dehumidification kiln drying schedules dehumidification kiln drying schedules

Also, since heat rises, ceiling-mounted fans have the added benefit of circulating the warmest air over the lumber. Air speed of 350 feet per minute is appropriate for common hardwoods such as oak and maple. In Fig. In larger kilns, the heater may be needed in the latter part of the drying cycle. For international returns, please click here. 0000006297 00000 n Installing sheetrock and fire taping is a good idea for a heated room. With a well-designed dehumidification kiln, hardwood lumber can be dried for mere pennies per board foot. Also, you can't really control well by measuring the collected water because some of the water leaks out with vented or leaking air. A maximum 45 F depression often produces better lumber. HWn8gXA N,[mKJr2"Ec9,t After two days operating only the fans and DH, I take note of the temperature. This shed will be essentially unheated for much of the year and very hot during the kiln-drying cycles. This listing incorporates current market requirements for the various species, as well as the current quality of the lumber resource itself. There might be a problem with that if the chamber overheats and has to be vented because some water will leave that way. I dont think the same could be said for an old reefer truck converted into a kiln (no matter how well it dries lumber). 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. I chose double wall construction with 1/2 sheathing, and 1/2 T1-11 siding. 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. The T-bars are made from 1/2" galvanized pipe and are attached to the rafters with threaded pipe flanges. Many available kiln designs require a large, heavy door. In this research, a drying restraint system was evaluated as a means of warp reduction in 8- and 16-foot-long SYP lumber. The kiln humidity can be expressed as an EMC, relative humidity, or wet-bulb temperature. It is a good idea to sterilize the lumber at the end of the kiln run. The kiln humidity can be expressed as an EMC, relative humidity, or wet-bulb temperature. 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. the hardwood kiln schedule is the equalization of the moisture content of all boards at 6-8%. Loading the kiln begins by rousing my sons and letting them know Ive planned a day of work. /Height 2587 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 . Operates at a temperature range from 80F - 160F (26 - 71C). Hardwood lumber kiln drying schedules typically keep the dry bulb temperature below 180 F (82 C). The schedules can also be formulated manually as follows. Extruded polystyrene foam (blue or pink rigid foam) in this thickness has an R value of 10. This, of course, is gross savings; we must calculate electrical costs to determine the net savings: in this case, about $62. Initially, I set the DH to 40% RH, because I dont want to remove moisture too quickly. A shed kiln is an attractive alternative for a couple of reasons. Dr. Gene Wengert provides schedules for kiln drying hardwood lumber. For single-stack kilns, stationary fans are adequate. (A major source was Dry Kiln Schedules for Commercial Woods which is available from the Forest Products Society in Madison, WI.) In addition, weight on top of the stack can be helpful, but nothing replaces baffles for the best lumber yield. An anemometer confirms that your effort constructing baffles was worthwhile. Appendix B . For these items, please call the store where you purchased them or our customer service department at 1-800-376-7856 so we can assist you. If the temperature is below this range, I start the heater and adjust the thermostat accordingly. hbbd``b` $ &UD\q@u After four days, I decrease the RH setting on the DH to 30% and continue to run the fans. Commercial scale steam kilns consume large amounts of energy. 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. Basically, you dont want all of the air rushing out under the stack, so find a way to redirect it. Table 1 shows a typical drying schedule for sugar maple. If MC readings still arent at the desired range, the heat may need to be increased for the remainder of the drying cycle. Take the electronics out of the kiln, and continue operating the heater and fans during this phase. Kiln drying is usually preceded by air drying to bring the moisture content of the wood down below 30%. Different species should not be loaded simultaneously into the kiln due to often differing kiln schedules. You may also return purchases to a Rockler store near you for store credit. Nyle Systems dehumidification kiln packages are our best known product with nearly unlimited drying capabilities. Among dimension lumber, the 2- by 4-inch size is typically the most susceptible to warp for a variety of reasons. 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. End baffles are also a good idea to prevent airflow from bypassing the stack entirely. As you can recycle . , , o* j=d For a single-stack kiln I recommend a minimum shed size of 8 x 12. 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. A small electric heater supplies auxiliary heat to maintain adequate kiln temperature. The starter blocks should be as long as the stack is wide. I'm trying to find a timetable or drying schedule for the basic dehumidification kilns you see on youtube. Leave an air space between the rigid foam and subfloor for additional insulating properties. in the kiln to dry specific wood products at a satisfactory rate without causing objectionable drying defects. Question The lumber was then measured for crook, bow, and twist. I was hoping someone could point me in the right direction or share experience. The stickers are uniform in size and usually 3/4" or 1" square. However, if you kiln dry hardwood lumber that has already been air dried, the process is much more forgiving. Instead of using expensive electrically reversible fans designed for commercial kilns, I came up with a simple hardware solution. Featuring lower cost drying at speeds equal to gas & steam, these kilns are continuously exceeding industry standards and changing the game. 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. 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 like these "starter blocks" to raise the lumber a few inches off the floor. the Dry Kiln Operator's Manual (Simpson, 1991). You can download the paper by clicking the button above. 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. Kiln drying is almost always essential for wood intended for interior uses. Rep. FPL-GTR-57. Should a Moulding Mill Bring Sawmill Operations In-House? (Note: This letter designation is related to the green MC of the species. A free BASIC program to convert the designations into actual temperatures and humidities is available from the author. They are based on different air flow rates, etc. 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 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). The sheetrock also helps to protect the fiberglass insulation. Adjust the baffles or fan direction to achieve good airflow. For end baffles, I use 2-thick rigid foam insulation screwed to the main baffles. Such temperatures are high enough to kill insectsanother advantage of kiln drying over air drying. This will allow the DH to drain automatically without you needing to enter the kiln. Bring your moisture meter to confirm. Our capacities are 4,000 board feet in a kiln . Delete from my manuals. I usually see a large volume of water in the DH each night when I check the kiln. . Dehumidification dry kilns operate at lower drying temperatures (typically below 150F) than do conventional kilns, which results in longer drying schedules. Our approach was to build and operate a small dehumidification dry kiln. Any small building could work, as long as it has a minimum of 2 x 4 framing, and will seal out unwanted air. Madison, WI: U.S. Department of Agriculture, Forest Service, Forest Products Laboratory. 0000001417 00000 n Remote operation and networking is optional. A small electric heater supplies auxiliary heat to maintain adequate kiln temperature. I hope that the sawyer coated the ends of the lumber with Anchor-Seal or oil-based paint when it was green. My question focuses on the initial relative humidity featured in the Safe Drying Rate table. 0 \ Total costs for the materials were $2,704 based on 2006 prices. This kicker board will help distribute the airflow more evenly through all layers of lumber. I had these custom cut and I air dried them outside under a tarp for 6 to 18 months (depending on which load they came in on) and then I kiln dried them in a Nyle dehumidification kiln for 3 months. 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 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. For all kiln drying schedules, a heater should be used to sterilize the lumber and kill any insects that may be present. . Download Table of Contents. The company's small kilns can be configured for drying lumber, firewood, or heat-treating lumber or wood packaging. 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? Determine the equalization settings and conditioning settings, as required. In smaller kilns, the heat generated by the fans and DH motor is sufficient to maintain temperatures in excess of 100 degrees. . Difficult-to-dry species might not exceed 60 C (140 F). These figures hold true for lumber up to 2" thick. (See the following sections for a discussion of how to develop a schedule from these designations.) 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. The kiln configuration and a drying schedule can be input and the code in the Excel file will simulate . The air flow rate through your stacks should be about 350FPM. There are two ways to remove water from the DH unit, and they both work well. January 27, 2007. This is because it needs to be dried to a lower moisture content than wood will air dry to outdoors. /Name /ImagePart_0 Measure airflow over the stacks of lumber in various locations. When that is the case, I know Ill have usable lumber in just a few weeks. 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. John Baines Reply to Dann Barry 1 year ago 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 The DH is not needed at this time, as the lumber is already bone-dry. If you dry 9,500BF of slower drying Oak, youd use the 10MBF chamber with the HT8 Dehumidifier. Always use adequate samples representing both the wettest and driest lumber in the dryer. Kiln Systems. An anemometer confirms that your effort constructing baffles was worthwhile. For sterilizing thicker lumber, additional time is required. Also, for that approach to work, the chamber needs to be air tight. Also, since heat rises, ceiling-mounted fans have the added benefit of circulating the warmest air over the lumber. Any info or advice on using dehumidification equipment to dry out chainsaw milled lumber. This slows the end-grain drying and limits the severity of end checking. Case hardening is a defect caused by the outer portion of a board drying quickly, while the inner portion dries more slowly. Page 30 Wood-Mizer Figure 3-4 Drying Schedules Normal Schedule Alternate Schedule Moisture Content Dry Bulb Wet Bulb Dry Bulb Wet Bulb Group 2 Above 45% 90F 85F 100F 97F . Determine the correct designation, such as T3-D2 for 4/4 red oak. Go to the first number designation (the temperature designation) and find the corresponding temperatures in the table below. With advances in spray foam insulation, it may be possible to seal older, drafty structures as well. Kiln Structure . Q,kjifT33P[! Dehumidification drying equipment is available, but an enclosure must be built to house the equipment and dry the lumber. A lazy Susan with 180 detents mounts the fan box to the ceiling. 5. 0000002536 00000 n Schedules Dry Kiln Schedules for Commercial Woods 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. /Filter /JBIG2Decode In addition, wood can be dried by special methods that include solar drying (use of greenhouse-type dryers or those equipped with solar collectors . Projects included design, construction, installation and commissioning of heat-pump based dehumidification equipment for seafood and fish gelatin products, hardwood lumber kilns and laboratory testing. Electrical requirements for a DIY kiln are pretty straightforward, but hiring an electrician is still a good idea. If your lumber stack is built on starter blocks, you will need to limit airflow there as well. Although I can maintain the 90 degree temperature, I could not start at the recommended humidity level unless I added humidity. The KD150 Dehumidification Kiln Kit is a compact, entry-level dehumidification kiln for drying lumber between 300 and 1000 board feet. I know your kiln is absolutely tight and perfectly sealed, but it has to vent some or it would overheat. The fact is, most of my stacks of lumber air dry to 15% moisture content before entering the kiln. Difficult-to-dry species might not exceed 140 degrees F. Dehumidification kilns are very . My kiln uses four ceiling-mounted fans, each rated for 1,600 CFM. This gives me a secondary method of tracking the drying process, using both water volume and moisture content (MC) readings. 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). For single-stack kilns, stationary fans are adequate. The moisture loss, drying time and drying defects were determined. Schedules. Changing the position of the doorway in various kiln setups helps provide the best access to the stacks of lumber. A kiln schedule is a set of temperatures and humidities that are used during kiln operation. Place a sticker at each end, and every 16 along the stack for 4/4 stock. With each load I did not have the initial relative humidity rate. This will allow the heater to cycle on and off automatically, according to the kiln operators setting. Share. For end baffles, I use 2"-thick rigid foam insulation screwed to the main baffles. Dehumidification: This kiln-drying process requires the use of a heat pump system to remove water from the wood. Looking at the cost-benefit analysis of a shed kiln can be enlightening. A variety of wood drying kiln technologies exist today: conventional, dehumidification, solar, vacuum and radio frequency. If you use a lot of lumber, and youre a decent hand at carpentry, a shed kiln will quickly pay for itself. 9. The stickers are uniform in size and usually 3/4 or 1 square. Drying lumber too quickly can lead to deep end checking, warping and case hardening. Select 3/4 conduit brackets for hanging baffles on 1/2 galvanized pipe. I've been drying hardwood lumber in this Sauno dehumidification kiln for 4 years with excellent results. 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. 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. From contributor D: Without baffles, the top layers of lumber experience potato chipping with cupping, twisting or warping. When properly loaded, this kiln can dry approximately 600 board feet of 4/4" lumber. _0e`bd\ p@ Dr. Gene Wengert provides schedules for kiln drying hardwood lumber. You won't ever have the fastest kiln in town, but it can still work. Academia.edu no longer supports Internet Explorer. End baffles are also a good idea to prevent airflow from bypassing the stack entirely. In time schedules, dry- and wet . This can create internal stress in the lumber that is released when sawing. The approach described in the article where you try to keep the water leaving at a steady rate is fine. A dehumidification kiln continuously recycles the heat throughout the chamber, rather than . 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. - Model L300, L500, L1200-S Series - Medium Dehumidification Dry. 3.) 10. I found that brackets for mounting rigid metal electrical conduit work best. Drying lumber too quickly can lead to deep end checking, warping and case hardening. The conversion method described in the Dry Kiln Operator's Manual is not really accurate, but it is safe. We are proud of the quality of our products, and we stand behind them 100%. Not bragging or anything! This limits the amount of energy needed to bring lumber to the desired 6% to 8% moisture content. As a result, the kiln schedules were too severe. After seven to 10 days, I reverse the fan direction to make sure all stacks of lumber dry evenly. Wood Shrink/Swell estimator - A web-based program to estimate shrink/ swell in wood. 293 0 obj <>/Filter/FlateDecode/ID[<87A322ACC143C740A97F712BC6C2FBCD>]/Index[282 20]/Info 281 0 R/Length 68/Prev 378162/Root 283 0 R/Size 302/Type/XRef/W[1 2 1]>>stream Lay down the bead of caulking before raising the walls. For a small scale shed kiln, I recommend a maximum footprint of 200 square feet. 0000000591 00000 n Consider not only the space for the lumber stacks, but extra floor space to easily load and monitor the charge of lumber. Place a 16 board on the floor behind the stack, tilted to a 45 angle. Main thing is to not rush drying in first stages, as this will cause problems. Omitting the sterilization phase can lead to costly losses from insect damage, so don't skip it. Dehumidifier suggestion: http://amzn.to/2iYZqVZThis is the first in a series of videos showing how I built a kiln for drying lumber. Basically, you don't want all of the air rushing out under the stack, so find a way to redirect it. I use a Rockler steam generator, item #42826 (www.rockler.com). 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. 2. Phytosanitary heat treatments of Ceratocystis lukuohia and Ceratocystis huliohia-colonized Metrosideros polymorpha wood were evaluated using kilns. . Hardwood kiln drying schedules typically keep the dry bulb temperature below 80 C (176 F). For sterilizing thicker lumber, additional time is required. Once all the lumber is stacked and stickered, place baffles over the lumber. A lazy Susan with 180 detents mounts the fan box to the ceiling.