dehumidification kiln drying schedules dehumidification kiln drying schedules

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%. Willie Sandry is a furniture maker and a lumber kiln operator in Camas, Washington. Determine the correct designation, such as T3-D2 for 4/4 red oak. The last thing to do before starting the kiln is to close the gable vent with an insulated cover. kiln/. 0000004213 00000 n Instead of using expensive electrically reversible fans designed for commercial kilns, I came up with a simple hardware solution. Another reason I like the idea of a shed kiln is the flexibility of future use. Oregon-based HDE Dry Kilns has launched a new line of small kilns ranging from 2,000 to 12,000 board feet. 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.) Heat comes primarily from an integral dehumidification unit that also removes . For these reasons, I feel it is best to let the shed breathe, and forgo a plastic vapor barrier. 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's Manual (Simpson, 1991). The DH is not needed at this time, as the lumber is already bone-dry. 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. If it isn't overheating, it is leaking. I made a simple frame from plywood strips and attached theinsulation sheets to them with screws and fender washers. Wood-Mizer dehumidification and solar wood kilns range from 300 to 35,000 board feet capacity for drying lumber. There may be more depression values than required; ignore the extra depression values in this table. noun. The stickers are uniform in size and usually 3/4" or 1" square. Basically, you dont want all of the air rushing out under the stack, so find a way to redirect it. Sign In Upload. Thicker lumber like 5/4 or quartersawn lumber is naturally more stable. Use the gridded drawings provided on the PDF, Woodworking | Blog | Videos | Plans | How To. Commercial scale steam kilns consume large amounts of energy. Always use adequate samples representing both the wettest and driest lumber in the dryer. This limits the amount of energy needed to bring lumber to the desired 6% to 8% moisture content. Place some sample boards in the stack that will be easy to pull out for moisture testing later. Hardwood lumber kiln drying schedules typically keep the dry bulb temperature below 180 F (82 C). Among the various sizes of southern yellow pine (SYP) dimension lumber, 2 by 4 is produced in the greatest volume. Total costs for the materials were $2,704 based on 2006 prices. A 1.5-kW dehumidifier was installed in the solar dryer to determine the performance of a combined solar-dehumidification dryer. 3. In the third column, write down the appropriate dry-bulb temperatures. For the sterilization phase, air temperature needs to be around 140 F, for three to five hours. You won't ever have the fastest kiln in town, but it can still work. 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. temperature. We are proud of the quality of our products, and we stand behind them 100%. The store will not work correctly in the case when cookies are disabled. I find that unplugging the DH is helpful during the sterilization phase so I can add a second heater, without overwhelming my electrical circuit. Share. Schedule for drying 4/4 and 5/4 upland red oak in a steam dry kiln. The KD150 Dehumidification Kiln Kit is a compact, entry-level dehumidification kiln for drying lumber between 300 and 1000 board feet. 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 . This prevents "dead spots" inside the chamber that experience limited airflow. I like these "starter blocks" to raise the lumber a few inches off the floor. Place some sample boards in the stack that will be easy to pull out for moisture testing later. I like these starter blocks to raise the lumber a few inches off the floor. Insulation for walls and ceilings should be a minimum of R13. I have sensors in the kiln for moisture levels & probes in the center of the wood attached to a lignomat moisture meter. MC values in the kiln schedules are based on the wettest half of the kiln samples. Reply. The order was 540 board feet (BF) of 5/4 white oak. I'm trying to find a timetable or drying schedule for the basic dehumidification kilns you see on youtube. %3.3 Corners where walls meet should be sealed with expanding foam sealant. A discussion of how to apply "safe drying rate" calibrations with a home-built dehumidifying kiln. 6. 1998. 1998. by Dr. Eugene Wengert. However, you may need more cycles depending on the species, moisture content, and size of the timber. Created and Presented by: Henco Viljoen and Elijah McCarty with Nyle Dry Kilns. I found that brackets for mounting rigid metal electrical conduit work best. Although I can maintain the 90 degree temperature, I could not start at the recommended humidity level unless I added humidity. 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. )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. Align the stickers over the starter blocks on the first course. Academia.edu no longer supports Internet Explorer. Wood Shrink/Swell estimator - A web-based program to estimate shrink/ swell in wood. 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. This gives me a secondary method of tracking the drying process, using both water volume and moisture content (MC) readings. 1. It should be double-pane, well-insulated with low emissivity (low-E). The moisture loss, drying time and drying defects were determined. The common lumber name is used throughout. Sorry, preview is currently unavailable. You can achieve top-quality results with incredible efficiency. Enter the email address you signed up with and we'll email you a reset link. With two-stack and three stack kilns, it is better to have reversible fans to alter the direction of airflow mid-cycle. Adjust the baffles or fan direction to achieve good airflow. I cannot stress the importance of baffles enough. Delete from my manuals. Reweigh and obtain the oven dry weight. This shed will be essentially unheated for much of the year and very hot during the kiln-drying cycles. >> . Air speed of 350 feet per minute is appropriate for common hardwoods such as oak and maple. A higher humidity setting will run the unit sporadically to maintain that RH. For a kiln temperature of 140 F, sterilization takes three to five hours. Dr. Gene Wengert provides schedules for kiln drying hardwood lumber. Many regions have increased the shed and outbuilding maximum allowable size without need for a permit. _0e`bd\ p@ /Type /XObject This problem is magnified if the lumber is thin or flatsawn. T8-C3 or similar for hard maple), the article instead provided a table showing the "safe drying rates" (SDR) for a number of species. Size and placement of the access door are critical as well. The last step requires a short period of high humidity to relieve the drying stresses in the boards. Staggering the seams between the sheathing and siding layers helps avoid air infiltration. Each layer of lumber is separated from the next by a series of "stickers" or spacer sticks. In-service replacement of warped 2 by 4's as wall studs or truss members is costly. They are easy to use and give you precision control over your drying. Initially, I set the DH to 40% RH, because I dont want to remove moisture too quickly. Once the lumber is sterilized, it is ready for the conditioning phase. For example, if you dry 7,500BF of fast drying Pine, youd select the 8MBF chamber with the HT18 Dehumidifier. Then align each subsequent layer of stickers over the last. After four days, I decrease the RH setting on the DH to 30% and continue to run the fans. -. 0000001208 00000 n Different species should not be loaded simultaneously into the kiln due to often differing kiln schedules. You could use the dehumidifier to dry wood but it would not be part of a "kiln." Just be a different process. Electrical requirements for a DIY kiln are pretty straightforward, but hiring an electrician is still a good idea. If MC readings still arent at the desired range, the heat may need to be increased for the remainder of the drying cycle. Standard kiln drying temperatures are low - around 120 degrees Fahrenheit or so, and drying times vary by wood size and moisture level. However, because wood from stream With advances in spray foam insulation, it may be possible to seal older, drafty structures as well. Kiln dried wood typically sells for a third more than green lumber and eliminates the need for . Our capacities are 4,000 board feet in a kiln . I can show you the kiln schedules and data. Leave an air space between the rigid foam and subfloor for additional insulating properties. In Fig. Take a moisture reading in the end grain with a pin-type moisture meter or remote probe.) In smaller kilns, the heat generated by the fans and DH motor is sufficient to maintain temperatures in excess of 100 degrees. This returns some moisture to the very dry exterior of the lumber, while not affecting the core moisture level. Vote. 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. /BitsPerComponent 1 In addition, weight on top of the stack can be helpful, but nothing replaces baffles for the best lumber yield. The T-bars are made from 1/2" galvanized pipe and are attached to the rafters with threaded pipe flanges. This kicker board will help distribute the airflow more evenly through all layers of lumber. Soon the DH wont show much water collected in the tray. /Name /ImagePart_0 /Height 2587 We proudly stand behind all of our products. Without baffles, the top layers of lumber experience potato chipping with cupping, twisting or warping. To condition the lumber, I introduce steam into the kiln for about two hours. Using a piece of paper with 6 columns, write down the Schedule Step numbers in the first column on the left. (I have found that remotely monitoring the temperature and humidity with a WiFi sensor can be very helpful. 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. A free BASIC program to convert the designations into actual temperatures and humidities is available from the author. In the majority of cases, the drying schedules are from the world literature, with emphasis on U.S., Canadian, and British publications. The kiln climate is controlled by venting the hot air and replacing it with ambient air. The kiln humidity can be expressed as an EMC, relative humidity, or wet-bulb temperature. This can create internal stress in the lumber that is released when sawing. 0000001186 00000 n Over 40 years experience building kilns. I decided on a dehumidification kiln after reading an article in Fine Woodworking (1991). Wood-Mizer dehumidification and solar wood kilns range from 300 to 35,000 board feet capacity for drying lumber. Kiln drying lumber is a simple, cost effective method recommended for anyone who wants to increase profits by selling dried lumber. An anemometer confirms that your effort constructing baffles was worthwhile. To browse Academia.edu and the wider internet faster and more securely, please take a few seconds toupgrade your browser. Regardless of size, allow for a 36 door that opens to a hallway of open space. /Subtype /Image This plan allows . Remote operation and networking is optional. For DH kilns, use the same RH, but lower the temperature to the typical operating temperature for the compressor; raise temperature to steam values when convenient and possible. The T-bars are made from 1/2 galvanized pipe and are attached to the rafters with threaded pipe flanges. 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. Heres a classic project that both steps up and provides overflow seating. 9. Thus, a drying program can be adapted according to the characteristics of the kiln load, e.g., species, dimensions, and moisture content. A lower RH setting will call for the DH to run more often. In vacuum kiln trials, logs were heated to 56C at 70 percent log radius depth and the temperature maintained for . When that is the case, I know Ill have usable lumber in just a few weeks. Do not know just how the end point of moisture would compare. I either use some cedar 3 x 5, or 4 x 4 stock. The column on the right I added part way through is the kiln's internal RH. 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. . (Dry Kiln Operator's Manual. My kiln uses four ceiling-mounted fans, each rated for 1,600 CFM. The stickers are uniform in size and usually 3/4 or 1 square. The delicate blue and white color scheme c These kilns will typically hold several thousand board foot of lumber. A variety of wood drying kiln technologies exist today: conventional, dehumidification, solar, vacuum and radio frequency. In exchange for building the shed myself, I wound up with a shed of higher quality, with more features. %%EOF I either use some cedar 3" x 5", or 4" x 4" stock. A lower RH setting will call for the DH to run more often. I use a Rockler steam generator. noun: kiln; plural noun: kilns. Another common sticker size is 1" x 2", and these work fine as well. 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. In a professional DH kiln, the final climate for oak is 120F and <40>t over-dry it at that rate. These figures hold true for lumber up to 2 thick. Hardwood lumber kiln drying schedules typically keep the dry bulb temperature below 180 F (82 C). Kiln Structure . Any info or advice on using dehumidification equipment to dry out chainsaw milled lumber. /Filter /JBIG2Decode The kiln schedule information in the tables below has been assembled from many different sources, including drying texts and industrial contacts. If you dry 9,500BF of slower drying Oak, youd use the 10MBF chamber with the HT8 Dehumidifier. Appendix B . Another great option is to convert an existing shed or outbuilding to a lumber kiln. 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. 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. Adjust the baffles or fan direction to achieve good airflow. of this publication is to make available to dry kiln operators and others interested in kiln-drying wood, kiln schedules that are completely assembled and written out for ready reference and easy use. Loading the kiln begins by rousing my sons and letting them know Ive planned a day of work. . If severe enough, the lumber can develop honeycomb cracks throughout. Perhaps the best part: you wont need to calculate your lumber needs down to the board foot. 158 p. Dry kiln schedules for commercial woods : temperate and tropical. Moisture Content Dry Bulb Wet Bulb Depression percent degree F degree F degree F Above 50 110 106 4 50 to 40 110 105 5 40 to 35 110 102 8 35 to 30 110 96 14 30 to 25 120 90 30 For single-stack kilns, stationary fans are adequate. 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. I chose double wall construction with 1/2 sheathing, and 1/2 T1-11 siding. . %PDF-1.4 % 4. These well-known dehumidification kiln packages have been among our bestselling products for the past 30 years. A heavy-duty 1,500-watt space heater works fine. The problems with solar kilns include limited control over temperature and limited solar exposure, depending on your region and site location. Case hardening is a defect caused by the outer portion of a board drying quickly, while the inner portion dries more slowly. Equalizing and conditioning are required for almost all hardwood lumber. Windows and doors are also sealed, as well as any holes cut for electrical service. Its a nice use of technology and adds a measure of safety as well.) 5. 3, a simplified transverse section of a kiln chamber with an energy recovery and dehumidification system is shown. 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. There might be a problem with that if the chamber overheats and has to be vented because some water will leave that way. Two-by-four material sawn from young trees, thinnings, and stem tops contains a significant proportion of juvenile wood and is particularly notorious for warp. This makes lightweight baffles that can be easily moved and repositioned. Without baffles, the top layers of lumber experience "potato chipping" with cupping, twisting or warping. Dr. Gene Wengert provides schedules for kiln drying hardwood lumber. Take the electronics out of the kiln, and continue operating the heater and fans during this phase. My kiln schedule starts with running all fans and the dehumidifier for two days, measuring and removing water as it accumulates. End baffles are also a good idea to prevent airflow from bypassing the stack entirely. Job Opportunities and Woodworking Services, Dust Collection, Safety and Plant Operation. Using a Kiln Schedule All of these products were purchased at a local home center, except the remote hygrometer/thermometer which was purchased at a local electronics store. %PDF-1.6 % The four charges of lumber ranged from 600 to 700 board feet (bf), and a woodworker with no dry-kiln experience operated the kiln. building the dehumidification dry kiln. 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 Featuring lower cost drying at speeds equal to gas & steam, these kilns are continuously exceeding industry standards and changing the game. Difficult-to-dry species might not exceed 60 C (140 F). Wood drying (also seasoning lumber or wood seasoning) reduces the moisture content of wood before its use. Place a sticker at each end, and every 16" along the stack for 4/4 stock. 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). I've been drying hardwood lumber in this Sauno dehumidification kiln for 4 years with excellent results. - Model L300, L500, L1200-S Series - Medium Dehumidification Dry. This publication outlines the basic construction of a small scale dehumidification dry kiln. Difficult-to-dry species might not exceed 140 degrees F. Dehumidification kilns are very . Installing a window in a kiln may seem counterintuitive at first, because windows lose more heat than an insulated wall. During the conditioning process, the only equipment operating are the fans, heater and the steam generator no dehumidifier. My aim was to develop a small dehumidification kiln for better control of the three key components of lumber drying: temperature, airflow and humidity. To hang the baffles, simply attach hooks to the plywood frame. Kiln schedules are completely assembled and written out for easy use. I know mixed loads are taboo, but this one worked well, other than the horse chestnut. Abstract. 0000006274 00000 n Additionally, I have been underwhelmed by the performance of solar-operated fans. Typical . An anemometer confirms that your effort constructing baffles was worthwhile. Remove samples from the stack, and cut an inch or two off one end. I prefer to empty the water tray manually and record the volume of water collected. After four days, I decrease the RH setting on the DH to 30% and continue to run the fans. They are based on different air flow rates, etc. My question focuses on the initial relative humidity featured in the Safe Drying Rate table. HDE small kilns feature all-aluminum construction for a long, maintenance-free life span . 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. These figures hold true for lumber up to 2" thick. I often buy from sawyers or homeowners at 40% to 50% of retail price. 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. As a result, the kiln schedules were too severe. 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. The four charges of lumber ranged from 600 to 700 board feet (bf), and a woodworker with no dry-kiln experience operated the kiln. So, with that lengthy introduction, here is my question. This serves a dual purpose of supporting the rigid foam insulation as well as stiffening the floor framing. 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. I also wrapped the shed with Tyvek HomeWrap. Once all the lumber is stacked and stickered, place baffles over the lumber. The cost associated with shed construction was similar to buying a prefabricated kit. I am removing water about 50% below the SDR. are generally kiln dried by time scheduleswhether the wood is intended for struc-tural lumber or for appearance uses, such as furniture or millwork. Question The baffles direct airflow over and through the stack and prevent the top layers from drying too quickly. For a small scale shed kiln, I recommend a maximum footprint of 200 square feet. 0000000710 00000 n Gen. Tech. Case hardening is a defect caused by the outer portion of a board drying quickly, while the inner portion dries more slowly. The dry kiln operator is fully in control, with the ability to make changes as the dry kiln schedule is executing. In this research, a drying restraint system was evaluated as a means of warp reduction in 8- and 16-foot-long SYP lumber. A bead of silicone caulking between the subfloor and sill plate will prevent air infiltration. 0 This slows the end-grain drying and limits the severity of end checking. Dehumidification Kiln. Select 3/4" conduit brackets for hanging baffles on 1/2" galvanized pipe. 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. Most species of hardwood lumber can be safely dried this way, once the moisture content is 20% to 25% or less. 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. At the planer mill, warped 2 by 4's represent a significant loss in value. Madison, WI: U.S. Department of Agriculture, Forest Service, Forest Products Laboratory. For all kiln drying schedules, a heater should be used to sterilize the lumber and kill any insects that may be present. For the sterilization phase, air temperature needs to be around 140 F, for three to five hours. JavaScript seems to be disabled in your browser. Dehumidification dry kilns operate at lower drying temperatures (typically below 150F) than do conventional kilns, which results in longer drying schedules. Phytosanitary heat treatments of Ceratocystis lukuohia and Ceratocystis huliohia-colonized Metrosideros polymorpha wood were evaluated using kilns. Most species of hardwood lumber can be safely dried this way, once the moisture content is 20% to 25% or less. 4.4 drying schedule moisture content drying schedule . The last thing to do before starting the kiln is to close the gable vent with an insulated cover. Select 3/4 conduit brackets for hanging baffles on 1/2 galvanized pipe. An Overview. (Note: This letter designation is related to the green MC of the species. Looking at the cost-benefit analysis of a shed kiln can be enlightening. 3.) With each load I did not have the initial relative humidity rate. Lock Sears Canada 70 Pint Dehumidifier. Recently, either Wood, or American Woodworker showed how to build a small version of a solar kiln. Minus the drying equipment, a shed kiln is just an insulated storage space, with a host of possible uses. (I use the Mini-Ligno MD/C from Lignomat, www.lignomatusa.com.) If the fans and dehumidifer generate enough heat to maintain a temperature of 100 to 120 F, then I wont use the auxiliary heater. Basically, you don't want all of the air rushing out under the stack, so find a way to redirect it. Low Temperature Kiln Drying Systems (120F) 300BF - 4000BF Capacity . KD150 Series dehumidifier pdf manual download. Forum Responses Dehumidification Opportunities for Dehumidification Drying Of Hardwood Lumber Dimension Kiln Drying Hardwood Dimension Parts Discoloration Preventing Discolorations in Hardwood and Softwood Logs . Operates at a temperature range from 80F - 160F (26 - 71C). This report contains suggested dry kiln schedules for over 500 commercial woods, both temperate and tropical.