In smaller kilns, the heat generated by the fans and DH motor is sufficient to maintain temperatures in excess of 100 degrees. For all kiln drying schedules, a heater should be used to sterilize the lumber and kill any insects that may be present. There are two ways to remove water from the DH unit, and they both work well. Take the electronics out of the kiln, and continue operating the heater and fans during this phase. The last thing to do before starting the kiln is to close the gable vent with an insulated cover. 3, a simplified transverse section of a kiln chamber with an energy recovery and dehumidification system is shown. 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 . If the temperature is below this range, I start the heater and adjust the thermostat accordingly. Usually, you need anywhere between five to eight kiln schedules to complete the process. . 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%. Small, complete dehumidification dry kilns under 5,000 board-foot capacity are not available for sale. Academia.edu no longer supports Internet Explorer. ) or https:// means youve safely connected to the .gov website. The dry kiln operator is fully in control, with the ability to make changes as the dry kiln schedule is executing. 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 . If the interior volume of a kiln becomes too large, basic heaters and home dehumidifiers may be inadequate to control the kiln environment. Dehumidification Kilns This returns some moisture to the very dry exterior of the lumber, while not affecting the core moisture level. The schedules are all moisture content based, using the moisture content of the wettest half of the kiln samples. The baffles direct airflow over and through the stack and prevent the top layers from drying too quickly. %PDF-1.5 However, because wood from With two-stack and three stack kilns, it is better to have reversible fans to alter the direction of airflow mid-cycle. The thinner the stock, the more critical sticker placement becomes. squares, handle stock, gunstock blanks) are given for many species. With each load I did not have the initial relative humidity rate. 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. Formulating a Kiln Schedule Dehumidification drying system. End baffles are also a good idea to prevent airflow from bypassing the stack entirely. (I have found that remotely monitoring the temperature and humidity with a WiFi sensor can be very helpful. 0000001417 00000 n This kicker board will help distribute the airflow more evenly through all layers of lumber. Measure airflow over the stacks of lumber in various locations. Each layer of lumber is separated from the next by a series of stickers or spacer sticks. Our approach was to build and operate a small dehumidification dry kiln. Schedules. I have been reading & studying kiln schedules for years too. txN.a!HQ)FmCw~{B1Aq_!+zN#+j You can download the paper by clicking the button above. Dehumidification kilns from Nyle Systems in Brewer, Maine. Just walk out to the shed kiln and grab what you need from your custom-dried supply. Place a sticker at each end, and every 16" along the stack for 4/4 stock. are generally kiln dried by time scheduleswhether the wood is intended for struc-tural lumber or for appearance uses, such as furniture or millwork. 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 procedure is discussed in a following section. Sticker spacing can be increased to 24 apart for 5/4 or thicker hardwood. Culm parts with 2.0 and 2.2 m length after pressure treatment were dried in industrial kilns using three schedules with mild, severe and highly severe drying intensity. 0000001208 00000 n 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. Share. For end baffles, I use 2"-thick rigid foam insulation screwed to the main baffles. Subtract the wet-bulb depression from the dry-bulb temperatures for each schedule step and enter the value in the fifth column. However, you may need more cycles depending on the species, moisture content, and size of the timber. Oregon-based HDE Dry Kilns has launched a new line of small kilns ranging from 2,000 to 12,000 board feet. Remote operation and networking is optional. Measure airflow over the stacks of lumber in various locations. Take a moisture reading in the end grain with a pin-type moisture meter or remote probe.) A higher humidity setting will run the unit sporadically to maintain that RH. 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. Looking at the cost-benefit analysis of a shed kiln can be enlightening. Anyway, I included my log of a load I did in Nov '06 for everyone's amusement. If your lumber stack is built on starter blocks, you will need to limit airflow there as well. 6. A lower RH setting will call for the DH to run more often. Place a sticker at each end, and every 16 along the stack for 4/4 stock. The kiln climate is controlled by venting the hot air and replacing it with ambient air. Place a 1x6 board on the floor behind the stack, tilted to a 45 angle. A maximum 45 F depression often produces better lumber. Temperatures inside the kiln range from 120 to 190 degrees F, depending on the stage of . For all kiln drying schedules, a heater should be used to sterilize the lumber and kill any insects that may be present. Dehumidifier suggestion: http://amzn.to/2iYZqVZThis is the first in a series of videos showing how I built a kiln for drying lumber. A locked padlock Using a Kiln Schedule Enter the email address you signed up with and we'll email you a reset link. Nyle. My aim was to develop a small dehumidification kiln for better control of the three key components of lumber drying: temperature, airflow and humidity. The company's small kilns can be configured for drying lumber, firewood, or heat-treating lumber or wood packaging. -. 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. Loading the kiln begins by rousing my sons and letting them know Ive planned a day of work. (See the following sections for a discussion of how to develop a schedule from these designations.) This will allow the DH to drain automatically without you needing to enter the kiln. Regardless of size, allow for a 36 door that opens to a hallway of open space. %PDF-1.4 % Instead of using expensive electrically reversible fans designed for commercial kilns, I came up with a simple hardware solution. Dehumidification dry kilns operate at lower drying temperatures (typically below 150F) than do conventional kilns, which results in longer drying schedules. This will allow the heater to cycle on and off automatically, according to the kiln operators setting. Air speed of 350 feet per minute is appropriate for common hardwoods such as oak and maple. Delete from my manuals. After a short period of grumbling, they join me to lay down wood blocks for the first layer of lumber. Items shipped directly from the manufacturer cannot be returned in store. Enter the email address you signed up with and we'll email you a reset link. But kiln drying may also introduce internal stresses into the woodparticularly if an improper kiln schedule is used, . This makes lightweight baffles that can be easily moved and repositioned. Dehumidification: This kiln-drying process requires the use of a heat pump system to remove water from the wood. The delicate blue and white color scheme c 6 0 obj Do not know just how the end point of moisture would compare. Select 3/4" conduit brackets for hanging baffles on 1/2" galvanized pipe. 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? 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. For example, if you dry 7,500BF of fast drying Pine, youd select the 8MBF chamber with the HT18 Dehumidifier. Air speed of 350 feet per minute is appropriate for common hardwoods such as oak and maple. . Understand how kiln performance must be modified to permit the use of custom schedules for specific product applications; Be able to modify existing conventional kiln schedules to dry products in dehumidifier kilns; Recognize degrades common to various species, including hardwoods, and modify handling practices to minimize these For a small scale shed kiln, I recommend a maximum footprint of 200 square feet. What can you do to speed up drying time? If the fans and dehumidifer generate enough heat to maintain a temperature of 100 to 120 F, then I wont use the auxiliary heater. Ideally, a lumber kiln would be large enough to dry multiple stacks of lumber. Its a nice use of technology and adds a measure of safety as well.) An official website of the United States government. In larger kilns, the heater may be needed in the latter part of the drying cycle. Dehumidification Opportunities for Dehumidification Drying Of Hardwood Lumber Dimension Kiln Drying Hardwood Dimension Parts Discoloration Preventing Discolorations in Hardwood and Softwood Logs . 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.. . Schedules Dry Kiln Schedules for Commercial Woods Always use adequate samples representing both the wettest and driest lumber in the dryer. /Type /XObject Any info or advice on using dehumidification equipment to dry out chainsaw milled lumber. This shed will be essentially unheated for much of the year and very hot during the kiln-drying cycles. If severe enough, the lumber can develop honeycomb cracks throughout. After seven to 10 days, I reverse the fan direction to make sure all stacks of lumber dry evenly. Select 3/4 conduit brackets for hanging baffles on 1/2 galvanized pipe. 3. . A lazy Susan with 180 detents mounts the fan box to the ceiling. /Filter /JBIG2Decode 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. building the dehumidification dry kiln. For sterilizing thicker lumber, additional time is required. 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. With a 130 F kiln temperature, sterilization will take 10 to 12 hours (Dry Kiln Operators Manual, 1991). The fact is, most of my stacks of lumber air dry to 15% moisture content before entering the kiln. H6`2}s=n:l)CR>/"\ As you can recycle . In this system, moist air is not vented out of the kiln but is dehumidified, then recirculated . Also, for that approach to work, the chamber needs to be air tight. 1998. by Dr. Eugene Wengert. )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 kiln schedule information in the tables below has been assembled from many different sources, including drying texts and industrial contacts. In larger kilns, the heater may be needed in the latter part of the drying cycle. These kilns will typically hold several thousand board foot of lumber. In addition, wood can be dried by special methods that include solar drying (use of greenhouse-type dryers or those equipped with solar collectors . When that is the case, I know Ill have usable lumber in just a few weeks. Corrosion resistant epoxy coated aluminum cabinets and specially coated dehumidification coils for an extra long life. 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.) WOODWEB is a registered trademark of Woodweb.com. The T-bars are made from 1/2 galvanized pipe and are attached to the rafters with threaded pipe flanges. I then manually rotate the fan boxes halfway through the drying cycle. Electrical requirements for a DIY kiln are pretty straightforward, but hiring an electrician is still a good idea. 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. This kicker board will help distribute the airflow more evenly through all layers of lumber. Low temperatures can be used for an extra safety margin on greener lumber. For the best experience on our site, be sure to turn on Javascript in your browser. Go to the second number designation (the wet-bulb depression designation) and find the corresponding depressions in the table below. To condition the lumber, I introduce steam into the kiln for about two hours. Soon the DH wont show much water collected in the tray. I prefer to empty the water tray manually and record the volume of water collected.