Most species of hardwood lumber can be safely dried this way, once the moisture content is 20% to 25% or less. Align the stickers over the starter blocks on the first course. I have sensors in the kiln for moisture levels & probes in the center of the wood attached to a lignomat moisture meter. 0000000710 00000 n Once the core readings are 6% to 8% on a fresh cut, the lumber is dry and ready for sterilization. Then align each subsequent layer of stickers over the last. Kiln drying lumber is a simple, cost effective method recommended for anyone who wants to increase profits by selling dried lumber. Only the fans need electricity. Made in China, it exudes the classic style of Asian and Chinese cultures, featuring a unique shape that sets it apart from traditional jars. If you use a lot of lumber, and youre a decent hand at carpentry, a shed kiln will quickly pay for itself. 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. Make sure the total amp draw is well within the limit of your electrical circuit. The cost associated with shed construction was similar to buying a prefabricated kit. If the temperature is below this range, I start the heater and adjust the thermostat accordingly. Take a moisture reading in the end grain with a pin-type moisture meter or remote probe. Another common sticker size is 1 x 2, and these work fine as well. The column on the right I added part way through is the kiln's internal RH. This kicker board will help distribute the airflow more evenly through all layers of lumber. Drying lumber too quickly can lead to deep end checking, warping and case hardening. Kiln drying lumber is a simple, cost effective method recommended for anyone who wants to increase profits by selling dried lumber. For a kiln temperature of 140 F, sterilization takes three to five hours. In this research, a drying restraint system was evaluated as a means of warp reduction in 8- and 16-foot-long SYP lumber. Sears Canada 70 Pint Dehumidifier. My baffles hang from T-bar assemblies mounted to the ceiling. From contributor D: Featuring lower cost drying at speeds equal to gas & steam, these kilns are continuously exceeding industry standards and changing the game. The lumber was then measured for crook, bow, and twist. Maderas. The remaining width allows for a 36-wide door and space for your drying equipment. Lock << My four main baffles consist of sheets of 1" Styrofoam insulation. %PDF-1.6 % The DH is not needed at this time, as the lumber is already bone-dry. 1. a furnace or oven for burning, baking, or drying, especially one for calcining lime or firing pottery. Please refer to Appendix A which shows the Lumber Dry Kiln Bill of Materials. 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. Without baffles, the top layers of lumber experience "potato chipping" with cupping, twisting or warping. November 1, 2020. A lower RH setting will call for the DH to run more often. 3.24 solar-dehumidification drying kiln Thicker lumber like 5/4 or quartersawn lumber is naturally more stable. All of these products were purchased at a local home center, except the remote hygrometer/thermometer which was purchased at a local electronics store. Dr. Gene Wengert provides schedules for kiln drying hardwood lumber. Dehumidification kilns from Nyle Systems in Brewer, Maine. This serves a dual purpose of supporting the rigid foam insulation as well as stiffening the floor framing. This would allow a stack of lumber four feet wide and 10 feet long. Among the various sizes of southern yellow pine (SYP) dimension lumber, 2 by 4 is produced in the greatest volume. These figures hold true for lumber up to 2" thick. The store will not work correctly in the case when cookies are disabled. The first thing to consider when designing a shed kiln is size. This helps keep the lumber straight during the drying cycle; in fact, improper placement of stickers can permanently deform lumber. Difficult-to-dry species might not exceed 140 degrees F. Dehumidification kilns are very . 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. . It should be double-pane, well-insulated with low emissivity (low-E). Kiln schedules are completely assembled and written out for easy use. This makes lightweight baffles that can be easily moved and repositioned. They are easy to use and give you precision control over your drying. Willie Sandry is a furniture maker and a lumber kiln operator in Camas, Washington. endstream endobj startxref The baffles do not need insulating properties, and plywood would work just as well. Basically the idea seems to be to maintain a constant temperature, and . 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 . Changing the position of the doorway in various kiln setups helps provide the best access to the stacks of lumber. The kiln humidity can be expressed as an EMC, relative humidity, or wet-bulb temperature. Low Temperature Kiln Drying Systems (120F) 300BF - 4000BF Capacity . After four days, I decrease the RH setting on the DH to 30% and continue to run the fans. My kiln uses four ceiling-mounted fans, each rated for 1,600 CFM. If you dry 9,500BF of slower drying Oak, youd use the 10MBF chamber with the HT8 Dehumidifier. Excel Program for Modeling Lumber Dry Kiln Operations - a model for lumber dry kiln operation. -. My four main baffles consist of sheets of 1 Styrofoam insulation. This is because it needs to be dried to a lower moisture content than wood will air dry to outdoors. That purchase was an average deal, and one I dont consider a particular bargain. Size and placement of the access door are critical as well. With a 130 F kiln temperature, sterilization will take 10 to 12 hours (Dry Kiln Operators Manual, 1991). Job Opportunities and Woodworking Services, Dust Collection, Safety and Plant Operation. 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. 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. I dont think the same could be said for an old reefer truck converted into a kiln (no matter how well it dries lumber). Vacuum Kiln Drying. Dehumidification drying system. Determine the correct designation, such as T3-D2 for 4/4 red oak. A shed kiln has minimal venting (usually one or two gable vents) and sealed soffits. The DH is not needed at this time, as the lumber is already bone-dry. USDA, 1991) . This problem is magnified if the lumber is thin or flatsawn. 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. stream Wood-Mizer dehumidification and solar wood kilns range from 300 to 35,000 board feet capacity for drying lumber. Wood-Mizer dehumidification and solar wood kilns range from 300 to 35,000 board feet capacity for drying lumber. Also, since heat rises, ceiling-mounted fans have the added benefit of circulating the warmest air over the lumber. They are easy to use and give you precision control over your drying. 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. This returns some moisture to the very dry exterior of the lumber, while not affecting the core moisture level. After a short period of grumbling, they join me to lay down wood blocks for the first layer of lumber. Know how to choose and apply the correct schedule for the lumber. To hang the baffles, simply attach hooks to the plywood frame. txN.a!HQ)FmCw~{B1Aq_!+zN#+j This allows for a more gentle kiln schedule to fully dry the timber. Usually, you need anywhere between five to eight kiln schedules to complete the process. . A maximum 45 F depression often produces better lumber. The schedule designations use the popular U.S. Forest Products Laboratory designations. For the sterilization phase, air temperature needs to be around 140 F, for three to five hours. /Type /XObject In-service replacement of warped 2 by 4's as wall studs or truss members is costly. 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. For international returns, please click here. Vote. organization in the United States. Such temperatures are high enough to kill insectsanother advantage of kiln drying over air drying. My kiln schedule starts with running all fans and the dehumidifier for two days, measuring and removing water as it accumulates. A heavy-duty 1,500-watt space heater works fine. Among dimension lumber, the 2- by 4-inch size is typically the most susceptible to warp for a variety of reasons. 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. Heat comes primarily from an integral dehumidification unit that also removes . Remove samples from the stack, and cut an inch or two off one end. For sterilizing thicker lumber, additional time is required. This slows the end-grain drying and limits the severity of end checking. A variety of wood drying kiln technologies exist today: conventional, dehumidification, solar, vacuum and radio frequency. Extruded polystyrene foam (blue or pink rigid foam) in this thickness has an R value of 10. 0000004213 00000 n hb```[@9p(T-3jO:g)@S 4Y]g7l\V!c!$Bf J B@&xcEz8PH@ZHs1/X$qOq,x'x$0.rWg*d XAT10 );9 For a kiln temperature of 140 F, sterilization takes three to five hours. 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. 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. Madison, WI: U.S. Department of Agriculture, Forest Service, Forest Products Laboratory. You may also return purchases to a Rockler store near you for store credit. (116 C) temperature. Taking moisture away at the rate the board will "safely" part with it . 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. I prefer to empty the water tray manually and record the volume of water collected. %PDF-1.4 % 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 Take a moisture reading in the end grain with a pin-type moisture meter or remote probe.) At the end of the cycle I have the opposite problem. Case hardening is a defect caused by the outer portion of a board drying quickly, while the inner portion dries more slowly. This plan allows . If your lumber stack is built on starter blocks, you will need to limit airflow there as well. Looking at the cost-benefit analysis of a shed kiln can be enlightening. Staggering the seams between the sheathing and siding layers helps avoid air infiltration. Typical dehumidification kiln (FPL 1999 p. 12-10). 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 If severe enough, the lumber can develop honeycomb cracks throughout. You won't ever have the fastest kiln in town, but it can still work. Instead of using expensive electrically reversible fans designed for commercial kilns, I came up with a simple hardware solution. Over 40 years experience building kilns. Wood poles subjected to a 22- to 34-day dehumidification kiln schedule with a heat treatment to 60C to the poles' core. The kiln humidity can be expressed as an EMC, relative humidity, or wet-bulb temperature. Corners where walls meet should be sealed with expanding foam sealant. I'm trying to find a timetable or drying schedule for the basic dehumidification kilns you see on youtube. A free BASIC program to convert the designations into actual temperatures and humidities is available from the author. %%EOF Select a heater with an adjustable thermostat and a tip-over shutoff. 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 In vacuum kiln trials, logs were heated to 56C at 70 percent log radius depth and the temperature maintained for . Small, complete dehumidification dry kilns under 5,000 board-foot capacity are not available for sale. Another reason I like the idea of a shed kiln is the flexibility of future use. >> Abstract. Main thing is to not rush drying in first stages, as this will cause problems. Sorry, preview is currently unavailable. Solar kiln drying was most effective in the summer and early fall, when kiln efficiencies were 90% to 67%, respectively, and drying times were 2 to 3/one-half/ times faster than air drying. Loading the kiln begins by rousing my sons and letting them know Ive planned a day of work. If the temperature is below this range, I start the heater and adjust the thermostat accordingly. Low Temperature Kiln Drying Systems (120F), High Temperature Kiln Drying Systems (160F), Very High Temperature Kiln Drying Systems (220F), Website Content Copyright 2023 Nyle Systems |, Affordable and easy method to accomplish top quality lumber drying, Designed specifically for any sized operation, Modular based systems for unlimited capacity, No boiler or steam required with gas furnace, Can be installed along side existing kilns, Chambers are sized with our DH systems to meet your lumber drying requirements. Schedule for drying 4/4 and 5/4 upland red oak in a steam dry kiln. . A shed kiln is an attractive alternative for a couple of reasons. I hope that the sawyer coated the ends of the lumber with Anchor-Seal or oil-based paint when it was green. Temperatures inside the kiln range from 120 to 190 degrees F, depending on the stage of . After seven to 10 days, I reverse the fan direction to make sure all stacks of lumber dry evenly. Kiln Systems. For a single-stack kiln I recommend a minimum shed size of 8 x 12. 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. By. 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. 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.. T8-C3 or similar for hard maple), the article instead provided a table showing the "safe drying rates" (SDR) for a number of species. I am using a household . Academia.edu no longer supports Internet Explorer. Although I can maintain the 90 degree temperature, I could not start at the recommended humidity level unless I added humidity. They are based on different air flow rates, etc. On the last load of lumber I purchased, I saved $2.50 per board foot compared to retail prices for kiln-dried lumber. There may be more depression values than required; ignore the extra depression values in this table. Determine the equalization settings and conditioning settings, as required. For these items, please call the store where you purchased them or our customer service department at 1-800-376-7856 so we can assist you. This will allow the DH to drain automatically without you needing to enter the kiln. However, you may need more cycles depending on the species, moisture content, and size of the timber. With each load I did not have the initial relative humidity rate. I use a Rockler steam generator, item #42826 (www.rockler.com). 3.) Measure airflow over the stacks of lumber in various locations. The problems with solar kilns include limited control over temperature and limited solar exposure, depending on your region and site location. The fact is, most of my stacks of lumber air dry to 15% moisture content before entering the kiln. In contrast, a dehumidification kiln uses a sealed chamber, with only enough energy input to maintain the desired temperature. Sticker spacing can be increased to 24 apart for 5/4 or thicker hardwood. HWn8gXA N,[mKJr2"Ec9,t Dehumidification: This kiln-drying process requires the use of a heat pump system to remove water from the wood. This publication outlines the basic construction of a small scale dehumidification dry kiln. In smaller kilns, the heat generated by the fans and DH motor is sufficient to maintain temperatures in excess of 100 degrees. Subtract the wet-bulb depression from the dry-bulb temperatures for each schedule step and enter the value in the fifth column. Place some sample boards in the stack that will be easy to pull out for moisture testing later. 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. Leave an air space between the rigid foam and subfloor for additional insulating properties. Contractors work on a tight schedule, and that may not allow much time for curing and drying concrete. This prevents dead spots inside the chamber that experience limited airflow. (I have found that remotely monitoring the temperature and humidity with a WiFi sensor can be very helpful. Kiln dried wood typically sells for a third more than green lumber and eliminates the need for customers to incur costs associated with drying lumber . I selected a 36 outswing exterior door. With advances in spray foam insulation, it may be possible to seal older, drafty structures as well. . After two days operating only the fans and DH, I take note of the temperature. 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The conversion method described in the Dry Kiln Operator's Manual is not really accurate, but it is safe. Place a sticker at each end, and every 16" along the stack for 4/4 stock. 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. With a 130 F kiln temperature, sterilization will take 10 to 12 hours (Dry Kiln Operators Manual, 1991). Staff. 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. But kiln drying may also introduce internal stresses into the woodparticularly if an improper kiln schedule is used, . If MC readings still arent at the desired range, the heat may need to be increased for the remainder of the drying cycle. If your lumber stack is built on starter blocks, you will need to limit airflow there as well. I am removing water about 50% below the SDR. kiln/. A better choice might be a solar kiln, as you can dry wood from "wet" to 6-8 percent MC in 6-8 weeks. Construction of a kiln chamber is very similar to building a small house. Rep. FPL-GTR-57. H6`2}s=n:l)CR>/"\ You could use the dehumidifier to dry wood but it would not be part of a "kiln." Just be a different process. A 1.5-kW dehumidifier was installed in the solar dryer to determine the performance of a combined solar-dehumidification dryer. An anemometer confirms that your effort constructing baffles was worthwhile. January 27, 2007. By setting the relative humidity (RH) on the dehumidifier, you can control how often it runs. I usually see a large volume of water in the DH each night when I check the kiln. My question focuses on the initial relative humidity featured in the Safe Drying Rate table. The thinner the stock, the more critical sticker placement becomes. Equalizing and Conditioning This listing incorporates current market requirements for the various species, as well as the current quality of the lumber resource itself. Drying small amounts of lumber using a dehumidification kiln is a suitable option for woodworkers even with limited knowledge of kilns. (Sawing and Drying Forum) My number one priority was to build a kiln that was easy to load and easy to monitor. The KD150 Dehumidification Kiln Kit is a compact, entry-level dehumidification kiln for drying lumber between 300 and 1000 board feet. During the conditioning process, the only equipment operating are the fans, heater and the steam generator no dehumidifier. Also check that air isnt escaping around the side baffles or under the stack of lumber. This slows the end-grain drying and limits the severity of end checking. I had these custom cut and I air dried them outside under a tarp for 6 to 18 months (depending on which load they came in on) and then I kiln dried them in a Nyle dehumidification kiln for 3 months. If 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. This gives me a secondary method of tracking the drying process, using both water volume and moisture content (MC) readings. Once all the lumber is stacked and stickered, place baffles over the lumber. 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. 1. Air speed of 350 feet per minute is appropriate for common hardwoods such as oak and maple. After two days operating only the fans and DH, I take note of the temperature. Consider not only the space for the lumber stacks, but extra floor space to easily load and monitor the charge of lumber.