Share. A bead of silicone caulking between the subfloor and sill plate will prevent air infiltration. In larger kilns, the heater may be needed in the latter part of the drying cycle. hbbd``b` $ &UD\q@u Measure airflow over the stacks of lumber in various locations. Air speed of 350 feet per minute is appropriate for common hardwoods such as oak and maple. Abstract. A typical kiln schedule is a series of temperatures and relative humidities, which are applied at various stages of drying as can be seen in Table 1. . You can achieve top-quality results with incredible efficiency. The remaining width allows for a 36-wide door and space for your drying equipment. (Dry Kiln Operator's Manual. Corrosion resistant epoxy coated aluminum cabinets and specially coated dehumidification coils for an extra long life. ) or https:// means youve safely connected to the .gov website. Place a 16 board on the floor behind the stack, tilted to a 45 angle. 0000001186 00000 n 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. The common lumber name is used throughout. This can create internal stress in the lumber that is released when sawing. 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. Hardwood lumber kiln drying schedules typically keep the dry bulb temperature below 180 F (82 C). Table 1 shows a typical drying schedule for sugar maple. A kiln schedule is a set of temperatures and humidities that are used during kiln operation. It can be constructed in any style, with architectural features that match or complement an existing home. A shed kiln is an attractive alternative for a couple of reasons. I know your kiln is absolutely tight and perfectly sealed, but it has to vent some or it would overheat. %PDF-1.5 %%EOF Schedules for several thicknesses and specialty products (e.g. The first charge of mixed air-dried 4/4 hardwoods and softwoods was kiln-dried from 18.4% to 7.3% moisture content (MC) in 15 days with no . 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. It should be double-pane, well-insulated with low emissivity (low-E). This serves a dual purpose of supporting the rigid foam insulation as well as stiffening the floor framing. Sign In Upload. 301 0 obj <>stream Dehumidification kilns are similar to other kilns in basic construction and drying times are usually comparable. %PDF-1.4 % Exterior sheathing and siding type also factors into the heat-holding ability of the structure. Total costs for the materials were $2,704 based on 2006 prices. Created and Presented by: Henco Viljoen and Elijah McCarty with Nyle Dry Kilns. The fact is, most of my stacks of lumber air dry to 15% moisture content before entering the kiln. The order was 540 board feet (BF) of 5/4 white oak. Measure airflow over the stacks of lumber in various locations. Nyle Systems dehumidification kiln packages are our best known product with nearly unlimited drying capabilities. Oregon-based HDE Dry Kilns has launched a new line of small kilns ranging from 2,000 to 12,000 board feet. 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. To hang the baffles, simply attach hooks to the plywood frame. Determine the correct designation, such as T3-D2 for 4/4 red oak. There may be more depression values than required; ignore the extra depression values in this table. After four days, I decrease the RH setting on the DH to 30% and continue to run the fans. . That purchase was an average deal, and one I dont consider a particular bargain. I have constructed a kiln using these plans. But kiln drying may also introduce internal stresses into the woodparticularly if an improper kiln schedule is used, . Place some sample boards in the stack that will be easy to pull out for moisture testing later. Conventional kiln drying. For a single-stack kiln I recommend a minimum shed size of 8 x 12. Thicker lumber like 5/4 or quartersawn lumber is naturally more stable. I decided on a dehumidification kiln after reading an article in Fine Woodworking (1991). For example, if you dry 7,500BF of fast drying Pine, youd select the 8MBF chamber with the HT18 Dehumidifier. Corners where walls meet should be sealed with expanding foam sealant. Check your local building codes for regionally specific requirements and electrical permits. This plan allows . Kiln drying is the process of drying wood in a controlled environment, where temperature, air circulation and humidity are monitored and stabilized. Instead of using expensive electrically reversible fans designed for commercial kilns, I came up with a simple hardware solution. Ciencia y Tecnologia, Duygu Kocaefe, Ayhan Aytin, The Bolivian secondary forest products industry has experienced substantial growth during the last 10 years. 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. Go to the second number designation (the wet-bulb depression designation) and find the corresponding depressions in the table below. 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 John Baines Reply to Dann Barry 1 year ago My kiln uses four ceiling-mounted fans, each rated for 1,600 CFM. Ignoring for a moment the merits of a homebrew DH kiln versus a Nyle, I was curious to see that rather than referencing the standard kiln schedules (e.g. November 1, 2020. There are two ways to remove water from the DH unit, and they both work well. For single-stack kilns, stationary fans are adequate. A better choice might be a solar kiln, as you can dry wood from "wet" to 6-8 percent MC in 6-8 weeks. 0000006297 00000 n Always use adequate samples representing both the wettest and driest lumber in the dryer. I often buy from sawyers or homeowners at 40% to 50% of retail price. (Note: This letter designation is related to the green MC of the species. the Dry Kiln Operator's Manual (Simpson, 1991). Also, you can't really control well by measuring the collected water because some of the water leaks out with vented or leaking air. This helps keep the lumber straight during the drying cycle; in fact, improper placement of stickers can permanently deform lumber. Apply foil tape to the edges of the main baffles to help protect the Styrofoam. 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 . It is a good idea to sterilize the lumber at the end of the kiln run. Dr. Gene Wengert provides schedules for kiln drying hardwood lumber. This will allow the DH to drain automatically without you needing to enter the kiln. At the end of the cycle I have the opposite problem. 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. Typical dehumidification kiln (FPL 1999 p. 12-10). This shed will be essentially unheated for much of the year and very hot during the kiln-drying cycles. Kiln drying lumber is a simple, cost effective method recommended for anyone who wants to increase profits by selling dried lumber. You may also return purchases to a Rockler store near you for store credit. From contributor D: 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. Also, since heat rises, ceiling-mounted fans have the added benefit of circulating the warmest air over the lumber. The thinner the stock, the more critical sticker placement becomes. I cannot stress the importance of baffles enough. What can you do to speed up drying time? organization in the United States. 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.). A pre-hung steel exterior door is ideal in this situation, because it offers weatherstripping and is fully insulated. Dehumidification Kilns Also, for that approach to work, the chamber needs to be air tight. Select a heater with an adjustable thermostat and a tip-over shutoff. End baffles are also a good idea to prevent airflow from bypassing the stack entirely. In Fig. Among dimension lumber, the 2- by 4-inch size is typically the most susceptible to warp for a variety of reasons. Construction of a kiln chamber is very similar to building a small house. Also check that air isnt escaping around the side baffles or under the stack of lumber. I modified one of the Radio Shack combo units so it could measure the RH remotely as well as the temp. To browse Academia.edu and the wider internet faster and more securely, please take a few seconds toupgrade your browser. If your lumber stack is built on starter blocks, you will need to limit airflow there as well. Leave an air space between the rigid foam and subfloor for additional insulating properties. The fact is, most of my stacks of lumber air dry to 15% moisture content before entering the kiln. Wood poles subjected to a 22- to 34-day dehumidification kiln schedule with a heat treatment to 60C to the poles' core. I made a simple frame from plywood strips and attached the insulation sheets to them with screws and fender washers. 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%. 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. Go to the first number designation (the temperature designation) and find the corresponding temperatures in the table below. The first load was started with 60% and this load was started with 78%. Loading the kiln begins by rousing my sons and letting them know Ive planned a day of work. 1. My number one priority was to build a kiln that was easy to load and easy to monitor. The kiln humidity can be expressed as an EMC, relative humidity, or wet-bulb temperature. Lock For the best experience on our site, be sure to turn on Javascript in your browser. 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. 2. End baffles are also a good idea to prevent airflow from bypassing the stack entirely. Minus the drying equipment, a shed kiln is just an insulated storage space, with a host of possible uses. The baffles direct airflow over and through the stack and prevent the top layers from drying too quickly. Willie Sandry is a furniture maker and a lumber kiln operator in Camas, Washington. I recently picked up a back issue of American Woodworker, #94 June 2002, that has a good article on constructing a simple DH kiln. My aim was to develop a small dehumidification kiln for better control of the three key components of lumber drying: temperature, airflow and humidity. )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. A typical home center sheds floors are underbuilt for the weight of a load of lumber. Kiln Structure . This problem is magnified if the lumber is thin or flatsawn. This will allow the heater to cycle on and off automatically, according to the kiln operators setting. January 27, 2007. When the operating conditions of this option are followed the material will meet the requirements of being kiln dried (KD) and heat treated . Drying small amounts of lumber using a dehumidification kiln is a suitable option for woodworkers even with limited knowledge of kilns. I was hoping someone could point me in the right direction or share experience. 10. By. Another reason I like the idea of a shed kiln is the flexibility of future use. If MC readings still arent at the desired range, the heat may need to be increased for the remainder of the drying cycle. 6. Also, since heat rises, ceiling-mounted fans have the added benefit of circulating the warmest air over the lumber. 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. I usually see a large volume of water in the DH each night when I check the kiln. Joining end grain to long grain forms the king of joints. KD150 Series dehumidifier pdf manual download. The four charges of lumber ranged from 600 to 700 board feet (bf), and a woodworker with no dry-kiln experience operated the kiln. Place some sample boards in the stack that will be easy to pull out for moisture testing later. This gives me a secondary method of tracking the drying process, using both water volume and moisture content (MC) readings. In this research, a drying restraint system was evaluated as a means of warp reduction in 8- and 16-foot-long SYP lumber. The starter blocks should be as long as the stack is wide. If it isn't overheating, it is leaking. They are based on different air flow rates, etc. Recently, either Wood, or American Woodworker showed how to build a small version of a solar kiln. (I use the Mini-Ligno MD/C from Lignomat, www.lignomatusa.com.) This would allow a stack of lumber four feet wide and 10 feet long. A lazy Susan with 180 detents mounts the fan box to the ceiling. Can also be used on any mobile device! Loading the kiln begins by rousing my sons and letting them know Ive planned a day of work. Vote. kiln/. Such temperatures are high enough to kill insectsanother advantage of kiln drying over air drying. It is a meaningless exercise to try to convert those schedules for the kiln you built. They are normally mounted in the gable of household attics, and they are designed to be used in high temperature environments. 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 Forum Responses Do not know just how the end point of moisture would compare. This publication outlines the basic construction of a small scale dehumidification dry kiln. Khmer Kiln: quite similar to the Anagama kiln however, traditional Khmer Kilns had a flat roof. Bring your moisture meter to confirm. Kiln Drying . Take a moisture reading in the end grain with a pin-type moisture meter or remote probe. I opted not to install a true vapor barrier between the framing and sheetrock, because of potential condensation and mold issues with sheds constructed this way. To hang the baffles, simply attach hooks to the plywood frame. This listing incorporates current market requirements for the various species, as well as the current quality of the lumber resource itself. A 1.5-kW dehumidifier was installed in the solar dryer to determine the performance of a combined solar-dehumidification dryer. Take a moisture reading in the end grain with a pin-type moisture meter or remote probe.) On this order alone, I saved over $1,300 by drying the lumber myself. A lower RH setting will call for the DH to run more often. For a kiln temperature of 140 F, sterilization takes three to five hours. We proudly stand behind all of our products. A dehumidification kiln makes sense particularly when the lumber is air-dried first. However, if you kiln dry hardwood lumber that has already been air dried, the process is much more forgiving. The kiln schedule information in the tables below has been assembled from many different sources, including drying texts and industrial contacts. Determine the equalization settings and conditioning settings, as required. However, you may need more cycles depending on the species, moisture content, and size of the timber. (Sawing and Drying Forum) Official websites use .gov 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. Please refer to Appendix A which shows the Lumber Dry Kiln Bill of Materials. Equalizing and Conditioning This air space is absolutely critical for even airflow, so count on the extra floor space right from the design phase. -. With a 130 F kiln temperature, sterilization will take 10 to 12 hours ( Dry Kiln Operators Manual, 1991 ). Once the core readings are 6% to 8% on a fresh cut, the lumber is dry and ready for sterilization. The cost associated with shed construction was similar to buying a prefabricated kit. I made a simple frame from plywood strips and attached theinsulation sheets to them with screws and fender washers. 0 \ Its a nice use of technology and adds a measure of safety as well.) For the sterilization phase, air temperature needs to be around 140 F, for three to five hours. Align the stickers over the starter blocks on the first course. A small electric heater supplies auxiliary heat to maintain adequate kiln temperature. Made in China, it exudes the classic style of Asian and Chinese cultures, featuring a unique shape that sets it apart from traditional jars. Maderas. 282 0 obj <> endobj I find that unplugging the DH is helpful during the sterilization phase so I can add a second heater, without overwhelming my electrical circuit. Installing sheetrock and fire taping is a good idea for a heated room. Low temperatures can be used for an extra safety margin on greener lumber. I find that unplugging the DH is helpful during the sterilization phase so I can add a second heater, without overwhelming my electrical circuit. Instead of using expensive electrically reversible fans designed for commercial kilns, I came up with a simple hardware solution. Nyle. In the majority of cases, the drying schedules are from the world literature, with emphasis on U.S., Canadian, and British publications. Dehumidification Opportunities for Dehumidification Drying Of Hardwood Lumber Dimension Kiln Drying Hardwood Dimension Parts Discoloration Preventing Discolorations in Hardwood and Softwood Logs . Dehumidification Kilns These figures hold true for lumber up to 2" thick. Both restrained and control boards were dried to approximately 9 percent moisture content, representative of final in-service condi- tions. An Overview. This prevents "dead spots" inside the chamber that experience limited airflow. Although I can maintain the 90 degree temperature, I could not start at the recommended humidity level unless I added humidity. I then manually rotate the fan boxes halfway through the drying cycle. Seems like a pretty simple way to run the kiln - once or twice a day just measure the amount of water extracted, and turn down the humidity a bit as needed. Hardwood kiln drying schedules typically keep the dry bulb temperature below 80 C (176 F). Place a sticker at each end, and every 16 along the stack for 4/4 stock. Omitting the sterilization phase can lead to costly losses from insect damage, so dont skip it. If MC readings still arent at the desired range, the heat may need to be increased for the remainder of the drying cycle. Among the various sizes of southern yellow pine (SYP) dimension lumber, 2 by 4 is produced in the greatest volume. Over 40 years experience building kilns. The velocity through the load is assumed to be between 275 and . Basically the idea seems to be to maintain a constant temperature, and . Remove samples from the stack, and cut an inch or two off one end. Most species of hardwood lumber can be safely dried this way, once the moisture content is 20% to 25% or less. Operates at a temperature range from 80F - 160F (26 - 71C). During the conditioning process, the only equipment operating are the fans, heater and the steam generator no dehumidifier. HWn8gXA N,[mKJr2"Ec9,t This makes lightweight baffles that can be easily moved and repositioned. If severe enough, the lumber can develop honeycomb cracks throughout. My four main baffles consist of sheets of 1" Styrofoam insulation. Know how to choose and apply the correct schedule for the lumber. Without baffles, the top layers of lumber experience "potato chipping" with cupping, twisting or warping. Our capacities are 4,000 board feet in a kiln . I like these "starter blocks" to raise the lumber a few inches off the floor. Electrical requirements for a DIY kiln are pretty straightforward, but hiring an electrician is still a good idea. are generally kiln dried by time scheduleswhether the wood is intended for struc-tural lumber or for appearance uses, such as furniture or millwork. For end baffles, I use 2-thick rigid foam insulation screwed to the main baffles. After seven to 10 days, I reverse the fan direction to make sure all stacks of lumber dry evenly. With two-stack and three stack kilns, it is better to have reversible fans to alter the direction of airflow mid-cycle. The kiln process involves the drying of wood in a chamber where air circulation, relative humidity and temperature can be controlled so that the moisture content of wood can be reduced to a target . In this system, moist air is not vented out of the kiln but is dehumidified, then recirculated . By setting the relative humidity (RH) on the dehumidifier, you can control how often it runs. >> This can create internal stress in the lumber that is released when sawing. All of these products were purchased at a local home center, except the remote hygrometer/thermometer which was purchased at a local electronics store. . An anemometer confirms that your effort constructing baffles was worthwhile. Regardless of size, allow for a 36 door that opens to a hallway of open space. Staff. in the kiln to dry specific wood products at a satisfactory rate without causing objectionable drying defects. My question focuses on the initial relative humidity featured in the Safe Drying Rate table. The following tables show some examples of oak schedules for steam dry kilns and dehumidification dryers. This slows the end-grain drying and limits the severity of end checking. These well-known dehumidification kiln packages have been among our bestselling products for the past 30 years. Kiln dried wood typically sells for a third more than green lumber and eliminates the need for . Consider the weight of the lumber that will be placed in the structure and fortify the building accordingly. Basically, you don't want all of the air rushing out under the stack, so find a way to redirect it. Remote operation and networking is optional. This, of course, is gross savings; we must calculate electrical costs to determine the net savings: in this case, about $62. For a kiln temperature of 140 F, sterilization takes three to five hours. 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. Question A lower RH setting will call for the DH to run more often. The lumber was then measured for crook, bow, and twist. Unfortunately, little information is available regarding lumber drying technology and practices used, which is essential for the formulation of improvement strategies. I usually see a large volume of water in the DH each night when I check the kiln. Delete from my manuals. Many regions have increased the shed and outbuilding maximum allowable size without need for a permit. Check out More On the Web for my complete calculations to figure savings. Adjust the baffles or fan direction to achieve good airflow. So, with that lengthy introduction, here is my question. Additionally, I have been underwhelmed by the performance of solar-operated fans. If your lumber stack is built on starter blocks, you will need to limit airflow there as well. With a 130 F kiln temperature, sterilization will take 10 to 12 hours ( Dry Kiln Operators Manual, 1991 ). Schedules Dry Kiln Schedules for Commercial Woods Any small building could work, as long as it has a minimum of 2 x 4 framing, and will seal out unwanted air. I cannot stress the importance of baffles enough. 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. The last step requires a short period of high humidity to relieve the drying stresses in the boards. Place a 1x6 board on the floor behind the stack, tilted to a 45 angle. Our approach was to build and operate a small dehumidification dry kiln. /Name /ImagePart_0 Drying lumber too quickly can lead to deep end checking, warping and case hardening. The kiln climate is controlled by venting the hot air and replacing it with ambient air. Kiln drying normally involves temperatures in the range of 40-75 C (about 100-170 F). Rep. FPL-GTR-57. (116 C) temperature. Each layer adds approximately .81 R value. 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. 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 After two days operating only the fans and DH, I take note of the temperature. You won't ever have the fastest kiln in town, but it can still work. Difficult-to-dry species might not exceed 140 degrees F. Dehumidification kilns are very . Basically, you dont want all of the air rushing out under the stack, so find a way to redirect it. This can be done by heating above 133F for 4 hours (measured at the core of the wood), or at 120F for about 7 - 10 days. Although dehumidification kilns are slower than conventional kilns for drying, the lower drying temperature has the reported advantage of less degrade and less shrinkage. 0000002536 00000 n They are normally mounted in the gable of household attics, and they are designed to be used in high temperature environments. Each layer of lumber is separated from the next by a series of "stickers" or spacer sticks. 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. Any info or advice on using dehumidification equipment to dry out chainsaw milled lumber. For all kiln drying schedules, a heater should be used to sterilize the lumber and kill any insects that may be present. Initially, I set the DH to 40% RH, because I dont want to remove moisture too quickly. This fact sheet summarizes the basics of kiln drying wood, the most commonly used methods, drying schedules and some drying defects. %3.3 This Blue&White Ginger Jar is a stunning piece of porcelain and pottery, expertly handcrafted with natural variations in each piece. Then align each subsequent layer of stickers over the last. Dehumidification drying system. << Taking moisture away at the rate the board will "safely" part with it . 0 In vacuum kiln trials, logs were heated to 56C at 70 percent log radius depth and the temperature maintained for . By setting the relative humidity (RH) on the dehumidifier, you can control how often it runs. A household dehumidifier (DH) removes moisture from the kiln chamber. Custom Doors, Drawers & Glass Accessories, Using a Small Scale Dehumidification Kiln, Learn Woodworking Tips & Tricks with Rockler, High-quality brands and products you can trust, Expert advice and free post-purchase support, Exclusive, innovative products that help you Create with Confidence, Detailed instructions, technical specs and guides to make the most of your purchases. 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. Not bragging or anything! Our next kiln charge is scheduled to begin around February 6, 2023. To condition the lumber, I introduce steam into the kiln for about two hours. BE CAREFUL--The first temperature value must be repeated for every MC class (column #2) that is above 30% MC. The Bolivian wood products industry was surveyed to determine lumber drying capacity, technology and.
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