(I use the Mini-Ligno MD/C from Lignomat, www.lignomatusa.com.) The store will not work correctly in the case when cookies are disabled. %PDF-1.6 % For the sterilization phase, air temperature needs to be around 140 F, for three to five hours. Low Temperature Kiln Drying Systems (120F), High Temperature Kiln Drying Systems (160F), Very High Temperature Kiln Drying Systems (220F), Website Content Copyright 2023 Nyle Systems |, Affordable and easy method to accomplish top quality lumber drying, Designed specifically for any sized operation, Modular based systems for unlimited capacity, No boiler or steam required with gas furnace, Can be installed along side existing kilns, Chambers are sized with our DH systems to meet your lumber drying requirements. By setting the relative humidity (RH) on the dehumidifier, you can control how often it runs. All of these products were purchased at a local home center, except the remote hygrometer/thermometer which was purchased at a local electronics store. This listing incorporates current market requirements for the various species, as well as the current quality of the lumber resource itself. They are easy to use and give you precision control over your drying. Know how to choose and apply the correct schedule for the lumber. building the dehumidification dry kiln. Most species of hardwood lumber can be safely dried this way, once the moisture content is 20% to 25% or less. Vote. Bring your moisture meter to confirm. >> The fact is, most of my stacks of lumber air dry to 15% moisture content before entering the kiln. In contrast, a dehumidification kiln uses a sealed chamber, with only enough energy input to maintain the desired temperature. My kiln schedule starts with running all fans and the dehumidifier for two days, measuring and removing water as it accumulates. This fact sheet summarizes the basics of kiln drying wood, the most commonly used methods, drying schedules and some drying defects. USDA, 1991) . Then align each subsequent layer of stickers over the last. November 1, 2020. I find that unplugging the DH is helpful during the sterilization phase so I can add a second heater, without overwhelming my electrical circuit. This shed will be essentially unheated for much of the year and very hot during the kiln-drying cycles. For a single-stack kiln I recommend a minimum shed size of 8 x 12. For end baffles, I use 2"-thick rigid foam insulation screwed to the main baffles. Choosing a Kiln Schedule . An outswing door can always be opened, regardless of shed contents. Ideally, a lumber kiln would be large enough to dry multiple stacks of lumber. 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. To hang the baffles, simply attach hooks to the plywood frame. H6`2}s=n:l)CR>/"\ This is because it needs to be dried to a lower moisture content than wood will air dry to outdoors. Then align each subsequent layer of stickers over the last. Initially, I set the DH to 40% RH, because I dont want to remove moisture too quickly. Excel Program for Modeling Lumber Dry Kiln Operations - a model for lumber dry kiln operation. I guess I am thinking that while I am seeing the wood's MC and the kiln's RH drop smoothly, the fact that the temperature jumps around a bit may mean that the drying rates are hard to control, hence my loss of horse chestnut. Staggering the seams between the sheathing and siding layers helps avoid air infiltration. After two days operating only the fans and DH, I take note of the temperature. WOODWEB is a registered trademark of Woodweb.com. The baffles do not need insulating properties, and plywood would work just as well. Our capacities are 4,000 board feet in a kiln . If the interior volume of a kiln becomes too large, basic heaters and home dehumidifiers may be inadequate to control the kiln environment. Lock Formulating a Kiln Schedule My four main baffles consist of sheets of 1" Styrofoam insulation. There are two ways to remove water from the DH unit, and they both work well. 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. Each layer of lumber is separated from the next by a series of stickers or spacer sticks. With a well-designed dehumidification kiln, hardwood lumber can be dried for mere pennies per board foot. Select 3/4" conduit brackets for hanging baffles on 1/2" galvanized pipe. Heat comes primarily from an integral dehumidification unit that also removes . Maderas. 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. My shed kiln was stick-built from standard building material, and sized to take advantage of typical 4 x 8 sheet goods. There might be a problem with that if the chamber overheats and has to be vented because some water will leave that way. BE CAREFUL--The first temperature value must be repeated for every MC class (column #2) that is above 30% MC. If you dry 9,500BF of slower drying Oak, youd use the 10MBF chamber with the HT8 Dehumidifier. Kiln Systems. For a kiln temperature of 140 F, sterilization takes three to five hours. On the last load of lumber I purchased, I saved $2.50 per board foot compared to retail prices for kiln-dried lumber. 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 1. a furnace or oven for burning, baking, or drying, especially one for calcining lime or firing pottery. I hope that the sawyer coated the ends of the lumber with Anchor-Seal or oil-based paint when it was green. noun: kiln; plural noun: kilns. A heavy-duty 1,500-watt space heater works fine. Dehumidification drying equipment is available, but an enclosure must be built to house the equipment and dry the lumber. This allows for a more gentle kiln schedule to fully dry the timber. In larger kilns, the heater may be needed in the latter part of the drying cycle. Both restrained and control boards were dried to approximately 9 percent moisture content, representative of final in-service condi- tions. Apply foil tape to the edges of the main baffles to help protect the Styrofoam. Drying small amounts of lumber using a dehumidification kiln is a suitable option for woodworkers even with limited knowledge of kilns. The T-bars are made from 1/2" galvanized pipe and are attached to the rafters with threaded pipe flanges. Case hardening is a defect caused by the outer portion of a board drying quickly, while the inner portion dries more slowly. hbbd``b` $ &UD\q@u 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. This serves a dual purpose of supporting the rigid foam insulation as well as stiffening the floor framing. Leave an air space between the rigid foam and subfloor for additional insulating properties. They are normally mounted in the gable of household attics, and they are designed to be used in high temperature environments. I then manually rotate the fan boxes halfway through the drying cycle. 44. High Temperature Kiln Drying Systems (160F) Loads up to 350,000 BF; Pull up to 20,000 pounds of water daily; Use standard drying schedule; Precision temperature and RH . My kiln schedule starts with running all fans and the dehumidifier for two days, measuring and removing water as it accumulates. I've been drying hardwood lumber in this Sauno dehumidification kiln for 4 years with excellent results. 301 0 obj <>stream 3. Whether to Wax Walnut Ends Before Steaming, Frequently Asked Questions about Widebelt Sanders. 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. A lower RH setting will call for the DH to run more often. I found that brackets for mounting rigid metal electrical conduit work best. 0000001186 00000 n Sign In Upload. The DH is not needed at this time, as the lumber is already bone-dry. Dehumidification kiln schedules 145 Sterilizing, equalizing, and conditioning treatments 145 Sterilizing treatments 145 Mold 145 Fungal stain and decay 146 . This helps keep the lumber straight during the drying cycle; in fact, improper placement of stickers can permanently deform lumber. The four charges of lumber ranged from 600 to 700 board feet (bf), and a woodworker with no dry-kiln experience operated the kiln. 0000001208 00000 n Thus, a drying program can be adapted according to the characteristics of the kiln load, e.g., species, dimensions, and moisture content. Wood Drying/ Seasoning. 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. Another reason I like the idea of a shed kiln is the flexibility of future use. Check your local building codes for regionally specific requirements and electrical permits. Looking at the cost-benefit analysis of a shed kiln can be enlightening. Conventional kiln drying. Adjust the baffles or fan direction to achieve good airflow. My baffles hang from T-bar assemblies mounted to the ceiling. Built properly, a shed kiln may even increase the value of a property. Khmer Kiln: quite similar to the Anagama kiln however, traditional Khmer Kilns had a flat roof. 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 sheetrock also helps to protect the fiberglass insulation. Reweigh and obtain the oven dry weight. I am removing water about 50% below the SDR. Should a Moulding Mill Bring Sawmill Operations In-House? Table 1 shows a typical drying schedule for sugar maple. Select a heater with an adjustable thermostat and a tip-over shutoff. 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. . /Filter /JBIG2Decode Kiln drying normally involves temperatures in the range of 40-75 C (about 100-170 F). To accommodate the floor insulation, blocking between joists is oriented horizontally instead of the normal vertical position. Wood Shrink/Swell estimator - A web-based program to estimate shrink/ swell in wood. I cannot stress the importance of baffles enough. A dehumidification kiln makes sense particularly when the lumber is air-dried first. Dont even think of powering your kiln with an extension cord. Operates at a temperature range from 80F - 160F (26 - 71C). There are many types of kilns, but the most common are dehumidification kilns and conventional kilns. Extruded polystyrene foam (blue or pink rigid foam) in this thickness has an R value of 10. Main thing is to not rush drying in first stages, as this will cause problems. noun. Adjust the baffles or fan direction to achieve good airflow. (A major source was Dry Kiln Schedules for Commercial Woods which is available from the Forest Products Society in Madison, WI.) 9. Difficult-to-dry species might not exceed 140 degrees F. Dehumidification kilns are very . You can download the paper by clicking the button above. 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 Additionally, I have been underwhelmed by the performance of solar-operated fans. 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. In-service replacement of warped 2 by 4's as wall studs or truss members is costly. 0000006274 00000 n The last step requires a short period of high humidity to relieve the drying stresses in the boards. However, if you kiln dry hardwood lumber that has already been air dried, the process is much more forgiving. My four main baffles consist of sheets of 1 Styrofoam insulation. (See the following sections for a discussion of how to develop a schedule from these designations.) Exterior sheathing and siding type also factors into the heat-holding ability of the structure. In addition, weight on top of the stack can be helpful, but nothing replaces baffles for the best lumber yield. If you cannot find exact match, look at SG of same family species. 7. I usually see a large volume of water in the DH each night when I check the kiln. A heavy-duty 1,500-watt space heater works fine. Unfortunately, little information is available regarding lumber drying technology and practices used, which is essential for the formulation of improvement strategies. Remove samples from the stack, and cut an inch or two off one end. Created and Presented by: Henco Viljoen and Elijah McCarty with Nyle Dry Kilns. 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. A household dehumidifier (DH) removes moisture from the kiln chamber. Typical . The moisture loss, drying time and drying defects were determined. After a short period of grumbling, they join me to lay down wood blocks for the first layer of lumber. The air flow rate through your stacks should be about 350FPM. Once the lumber is sterilized, it is ready for the conditioning phase. Instead of using expensive electrically reversible fans designed for commercial kilns, I came up with a simple hardware solution. The schedule designations use the popular U.S. Forest Products Laboratory designations. 0000000710 00000 n With a 130 F kiln temperature, sterilization will take 10 to 12 hours (Dry Kiln Operators Manual, 1991). They are easy to use and give you precision control over your drying. Air speed of 350 feet per minute is appropriate for common hardwoods such as oak and maple. Once the core readings are 6% to 8% on a fresh cut, the lumber is dry and ready for sterilization. 3.) For end baffles, I use 2-thick rigid foam insulation screwed to the main baffles. 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. 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. Website Content Copyright 2023 Nyle Systems |. Share sensitive information only on official, secure websites. Sticker spacing can be increased to 24 apart for 5/4 or thicker hardwood. If MC readings still arent at the desired range, the heat may need to be increased for the remainder of the drying cycle. We proudly stand behind all of our products. Drying lumber too quickly can lead to deep end checking, warping and case hardening. In addition, wood can be dried by special methods that include solar drying (use of greenhouse-type dryers or those equipped with solar collectors . This lets the operator sort stacks by lumber species, so they will be easy to retrieve when the drying cycle is complete. (In the original Dry Kiln Operators Manual written in the early 1950s, some species were not used in high quality products. For all kiln drying schedules, a heater should be used to sterilize the lumber and kill any insects that may be present. 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. End baffles are also a good idea to prevent airflow from bypassing the stack entirely. Place a sticker at each end, and every 16" along the stack for 4/4 stock. Dehumidification Opportunities for Dehumidification Drying Of Hardwood Lumber Dimension Kiln Drying Hardwood Dimension Parts Discoloration Preventing Discolorations in Hardwood and Softwood Logs . The KD150 Dehumidification Kiln Kit is a compact, entry-level dehumidification kiln for drying lumber between 300 and 1000 board feet. I use a Rockler steam generator, item #42826 (www.rockler.com). I cannot stress the importance of baffles enough. Select a heater with an adjustable thermostat and a tip-over shutoff. This problem is magnified if the lumber is thin or flatsawn. 2. (Note: This letter designation is related to the green MC of the species. 10. Gen. Tech. 4. For the best experience on our site, be sure to turn on Javascript in your browser. Add up the amp draw on all the equipment you plan to use in the kiln, including a heater, dehumidifier, fans and steam generator. Place some sample boards in the stack that will be easy to pull out for moisture testing later. 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. stream An official website of the United States government. 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. The order was 540 board feet (BF) of 5/4 white oak. 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. By. The cost associated with shed construction was similar to buying a prefabricated kit. Take a moisture reading in the end grain with a pin-type moisture meter or remote probe.) After four days, I decrease the RH setting on the DH to 30% and continue to run the fans. With two-stack and three stack kilns, it is better to have reversible fans to alter the direction of airflow mid-cycle. An Overview. Temps are in Celsius (20C = 70F, 40C = 105F). This gives me a secondary method of tracking the drying process, using both water volume and moisture content (MC) readings. I recently picked up a back issue of American Woodworker, #94 June 2002, that has a good article on constructing a simple DH kiln. Wood drying (also seasoning lumber or wood seasoning) reduces the moisture content of wood before its use. 0000002827 00000 n If severe enough, the lumber can develop honeycomb cracks throughout. When the operating conditions of this option are followed the material will meet the requirements of being kiln dried (KD) and heat treated . End baffles are also a good idea to prevent airflow from bypassing the stack entirely. This procedure is discussed in a following section. The stickers are uniform in size and usually 3/4" or 1" square. Download Table of Contents. 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. If the fans and dehumidifer generate enough heat to maintain a temperature of 100 to 120 F, then I wont use the auxiliary heater. The last thing to do before starting the kiln is to close the gable vent with an insulated cover. %%EOF Secure .gov websites use HTTPS 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.). You can achieve top-quality results with incredible efficiency. Loading the kiln begins by rousing my sons and letting them know Ive planned a day of work. /ColorSpace /DeviceGray A pre-hung steel exterior door is ideal in this situation, because it offers weatherstripping and is fully insulated. Kiln drying is usually preceded by air drying to bring the moisture content of the wood down below 30%. Among the various sizes of southern yellow pine (SYP) dimension lumber, 2 by 4 is produced in the greatest volume. Just walk out to the shed kiln and grab what you need from your custom-dried supply. Minus the drying equipment, a shed kiln is just an insulated storage space, with a host of possible uses. Installing sheetrock and fire taping is a good idea for a heated room. The lumber was then measured for crook, bow, and twist. For example, if you dry 7,500BF of fast drying Pine, youd select the 8MBF chamber with the HT18 Dehumidifier.
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