Gen. Tech. This helps keep the lumber straight during the drying cycle; in fact, improper placement of stickers can permanently deform lumber. Each layer of lumber is separated from the next by a series of "stickers" or spacer sticks. Staff. 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. I prefer to empty the water tray manually and record the volume of water collected. In a professional DH kiln, the final climate for oak is 120F and <40>t over-dry it at that rate. Also, for that approach to work, the chamber needs to be air tight. The first load was started with 60% and this load was started with 78%. However, the natural light and ventilation offered by a small window outweighs any disadvantages. Drying lumber too quickly can lead to deep end checking, warping and case hardening. This kicker board will help distribute the airflow more evenly through all layers of lumber. 10. Y}-m+'@DQ4\h8GP]y@ yL. Basically the idea seems to be to maintain a constant temperature, and . Anyway, I included my log of a load I did in Nov '06 for everyone's amusement. You can download the paper by clicking the button above. Main thing is to not rush drying in first stages, as this will cause problems. This allows for a more gentle kiln schedule to fully dry the timber. Nyle. 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. After two days operating only the fans and DH, I take note of the temperature. This Blue&White Ginger Jar is a stunning piece of porcelain and pottery, expertly handcrafted with natural variations in each piece. A heavy-duty 1,500-watt space heater works fine. For sterilizing thicker lumber, additional time is required. For end baffles, I use 2-thick rigid foam insulation screwed to the main baffles. 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. . An official website of the United States government. There are two ways to remove water from the DH unit, and they both work well. hTn8>_l7h.&E:Bem=C9n\8]lMPc. Low Temperature Kiln Drying Systems (120F) 300BF - 4000BF Capacity . The column on the right I added part way through is the kiln's internal RH. The remaining width allows for a 36-wide door and space for your drying equipment. Loading the kiln begins by rousing my sons and letting them know Ive planned a day of work. Regardless of size, allow for a 36 door that opens to a hallway of open space. noun. 1998. In smaller kilns, the heat generated by the fans and DH motor is sufficient to maintain temperatures in excess of 100 degrees. The DH is not needed at this time, as the lumber is already bone-dry. Dehumidification Kilns 8. Should I? ) or https:// means youve safely connected to the .gov website. Commercial scale steam kilns consume large amounts of energy. Dehumidification Kiln Drying. This procedure is discussed in a following section. Then align each subsequent layer of stickers over the last. I dont think the same could be said for an old reefer truck converted into a kiln (no matter how well it dries lumber). 0 During the conditioning process, the only equipment operating are the fans, heater and the steam generator no dehumidifier. In this paper, the effective schedules were further investigated for longer culm parts treated with boron. Air speed of 350 feet per minute is appropriate for common hardwoods such as oak and maple. The thinner the stock, the more critical sticker placement becomes. This would allow a stack of lumber four feet wide and 10 feet long. The problems with solar kilns include limited control over temperature and limited solar exposure, depending on your region and site location. There may be more depression values than required; ignore the extra depression values in this table. However, you may need more cycles depending on the species, moisture content, and size of the timber. I have sensors in the kiln for moisture levels & probes in the center of the wood attached to a lignomat moisture meter. 9. Dr. Gene Wengert provides schedules for kiln drying hardwood lumber. Any small building could work, as long as it has a minimum of 2 x 4 framing, and will seal out unwanted air. Unlike general shop space, bigger is not always better for kiln design. Once all the lumber is stacked and stickered, place baffles over the lumber. 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. Perhaps the best part: you wont need to calculate your lumber needs down to the board foot. Most species of hardwood lumber can be safely dried this way, once the moisture content is 20% to 25% or less. My kiln schedule starts with running all fans and the dehumidifier for two days, measuring and removing water as it accumulates. With a 130 F kiln temperature, sterilization will take 10 to 12 hours ( Dry Kiln Operators Manual, 1991 ). For more capacity, consider a two stack kiln (12 x 12), or a three-stack kiln (12 x 16). Check out More On the Web for my complete calculations to figure savings. November 1, 2020. 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. This problem is magnified if the lumber is thin or flatsawn. Then, write down the appropriate MC ranges (determined in #2 above) in the second column. Schedules. Case hardening is a defect caused by the outer portion of a board drying quickly, while the inner portion dries more slowly. Sticker spacing can be increased to 24" apart for 5/4 or thicker hardwood. Insulation for walls and ceilings should be a minimum of R13. Featuring lower cost drying at speeds equal to gas & steam, these kilns are continuously exceeding industry standards and changing the game. The first thing to consider when designing a shed kiln is size. I find that unplugging the DH is helpful during the sterilization phase so I can add a second heater, without overwhelming my electrical circuit. Among dimension lumber, the 2- by 4-inch size is typically the most susceptible to warp for a variety of reasons. A kiln schedule is a set of temperatures and humidities that are used during kiln operation. Enter the email address you signed up with and we'll email you a reset link. Manufacturer guarantees/warranties for power tools, CNC and laser products will supersede the Rockler Guarantee if these items are damaged or defective. This shed will be essentially unheated for much of the year and very hot during the kiln-drying cycles. 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. I then manually rotate the fan boxes halfway through the drying cycle. You can achieve top-quality results with incredible efficiency. HT systems use 40-60% less energy than gas-fired or steam dry kilns. For single-stack kilns, stationary fans are adequate. (I use the Mini-Ligno MD/C from Lignomat, www.lignomatusa.com.) After two days operating only the fans and DH, I take note of the temperature. Air speed of 350 feet per minute is appropriate for common hardwoods such as oak and maple. Take a moisture reading in the end grain with a pin-type moisture meter or remote probe. Maderas. The KD150 Dehumidification Kiln Kit is a compact, entry-level dehumidification kiln for drying lumber between 300 and 1000 board feet. Website Content Copyright 2023 Nyle Systems |. Kiln dried wood typically sells for a third more than green lumber and eliminates the need for . hbbd``b` $ &UD\q@u I then manually rotate the fan boxes halfway through the drying cycle. hb```[@9p(T-3jO:g)@S 4Y]g7l\V!c!$Bf J B@&xcEz8PH@ZHs1/X$qOq,x'x$0.rWg*d XAT10 );9 Add up the amp draw on all the equipment you plan to use in the kiln, including a heater, dehumidifier, fans and steam generator. The cost associated with shed construction was similar to buying a prefabricated kit. Would adding humidity at the start, bringing the initial relative humidity rate to 87% as suggested in the table, result in better product or faster drying? There might be a problem with that if the chamber overheats and has to be vented because some water will leave that way. The baffles direct airflow over and through the stack and prevent the top layers from drying too quickly. The second most common type of drying is called dehumidification drying. Dehumidification dry kilns operate at lower drying temperatures (typically below 150F) than do conventional kilns, which results in longer drying schedules. The velocity through the load is assumed to be between 275 and . 0000006297 00000 n Abstract. Operates at a temperature range from 80F - 160F (26 - 71C). Instead of using expensive electrically reversible fans designed for commercial kilns, I came up with a simple hardware solution. Lay down the bead of caulking before raising the walls. (See the following sections for a discussion of how to develop a schedule from these designations.) 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 Minus the drying equipment, a shed kiln is just an insulated storage space, with a host of possible uses. Question The thinner the stock, the more critical sticker placement becomes. Q,kjifT33P[! A 1.5-kW dehumidifier was installed in the solar dryer to determine the performance of a combined solar-dehumidification dryer. Although dehumidification kilns are slower than conventional kilns for drying, the lower drying temperature has the reported advantage of less degrade and less shrinkage. I modified one of the Radio Shack combo units so it could measure the RH remotely as well as the temp. For end baffles, I use 2"-thick rigid foam insulation screwed to the main baffles. Basically, you dont want all of the air rushing out under the stack, so find a way to redirect it. If it isn't overheating, it is leaking. 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. Attic fans are a perfect way to provide airflow over the stacks of lumber. These figures hold true for lumber up to 2" thick. Leave an air space between the rigid foam and subfloor for additional insulating properties. /Name /ImagePart_0 Kiln Drying . A variety of wood drying kiln technologies exist today: conventional, dehumidification, solar, vacuum and radio frequency. To accommodate the floor insulation, blocking between joists is oriented horizontally instead of the normal vertical position. are generally kiln dried by time scheduleswhether the wood is intended for struc-tural lumber or for appearance uses, such as furniture or millwork. 6 0 obj I have been reading & studying kiln schedules for years too. noun: kiln; plural noun: kilns. /Length 7 0 R For a small scale shed kiln, I recommend a maximum footprint of 200 square feet. Different species should not be loaded simultaneously into the kiln due to often differing kiln schedules. 6. In addition, weight on top of the stack can be helpful, but nothing replaces baffles for the best lumber yield. Dehumidifier suggestion: http://amzn.to/2iYZqVZThis is the first in a series of videos showing how I built a kiln for drying lumber. Dehumidification kilns from Nyle Systems in Brewer, Maine. BE CAREFUL--The first temperature value must be repeated for every MC class (column #2) that is above 30% MC. In time schedules, dry- and wet . 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. This limits the amount of energy needed to bring lumber to the desired 6% to 8% moisture content. 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? 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 Dont even think of powering your kiln with an extension cord. Each layer adds approximately .81 R value. The sheetrock also helps to protect the fiberglass insulation. 301 0 obj <>stream 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 These are rough-saw red oak. I am removing water about 50% below the SDR. For these reasons, I feel it is best to let the shed breathe, and forgo a plastic vapor barrier. I know mixed loads are taboo, but this one worked well, other than the horse chestnut. The kiln climate is controlled by venting the hot air and replacing it with ambient air. 0000000591 00000 n This kicker board will help distribute the airflow more evenly through all layers of lumber. 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%. Should a Moulding Mill Bring Sawmill Operations In-House? Schedule for drying 4/4 and 5/4 upland red oak in a steam dry kiln. . If you use a lot of lumber, and youre a decent hand at carpentry, a shed kiln will quickly pay for itself. The lumber was then measured for crook, bow, and twist. I use a Rockler steam generator, item #42826 (www.rockler.com). Kiln drying lumber is a simple, cost effective method recommended for anyone who wants to increase profits by selling dried lumber. This plan allows . 158 p. Dry kiln schedules for commercial woods : temperate and tropical. << Go to the first number designation (the temperature designation) and find the corresponding temperatures in the table below. I also wrapped the shed with Tyvek HomeWrap. It is a meaningless exercise to try to convert those schedules for the kiln you built. If the temperature is below this range, I start the heater and adjust the thermostat accordingly. With a 130 F kiln temperature, sterilization will take 10 to 12 hours ( Dry Kiln Operators Manual, 1991 ). However, if you kiln dry hardwood lumber that has already been air dried, the process is much more forgiving. Consider the weight of the lumber that will be placed in the structure and fortify the building accordingly. An outswing door can always be opened, regardless of shed contents. In contrast, a dehumidification kiln uses a sealed chamber, with only enough energy input to maintain the desired temperature. In Fig. This fact sheet summarizes the basics of kiln drying wood, the most commonly used methods, drying schedules and some drying defects. 0000004213 00000 n 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.. The air flow rate through your stacks should be about 350FPM. I can show you the kiln schedules and data. Made in China, it exudes the classic style of Asian and Chinese cultures, featuring a unique shape that sets it apart from traditional jars. Remove samples from the stack, and cut an inch or two off one end. Additionally, a 12 air plenum is required between the walls and stacks of lumber. The baffles do not need insulating properties, and plywood would work just as well. This gives me a secondary method of tracking the drying process, using both water volume and moisture content (MC) readings. A dehumidification kiln makes sense particularly when the lumber is air-dried first. Madison, WI: U.S. Department of Agriculture, Forest Service, Forest Products Laboratory. The schedules are all moisture content based, using the moisture content of the wettest half of the kiln samples. The order was 540 board feet (BF) of 5/4 white oak. During the conditioning process, the only equipment operating are the fans, heater and the steam generator no dehumidifier. . Temps are in Celsius (20C = 70F, 40C = 105F). Excel Program for Modeling Lumber Dry Kiln Operations - a model for lumber dry kiln operation. Kiln drying is the process of drying wood in a controlled environment, where temperature, air circulation and humidity are monitored and stabilized. I cannot stress the importance of baffles enough. What can you do to speed up drying time? Once the flooring deck is constructed, think about sealing the shed framing at every opportunity. building the dehumidification dry kiln. The stickers are uniform in size and usually 3/4 or 1 square. I recommend a 2 x 3 sliding window with bug screen. January 27, 2007. Select a heater with an adjustable thermostat and a tip-over shutoff. Dehumidification drying system. The T-bars are made from 1/2" galvanized pipe and are attached to the rafters with threaded pipe flanges. By setting the relative humidity (RH) on the dehumidifier, you can control how often it runs. A free BASIC program to convert the designations into actual temperatures and humidities is available from the author. Equalizing and Conditioning (I have found that remotely monitoring the temperature and humidity with a WiFi sensor can be very helpful. This is because it needs to be dried to a lower moisture content than wood will air dry to outdoors. After four days, I decrease the RH setting on the DH to 30% and continue to run the fans. Temperatures inside the kiln range from 120 to 190 degrees F, depending on the stage of . To hang the baffles, simply attach hooks to the plywood frame. 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.) This prevents "dead spots" inside the chamber that experience limited airflow. stream 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. You won't ever have the fastest kiln in town, but it can still work. _0e`bd\ p@ WOODWEB is a registered trademark of Woodweb.com. 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 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. Rocky Mountain . Also, since heat rises, ceiling-mounted fans have the added benefit of circulating the warmest air over the lumber. The fact is, most of my stacks of lumber air dry to 15% moisture content before entering the kiln. In addition, wood can be dried by special methods that include solar drying (use of greenhouse-type dryers or those equipped with solar collectors . Items shipped directly from the manufacturer cannot be returned in store. 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. kiln/. Although I can maintain the 90 degree temperature, I could not start at the recommended humidity level unless I added humidity. 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. Be sure that all of the kiln equipment is working prop-erly before lumber is loaded into the kiln. In the fourth column, write down the wet-bulb depressions (determined in #4 above), one for each Schedule Step, starting at the top (Schedule Step 1). If your lumber stack is built on starter blocks, you will need to limit airflow there as well. Thicker lumber like 5/4 or quartersawn lumber is naturally more stable. /Width 1628 For the best experience on our site, be sure to turn on Javascript in your browser. The last thing to do before starting the kiln is to close the gable vent with an insulated cover. In addition, weight on top of the stack can be helpful, but nothing replaces baffles for the best lumber yield. Schedules for several thicknesses and specialty products (e.g. An anemometer confirms that your effort constructing baffles was worthwhile. This makes lightweight baffles that can be easily moved and repositioned. Once the lumber is sterilized, it is ready for the conditioning phase. Total costs for the materials were $2,704 based on 2006 prices. 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 a kiln temperature of 140 F, sterilization takes three to five hours. If you cannot find exact match, look at SG of same family species. Wood drying (also seasoning lumber or wood seasoning) reduces the moisture content of wood before its use. For example, if you dry 7,500BF of fast drying Pine, youd select the 8MBF chamber with the HT18 Dehumidifier. the Dry Kiln Operator's Manual (Simpson, 1991). Size and placement of the access door are critical as well.