Initially, I set the DH to 40% RH, because I dont want to remove moisture too quickly. Although dehumidification kilns are slower than conventional kilns for drying, the lower drying temperature has the reported advantage of less degrade and less shrinkage. I prefer to empty the water tray manually and record the volume of water collected. Take a moisture reading in the end grain with a pin-type moisture meter or remote probe.) I then manually rotate the fan boxes halfway through the drying cycle. The starter blocks should be as long as the stack is wide. This would allow a stack of lumber four feet wide and 10 feet long. In addition, weight on top of the stack can be helpful, but nothing replaces baffles for the best lumber yield. Website Content Copyright 2023 Nyle Systems |. A higher humidity setting will run the unit sporadically to maintain that RH. The MC ranges are chosen so that the loss of the first one-third of moisture, and the highest risk of checking and staining, will occur in the first step listed.). - Model L300, L500, L1200-S Series - Medium Dehumidification Dry. Phytosanitary heat treatments of Ceratocystis lukuohia and Ceratocystis huliohia-colonized Metrosideros polymorpha wood were evaluated using kilns. 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. An official website of the United States government. In larger kilns, the heater may be needed in the latter part of the drying cycle. Joining end grain to long grain forms the king of joints. In vacuum kiln trials, logs were heated to 56C at 70 percent log radius depth and the temperature maintained for . In the majority of cases, the drying schedules are from the world literature, with emphasis on U.S., Canadian, and British publications. . 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. Wood drying (also seasoning lumber or wood seasoning) reduces the moisture content of wood before its use. For single-stack kilns, stationary fans are adequate. 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. Both restrained and control boards were dried to approximately 9 percent moisture content, representative of final in-service condi- tions. Unfortunately, little information is available regarding lumber drying technology and practices used, which is essential for the formulation of improvement strategies. I recommend a 2 x 3 sliding window with bug screen. A lock ( 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. A household dehumidifier (DH) removes moisture from the kiln chamber. 5. It is a good idea to sterilize the lumber at the end of the kiln run. Rocky Mountain . Place a 1x6 board on the floor behind the stack, tilted to a 45 angle. A pre-hung steel exterior door is ideal in this situation, because it offers weatherstripping and is fully insulated. Wood poles subjected to a 22- to 34-day dehumidification kiln schedule with a heat treatment to 60C to the poles' core. At the end of the cycle I have the opposite problem. 0000003109 00000 n 1998. by Dr. Eugene Wengert. My four main baffles consist of sheets of 1" Styrofoam insulation. The T-bars are made from 1/2 galvanized pipe and are attached to the rafters with threaded pipe flanges. 0000000710 00000 n Abstract. Operates at a temperature range from 80F - 160F (26 - 71C). With two-stack and three stack kilns, it is better to have reversible fans to alter the direction of airflow mid-cycle. Equalizing and conditioning are required for almost all hardwood 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. This report contains suggested dry kiln schedules for over 500 commercial woods, both temperate and tropical. Commercial scale steam kilns consume large amounts of energy. Created and Presented by: Henco Viljoen and Elijah McCarty with Nyle Dry Kilns. endstream endobj 283 0 obj <>/Metadata 40 0 R/OCProperties<>/OCGs[294 0 R]>>/Outlines 53 0 R/PageLayout/SinglePage/Pages 280 0 R/StructTreeRoot 72 0 R/Type/Catalog>> endobj 284 0 obj <>/Font<>/Properties<>/XObject<>>>/Rotate 0/StructParents 0/Tabs/S/Type/Page>> endobj 285 0 obj <>stream . 9. 282 0 obj <> endobj This can create internal stress in the lumber that is released when sawing. Drying small amounts of lumber using a dehumidification kiln is a suitable option for woodworkers even with limited knowledge of kilns. I modified one of the Radio Shack combo units so it could measure the RH remotely as well as the temp. the Dry Kiln Operator's Manual (Simpson, 1991). At the planer mill, warped 2 by 4's represent a significant loss in value. For international returns, please click here. 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 << An Overview. (Sawing and Drying Forum) 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 . Should a Moulding Mill Bring Sawmill Operations In-House? The thinner the stock, the more critical sticker placement becomes. This helps keep the lumber straight during the drying cycle; in fact, improper placement of stickers can permanently deform lumber. If the temperature is below this range, I start the heater and adjust the thermostat accordingly. 0000002536 00000 n 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. Dehumidification Kiln Drying. Temps are in Celsius (20C = 70F, 40C = 105F). Schedules. On the last load of lumber I purchased, I saved $2.50 per board foot compared to retail prices for kiln-dried lumber. From contributor D: The last thing to do before starting the kiln is to close the gable vent with an insulated cover. The kiln humidity can be expressed as an EMC, relative humidity, or wet-bulb temperature. In this paper, the effective schedules were further investigated for longer culm parts treated with boron. The kiln schedule information in the tables below has been assembled from many different sources, including drying texts and industrial contacts. I hope that the sawyer coated the ends of the lumber with Anchor-Seal or oil-based paint when it was green. For a kiln temperature of 140 F, sterilization takes three to five hours. My number one priority was to build a kiln that was easy to load and easy to monitor. 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). To condition the lumber, I introduce steam into the kiln for about two hours. Measure airflow over the stacks of lumber in various locations. You won't ever have the fastest kiln in town, but it can still work. 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. Staff. Dehumidification Kiln. But kiln drying may also introduce internal stresses into the woodparticularly if an improper kiln schedule is used, . I made a simple frame from plywood strips and attached the insulation sheets to them with screws and fender washers. After seven to 10 days, I reverse the fan direction to make sure all stacks of lumber dry evenly. 301 0 obj <>stream For the sterilization phase, air temperature needs to be around 140 F, for three to five hours. Difficult-to-dry species might not exceed 140 degrees F. Dehumidification kilns are very . Sticker spacing can be increased to 24" apart for 5/4 or thicker hardwood. BE CAREFUL--The first temperature value must be repeated for every MC class (column #2) that is above 30% MC. However, if you kiln dry hardwood lumber that has already been air dried, the process is much more forgiving. The thinner the stock, the more critical sticker placement becomes. The cost associated with shed construction was similar to buying a prefabricated kit. I can show you the kiln schedules and data. 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.) If your lumber stack is built on starter blocks, you will need to limit airflow there as well. For a single-stack kiln I recommend a minimum shed size of 8 x 12. Built properly, a shed kiln may even increase the value of a property. Equalizing and Conditioning Electrical requirements for a DIY kiln are pretty straightforward, but hiring an electrician is still a good idea. Also, for that approach to work, the chamber needs to be air tight. Academia.edu no longer supports Internet Explorer. If the temperature is below this range, I start the heater and adjust the thermostat accordingly. Select 3/4" conduit brackets for hanging baffles on 1/2" galvanized pipe. /Subtype /Image What can you do to speed up drying time? Kiln Drying . 1998. A kiln schedule is a set of temperatures and humidities that are used during kiln operation. To accommodate the floor insulation, blocking between joists is oriented horizontally instead of the normal vertical position. Heres a classic project that both steps up and provides overflow seating. For a kiln temperature of 140 F, sterilization takes three to five hours. Windows and doors are also sealed, as well as any holes cut for electrical service. Take a moisture reading in the end grain with a pin-type moisture meter or remote probe. Dehumidification kiln schedules 145 Sterilizing, equalizing, and conditioning treatments 145 Sterilizing treatments 145 Mold 145 Fungal stain and decay 146 . Check your local building codes for regionally specific requirements and electrical permits. %PDF-1.6 % Place a sticker at each end, and every 16 along the stack for 4/4 stock. Without baffles, the top layers of lumber experience potato chipping with cupping, twisting or warping. I hope that the sawyer coated the ends of the lumber with Anchor-Seal or oil-based paint when it was green. With each load I did not have the initial relative humidity rate. I found that brackets for mounting rigid metal electrical conduit work best. The sheetrock also helps to protect the fiberglass insulation. The problems with solar kilns include limited control over temperature and limited solar exposure, depending on your region and site location. For example, if you dry 7,500BF of fast drying Pine, you'd select the 8MBF chamber with the HT18 . This returns some moisture to the very dry exterior of the lumber, while not affecting the core moisture level. Omitting the sterilization phase can lead to costly losses from insect damage, so dont skip it. If you cannot find exact match, look at SG of same family species. A.gov website belongs to an official government Excel Program for Modeling Lumber Dry Kiln Operations - a model for lumber dry kiln operation. txN.a!HQ)FmCw~{B1Aq_!+zN#+j This makes lightweight baffles that can be easily moved and repositioned. JavaScript seems to be disabled in your browser. noun. Each layer of lumber is separated from the next by a series of stickers or spacer sticks. A 1.5-kW dehumidifier was installed in the solar dryer to determine the performance of a combined solar-dehumidification dryer. This allows for a more gentle kiln schedule to fully dry the timber. 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%. Changes in kiln temperatures and humidities are based on the MC of the lumber being dried, which in turn is determined from properly prepared kiln samples. Each layer of lumber is separated from the next by a series of "stickers" or spacer sticks. The schedules are all moisture content based, using the moisture content of the wettest half of the kiln samples. This is because it needs to be dried to a lower moisture content than wood will air dry to outdoors. Secure .gov websites use HTTPS Another great option is to convert an existing shed or outbuilding to a lumber kiln. Case hardening is a defect caused by the outer portion of a board drying quickly, while the inner portion dries more slowly. Maderas. Another common sticker size is 1 x 2, and these work fine as well. These figures hold true for lumber up to 2 thick. HDE small kilns feature all-aluminum construction for a long, maintenance-free life span . In time schedules, dry- and wet . . You can achieve top-quality results with incredible efficiency. In this system, moist air is not vented out of the kiln but is dehumidified, then recirculated . 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. After two days operating only the fans and DH, I take note of the temperature. Place some sample boards in the stack that will be easy to pull out for moisture testing later. Consider not only the space for the lumber stacks, but extra floor space to easily load and monitor the charge of lumber. Once the core readings are 6% to 8% on a fresh cut, the lumber is dry and ready for sterilization. Omitting the sterilization phase can lead to costly losses from insect damage, so don't skip it. Air speed of 350 feet per minute is appropriate for common hardwoods such as oak and maple. Hardwood lumber kiln drying schedules typically keep the dry bulb temperature below 180 F (82 C). Bring your moisture meter to confirm. 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Made in China, it exudes the classic style of Asian and Chinese cultures, featuring a unique shape that sets it apart from traditional jars. Our approach was to build and operate a small dehumidification dry kiln. 6 0 obj Corrosion resistant epoxy coated aluminum cabinets and specially coated dehumidification coils for an extra long life. A free BASIC program to convert the designations into actual temperatures and humidities is available from the author. The air flow rate through your stacks should be about 350FPM. endstream endobj startxref Sorry, preview is currently unavailable. . If it isn't overheating, it is leaking. Vote. kiln/. 0 Sears Canada 70 Pint Dehumidifier. November 1, 2020. Kiln schedules are completely assembled and written out for easy use. squares, handle stock, gunstock blanks) are given for many species. I cannot stress the importance of baffles enough. The kiln operator sets the kiln controls based on the initial moisture of the lumber as it is loaded into the kiln. A small electric heater supplies auxiliary heat to maintain adequate kiln temperature. Dehumidification drying system. Place some sample boards in the stack that will be easy to pull out for moisture testing later. temperature. I like these starter blocks to raise the lumber a few inches off the floor. Once all the lumber is stacked and stickered, place baffles over the lumber. The KD150 Dehumidification Kiln Kit is a compact, entry-level dehumidification kiln for drying lumber between 300 and 1000 board feet. For all kiln drying schedules, a heater should be used to sterilize the lumber and kill any insects that may be present. The company's small kilns can be configured for drying lumber, firewood, or heat-treating lumber or wood packaging. Basically the idea seems to be to maintain a constant temperature, and . If MC readings still arent at the desired range, the heat may need to be increased for the remainder of the drying cycle. 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. You can download the paper by clicking the button above. Chinese, Korean or Japanese kilns have an arch roof. I usually see a large volume of water in the DH each night when I check the kiln. Schedules Dry Kiln Schedules for Commercial Woods The last step requires a short period of high humidity to relieve the drying stresses in the boards. The store will not work correctly in the case when cookies are disabled. Enter the email address you signed up with and we'll email you a reset link. USDA, 1991) . In Fig. The velocity through the load is assumed to be between 275 and . Question Drying lumber too quickly can lead to deep end checking, warping and case hardening. Remove samples from the stack, and cut an inch or two off one end. Kiln drying is almost always essential for wood intended for interior uses. These well-known dehumidification kiln packages have been among our bestselling products for the past 30 years. To browse Academia.edu and the wider internet faster and more securely, please take a few seconds toupgrade your browser. 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. Recently, either Wood, or American Woodworker showed how to build a small version of a solar kiln. A lower RH setting will call for the DH to run more often. Whether to Wax Walnut Ends Before Steaming, Frequently Asked Questions about Widebelt Sanders. Reply. Many regions have increased the shed and outbuilding maximum allowable size without need for a permit. There are two main reasons for drying wood: Woodworking When wood is used as a construction material, whether as a structural support in a building . 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. /Length 7 0 R 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.