dehumidification kiln drying schedules

Kiln dried wood typically sells for a third more than green lumber and eliminates the need for . Excel Program for Modeling Lumber Dry Kiln Operations - a model for lumber dry kiln operation. Each layer adds approximately .81 R value. A 1.5-kW dehumidifier was installed in the solar dryer to determine the performance of a combined solar-dehumidification dryer. In addition, wood can be dried by special methods that include solar drying (use of greenhouse-type dryers or those equipped with solar collectors . 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. Anyway, I included my log of a load I did in Nov '06 for everyone's amusement. This helps keep the lumber straight during the drying cycle; in fact, improper placement of stickers can permanently deform lumber. Consider the weight of the lumber that will be placed in the structure and fortify the building accordingly. 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). 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. For all kiln drying schedules, a heater should be used to sterilize the lumber and kill any insects that may be present. For more capacity, consider a two stack kiln (12 x 12), or a three-stack kiln (12 x 16). A dehumidification kiln makes sense particularly when the lumber is air-dried first. With a 130 F kiln temperature, sterilization will take 10 to 12 hours ( Dry Kiln Operators Manual, 1991 ). - Model L300, L500, L1200-S Series - Medium Dehumidification Dry. If the fans and dehumidifer generate enough heat to maintain a temperature of 100 to 120 F, then I wont use the auxiliary heater. Dehumidifier suggestion: http://amzn.to/2iYZqVZThis is the first in a series of videos showing how I built a kiln for drying lumber. (Note: This letter designation is related to the green MC of the species. End baffles are also a good idea to prevent airflow from bypassing the stack entirely. txN.a!HQ)FmCw~{B1Aq_!+zN#+j 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. 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. Wood Drying/ Seasoning. Dehumidification kilns from Nyle Systems in Brewer, Maine. 2. Q,kjifT33P[! Go to the second letter designation (the MC Class Designation) and find the corresponding MC ranges in the table below. However, if you kiln dry hardwood lumber that has already been air dried, the process is much more forgiving. 4. Omitting the sterilization phase can lead to costly losses from insect damage, so don't skip it. 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 . In addition, weight on top of the stack can be helpful, but nothing replaces baffles for the best lumber yield. Unfortunately, little information is available regarding lumber drying technology and practices used, which is essential for the formulation of improvement strategies. A higher humidity setting will run the unit sporadically to maintain that RH. By. The approach described in the article where you try to keep the water leaving at a steady rate is fine. Please refer to Appendix A which shows the Lumber Dry Kiln Bill of Materials. I recommend a 2 x 3 sliding window with bug screen. The common lumber name is used throughout. This, of course, is gross savings; we must calculate electrical costs to determine the net savings: in this case, about $62. HDE small kilns feature all-aluminum construction for a long, maintenance-free life span . Both restrained and control boards were dried to approximately 9 percent moisture content, representative of final in-service condi- tions. A discussion of how to apply "safe drying rate" calibrations with a home-built dehumidifying kiln. 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. (116 C) temperature. -. WOODWEB is a registered trademark of Woodweb.com. For single-stack kilns, stationary fans are adequate. Air speed of 350 feet per minute is appropriate for common hardwoods such as oak and maple. Regardless of size, allow for a 36 door that opens to a hallway of open space. These figures hold true for lumber up to 2" thick. 301 0 obj <>stream 0000006297 00000 n Place a 16 board on the floor behind the stack, tilted to a 45 angle. There are many types of kilns, but the most common are dehumidification kilns and conventional kilns. 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. Diy dehumidifier kiln time table. I guess I am thinking that while I am seeing the wood's MC and the kiln's RH drop smoothly, the fact that the temperature jumps around a bit may mean that the drying rates are hard to control, hence my loss of horse chestnut. If you dry 9,500BF of slower drying Oak, youd use the 10MBF chamber with the HT8 Dehumidifier. A low temperature heat treatment chamber and/or dehumidification kiln is identified as operating between approximately 43C (110F) and 56C (133F) for an extended period during the kiln drying cycle. In larger kilns, the heater may be needed in the latter part of the drying cycle. This makes lightweight baffles that can be easily moved and repositioned. 0000001186 00000 n MC values in the kiln schedules are based on the wettest half of the kiln samples. 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. Basically, you don't want all of the air rushing out under the stack, so find a way to redirect it. On this order alone, I saved over $1,300 by drying the lumber myself. Maderas. 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? 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 . (I use the Mini-Ligno MD/C from Lignomat, www.lignomatusa.com.) Check your local building codes for regionally specific requirements and electrical permits. Dehumidification kilns are similar to other kilns in basic construction and drying times are usually comparable. During the conditioning process, the only equipment operating are the fans, heater and the steam generator no dehumidifier. . This kicker board will help distribute the airflow more evenly through all layers of lumber. You can download the paper by clicking the button above. A pre-hung steel exterior door is ideal in this situation, because it offers weatherstripping and is fully insulated. Once the core readings are 6% to 8% on a fresh cut, the lumber is dry and ready for sterilization. This fact sheet summarizes the basics of kiln drying wood, the most commonly used methods, drying schedules and some drying defects. Ciencia y Tecnologia, Duygu Kocaefe, Ayhan Aytin, The Bolivian secondary forest products industry has experienced substantial growth during the last 10 years. I have sensors in the kiln for moisture levels & probes in the center of the wood attached to a lignomat moisture meter. 0 \ HWn8gXA N,[mKJr2"Ec9,t After seven to 10 days, I reverse the fan direction to make sure all stacks of lumber dry evenly. Windows and doors are also sealed, as well as any holes cut for electrical service. Instead of using expensive electrically reversible fans designed for commercial kilns, I came up with a simple hardware solution. Reply. Staff. You won't ever have the fastest kiln in town, but it can still work. 3.) Sears Canada 70 Pint Dehumidifier. The DH is not needed at this time, as the lumber is already bone-dry. Typical . It is a good idea to sterilize the lumber at the end of the kiln run. I prefer to empty the water tray manually and record the volume of water collected. Delete from my manuals. 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 . In-service replacement of warped 2 by 4's as wall studs or truss members is costly. Our approach was to build and operate a small dehumidification dry kiln. This limits the amount of energy needed to bring lumber to the desired 6% to 8% moisture content. 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 Remove samples from the stack, and cut an inch or two off one end. Another common sticker size is 1 x 2, and these work fine as well. My baffles hang from T-bar assemblies mounted to the ceiling. The kiln schedule information in the tables below has been assembled from many different sources, including drying texts and industrial contacts. Once the lumber is sterilized, it is ready for the conditioning phase. In Fig. Among dimension lumber, the 2- by 4-inch size is typically the most susceptible to warp for a variety of reasons. Oregon-based HDE Dry Kilns has launched a new line of small kilns ranging from 2,000 to 12,000 board feet. This report contains suggested dry kiln schedules for over 500 commercial woods, both temperate and tropical. If you cannot find exact match, look at SG of same family species. endstream endobj startxref For example, if you dry 7,500BF of fast drying Pine, you'd select the 8MBF chamber with the HT18 . Schedules for several thicknesses and specialty products (e.g. 1. The last thing to do before starting the kiln is to close the gable vent with an insulated cover. In time schedules, dry- and wet . Make sure the total amp draw is well within the limit of your electrical circuit. A better choice might be a solar kiln, as you can dry wood from "wet" to 6-8 percent MC in 6-8 weeks. , , o* j=d Looking at the cost-benefit analysis of a shed kiln can be enlightening. T8-C3 or similar for hard maple), the article instead provided a table showing the "safe drying rates" (SDR) for a number of species. At the planer mill, warped 2 by 4's represent a significant loss in value. 282 0 obj <> endobj In smaller kilns, the heat generated by the fans and DH motor is sufficient to maintain temperatures in excess of 100 degrees. A small electric heater supplies auxiliary heat to maintain adequate kiln temperature. Dehumidification drying equipment is available, but an enclosure must be built to house the equipment and dry the lumber. Construction of a kiln chamber is very similar to building a small house. We proudly stand behind all of our products. Over 40 years experience building kilns. 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. /Filter /JBIG2Decode Adjust the baffles or fan direction to achieve good airflow. If required, look-up and write down the RH (sixth column) and EMC (seventh column) for each schedule step. 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 Basically, you dont want all of the air rushing out under the stack, so find a way to redirect it. Go to the second number designation (the wet-bulb depression designation) and find the corresponding depressions in the table below. I cannot stress the importance of baffles enough. If severe enough, the lumber can develop honeycomb cracks throughout. I use a Rockler steam generator. This makes lightweight baffles that can be easily moved and repositioned. /Length 7 0 R /Height 2587 Heres a classic project that both steps up and provides overflow seating. . I cannot stress the importance of baffles enough. The baffles do not need insulating properties, and plywood would work just as well. My kiln uses four ceiling-mounted fans, each rated for 1,600 CFM. Once all the lumber is stacked and stickered, place baffles over the lumber.

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