack, so find a way to redirect it. As a result, the kiln schedules were too severe. Inexpensive Dehumidification KilnIn this video we'll build and load a 14' long 4' by 4' wood kiln that dries wood by heat and dehumidification.We had quite a. 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. If you cannot find exact match, look at SG of same family species. It uses a simple humidistat to control the dehumidifier, and a remote bulb thermostat to control the heater, which is a couple of light bulbs. A heavy-duty 1,500-watt space heater works fine. Figure 3-4 Drying Schedules Normal Schedule Alternate Schedule Moisture Content Dry Bulb Wet Bulb Dry Bulb Wet Bulb Group 2 Above 45% 90F 85F 100F 97F . This fact sheet summarizes the basics of kiln drying wood, the most commonly used methods, drying schedules and some drying defects. You may also return purchases to a Rockler store near you for store credit. Although I can maintain the 90 degree temperature, I could not start at the recommended humidity level unless I added humidity. The last thing to do before starting the kiln is to close the gable vent with an insulated cover. The common lumber name is used throughout. 3. 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. Difficult-to-dry species might not exceed 140 degrees F. Dehumidification kilns are very . Reweigh and obtain the oven dry weight. Loading the kiln begins by rousing my sons and letting them know Ive planned a day of work. The delicate blue and white color scheme c txN.a!HQ)FmCw~{B1Aq_!+zN#+j I know mixed loads are taboo, but this one worked well, other than the horse chestnut. 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. Also check that air isnt escaping around the side baffles or under the stack of lumber. Additionally, a 12 air plenum is required between the walls and stacks of lumber. In this research, a drying restraint system was evaluated as a means of warp reduction in 8- and 16-foot-long SYP lumber. A household dehumidifier (DH) removes moisture from the kiln chamber. I know your kiln is absolutely tight and perfectly sealed, but it has to vent some or it would overheat. Place a sticker at each end, and every 16 along the stack for 4/4 stock. A variety of wood drying kiln technologies exist today: conventional, dehumidification, solar, vacuum and radio frequency. A higher humidity setting will run the unit sporadically to maintain that RH. 282 0 obj <> endobj 0000006297 00000 n This is because it needs to be dried to a lower moisture content than wood will air dry to outdoors. This can create internal stress in the lumber that is released when sawing. This can create internal stress in the lumber that is released when sawing. Madison, WI: U.S. Department of Agriculture, Forest Service, Forest Products Laboratory. For a kiln temperature of 140 F, sterilization takes three to five hours. Subtract the wet-bulb depression from the dry-bulb temperatures for each schedule step and enter the value in the fifth column. End baffles are also a good idea to prevent airflow from bypassing the stack entirely. Each layer of lumber is separated from the next by a series of stickers or spacer sticks. 7. Wood drying (also seasoning lumber or wood seasoning) reduces the moisture content of wood before its use. Low temperatures can be used for an extra safety margin on greener lumber. A bead of silicone caulking between the subfloor and sill plate will prevent air infiltration. Attic fans are a perfect way to provide airflow over the stacks of lumber. Please refer to Appendix A which shows the Lumber Dry Kiln Bill of Materials. %PDF-1.5 A Checklist for Operators of Small Dry Kilns A companion to A Start-up Guide for Operators of Small Dry Kilns (FOR-132) Terry Conners, Forestry and Natural Resources These well-known dehumidification kiln packages have been among our bestselling products for the past 30 years. This helps keep the lumber straight during the drying cycle; in fact, improper placement of stickers can permanently deform lumber. 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. the Dry Kiln Operator's Manual (Simpson, 1991). This kicker board will help distribute the airflow more evenly through all layers of lumber. 4.4 drying schedule moisture content drying schedule . Sign In Upload. A lower RH setting will call for the DH to run more often. With advances in spray foam insulation, it may be possible to seal older, drafty structures as well. The schedules are all moisture content based, using the moisture content of the wettest half of the kiln samples. This will allow the heater to cycle on and off automatically, according to the kiln operators setting. Among the various sizes of southern yellow pine (SYP) dimension lumber, 2 by 4 is produced in the greatest volume. Rep. FPL-GTR-57. 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.) I either use some cedar 3 x 5, or 4 x 4 stock. %%EOF You can achieve top-quality results with incredible efficiency. With a 130 F kiln temperature, sterilization will take 10 to 12 hours (Dry Kiln Operators Manual, 1991). Bring your moisture meter to confirm. A 1.5-kW dehumidifier was installed in the solar dryer to determine the performance of a combined solar-dehumidification dryer. 6. There are two ways to remove water from the DH unit, and they both work well. Dr. Gene Wengert provides schedules for kiln drying hardwood lumber. 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. hTn8>_l7h.&E:Bem=C9n\8]lMPc. Regardless of size, allow for a 36 door that opens to a hallway of open space. 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. 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. H6`2}s=n:l)CR>/"\ For the best experience on our site, be sure to turn on Javascript in your browser. Instead of using expensive electrically reversible fans designed for commercial kilns, I came up with a simple hardware solution. Official websites use .gov In addition, weight on top of the stack can be helpful, but nothing replaces baffles for the best lumber yield. For the sterilization phase, air temperature needs to be around 140 F, for three to five hours. Wood-Mizer dehumidification and solar wood kilns range from 300 to 35,000 board feet capacity for drying lumber. Initially, I set the DH to 40% RH, because I dont want to remove moisture too quickly. That purchase was an average deal, and one I dont consider a particular bargain. Basically the idea seems to be to maintain a constant temperature, and . However, the natural light and ventilation offered by a small window outweighs any disadvantages. When that is the case, I know Ill have usable lumber in just a few weeks. Joining end grain to long grain forms the king of joints. This publication outlines the basic construction of a small scale dehumidification dry kiln. 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. Kiln drying lumber is a simple, cost effective method recommended for anyone who wants to increase profits by selling dried lumber. I either use some cedar 3" x 5", or 4" x 4" stock. Once the flooring deck is constructed, think about sealing the shed framing at every opportunity. In contrast, a dehumidification kiln uses a sealed chamber, with only enough energy input to maintain the desired temperature. (I have found that remotely monitoring the temperature and humidity with a WiFi sensor can be very helpful. The sheetrock also helps to protect the fiberglass insulation. For sterilizing thicker lumber, additional time is required. Be sure that all of the kiln equipment is working prop-erly before lumber is loaded into the kiln. 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. Frequently, the lumber has already air-dried for several years in a barn or outbuilding. Also check that air isnt escaping around the side baffles or under the stack of lumber. Looking at the cost-benefit analysis of a shed kiln can be enlightening. For a kiln temperature of 140 F, sterilization takes three to five hours. I chose double wall construction with 1/2 sheathing, and 1/2 T1-11 siding. Another common sticker size is 1 x 2, and these work fine as well. After a short period of grumbling, they join me to lay down wood blocks for the first layer of lumber. The kiln climate is controlled by venting the hot air and replacing it with ambient air. If severe enough, the lumber can develop honeycomb cracks throughout. 0000003109 00000 n After four days, I decrease the RH setting on the DH to 30% and continue to run the fans. The air flow rate through your stacks should be about 350FPM. Can also be used on any mobile device! However, because wood from Soon the DH wont show much water collected in the tray. A lazy Susan with 180 detents mounts the fan box to the ceiling. Lay down the bead of caulking before raising the walls. If you use a lot of lumber, and youre a decent hand at carpentry, a shed kiln will quickly pay for itself. The baffles do not need insulating properties, and plywood would work just as well. A locked padlock Many available kiln designs require a large, heavy door. My four main baffles consist of sheets of 1 Styrofoam insulation. A heavy-duty 1,500-watt space heater works fine. Sticker spacing can be increased to 24 apart for 5/4 or thicker hardwood. Drying small amounts of lumber using a dehumidification kiln is a suitable option for woodworkers even with limited knowledge of kilns. They are normally mounted in the gable of household attics, and they are designed to be used in high temperature environments. Share sensitive information only on official, secure websites. %PDF-1.4 % Dont even think of powering your kiln with an extension cord. Place some sample boards in the stack that will be easy to pull out for moisture testing later. 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. 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 . A kiln schedule is a set of temperatures and humidities that are used during kiln operation. -. Particularly, important investment has taken place in lumber drying capacity. Temperatures inside the kiln range from 120 to 190 degrees F, depending on the stage of . Website Content Copyright 2023 Nyle Systems |. hb```[@9p(T-3jO:g)@S 4Y]g7l\V!c!$Bf J B@&xcEz8PH@ZHs1/X$qOq,x'x$0.rWg*d XAT10 );9 Low Temperature Kiln Drying Systems (120F) 300BF - 4000BF Capacity . The fact is, most of my stacks of lumber air dry to 15% moisture content before entering the kiln. Place a sticker at each end, and every 16" along the stack for 4/4 stock. But kiln drying may also introduce internal stresses into the woodparticularly if an improper kiln schedule is used, . A typical home center sheds floors are underbuilt for the weight of a load of lumber. endstream endobj startxref Case hardening is a defect caused by the outer portion of a board drying quickly, while the inner portion dries more slowly. Created and Presented by: Henco Viljoen and Elijah McCarty with Nyle Dry Kilns. With a 130 F kiln temperature, sterilization will take 10 to 12 hours ( Dry Kiln Operators Manual, 1991 ). This air space is absolutely critical for even airflow, so count on the extra floor space right from the design phase. At the end of the cycle I have the opposite problem. Featuring lower cost drying at speeds equal to gas & steam, these kilns are continuously exceeding industry standards and changing the game. The moisture loss, drying time and drying defects were determined. They are based on different air flow rates, etc. 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. . The stickers are uniform in size and usually 3/4" or 1" square. 0000001186 00000 n . (I use the Mini-Ligno MD/C from Lignomat, www.lignomatusa.com.) All of these products were purchased at a local home center, except the remote hygrometer/thermometer which was purchased at a local electronics store. Dehumidification: This kiln-drying process requires the use of a heat pump system to remove water from the wood. The DH is not needed at this time, as the lumber is already bone-dry. 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 Installing sheetrock and fire taping is a good idea for a heated room. You won't ever have the fastest kiln in town, but it can still work.
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