dehumidification kiln drying schedules

Also, you can't really control well by measuring the collected water because some of the water leaks out with vented or leaking air. 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. This can create internal stress in the lumber that is released when sawing. The last thing to do before starting the kiln is to close the gable vent with an insulated cover. -. My baffles hang from T-bar assemblies mounted to the ceiling. 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. 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 . Our next kiln charge is scheduled to begin around February 6, 2023. 6. Basically the idea seems to be to maintain a constant temperature, and . 6. Low temperatures can be used for an extra safety margin on greener lumber. Without baffles, the top layers of lumber experience "potato chipping" with cupping, twisting or warping. This lets the operator sort stacks by lumber species, so they will be easy to retrieve when the drying cycle is complete. A better choice might be a solar kiln, as you can dry wood from "wet" to 6-8 percent MC in 6-8 weeks. Although dehumidification kilns are slower than conventional kilns for drying, the lower drying temperature has the reported advantage of less degrade and less shrinkage. The membrane was taped and lapped to the weather so if the tape ever fails, any rain that gets behind the siding would still be shed down and away by the HomeWrap. This report contains suggested dry kiln schedules for over 500 commercial woods, both temperate and tropical. I then manually rotate the fan boxes halfway through the drying cycle. Dehumidification drying system. They are easy to use and give you precision control over your drying. This slows the end-grain drying and limits the severity of end checking. Appendix B . 282 0 obj <> endobj Although I can maintain the 90 degree temperature, I could not start at the recommended humidity level unless I added humidity. To hang the baffles, simply attach hooks to the plywood frame. Once the core readings are 6% to 8% on a fresh cut, the lumber is dry and ready for sterilization. A small electric heater supplies auxiliary heat to maintain adequate kiln temperature. 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. 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Schedules. %PDF-1.5 I made a simple frame from plywood strips and attached theinsulation sheets to them with screws and fender washers. Dehumidification Kiln. the Dry Kiln Operator's Manual (Simpson, 1991). With a 130 F kiln temperature, sterilization will take 10 to 12 hours ( Dry Kiln Operators Manual, 1991 ). Initially, I set the DH to 40% RH, because I dont want to remove moisture too quickly. The store will not work correctly in the case when cookies are disabled. 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 . Select a heater with an adjustable thermostat and a tip-over shutoff. This allows for a more gentle kiln schedule to fully dry the timber. If the temperature is below this range, I start the heater and adjust the thermostat accordingly. Job Opportunities and Woodworking Services, Dust Collection, Safety and Plant Operation, Air-Drying and Kiln-Drying Methods for Wide Plank Flooring, Drying lumber - selecting the best method. %3.3 Staggering the seams between the sheathing and siding layers helps avoid air infiltration. In a professional DH kiln, the final climate for oak is 120F and <40>t over-dry it at that rate. The DH is not needed at this time, as the lumber is already bone-dry. (A major source was Dry Kiln Schedules for Commercial Woods which is available from the Forest Products Society in Madison, WI.) Dehumidifier suggestion: http://amzn.to/2iYZqVZThis is the first in a series of videos showing how I built a kiln for drying lumber. >> Omitting the sterilization phase can lead to costly losses from insect damage, so don't skip it. There might be a problem with that if the chamber overheats and has to be vented because some water will leave that way. Attic fans are a perfect way to provide airflow over the stacks of lumber. When the operating conditions of this option are followed the material will meet the requirements of being kiln dried (KD) and heat treated . 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? Soon the DH wont show much water collected in the tray. . I dont think the same could be said for an old reefer truck converted into a kiln (no matter how well it dries lumber). Warp in dimension lumber is a significant cause for loss in grade and value. I then manually rotate the fan boxes halfway through the drying cycle. This will allow the DH to drain automatically without you needing to enter the kiln. A dehumidification kiln makes sense particularly when the lumber is air-dried first. Official websites use .gov A shed kiln is an attractive alternative for a couple of reasons. Size and placement of the access door are critical as well. . A.gov website belongs to an official government The last step requires a short period of high humidity to relieve the drying stresses in the boards. My baffles hang from T-bar assemblies mounted to the ceiling. 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. Kiln drying is almost always essential for wood intended for interior uses. Take the electronics out of the kiln, and continue operating the heater and fans during this phase. Then align each subsequent layer of stickers over the last. Commercial scale steam kilns consume large amounts of energy. The problems with solar kilns include limited control over temperature and limited solar exposure, depending on your region and site location. Take the electronics out of the kiln, and continue operating the heater and fans during this phase. Sears Canada 70 Pint Dehumidifier. Loading the kiln begins by rousing my sons and letting them know Ive planned a day of work. Question A higher humidity setting will run the unit sporadically to maintain that RH. Once the lumber is sterilized, it is ready for the conditioning phase. Case hardening is a defect caused by the outer portion of a board drying quickly, while the inner portion dries more slowly. I've been drying hardwood lumber in this Sauno dehumidification kiln for 4 years with excellent results. Table 1 shows a typical drying schedule for sugar maple. Vacuum Kiln Drying. Temps are in Celsius (20C = 70F, 40C = 105F). USDA, 1991) . This would allow a stack of lumber four feet wide and 10 feet long. Insulation for walls and ceilings should be a minimum of R13. Reply. Add up the amp draw on all the equipment you plan to use in the kiln, including a heater, dehumidifier, fans and steam generator. A bead of silicone caulking between the subfloor and sill plate will prevent air infiltration. Minus the drying equipment, a shed kiln is just an insulated storage space, with a host of possible uses. Electrical requirements for a DIY kiln are pretty straightforward, but hiring an electrician is still a good idea. A lazy Susan with 180 detents mounts the fan box to the ceiling. Culm parts with 2.0 and 2.2 m length after pressure treatment were dried in industrial kilns using three schedules with mild, severe and highly severe drying intensity. Kiln Structure . 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 . A dehumidification kiln continuously recycles the heat throughout the chamber, rather than . Installing a window in a kiln may seem counterintuitive at first, because windows lose more heat than an insulated wall. building the dehumidification dry kiln. 2. HT systems use 40-60% less energy than gas-fired or steam dry kilns. Any small building could work, as long as it has a minimum of 2 x 4 framing, and will seal out unwanted air. The conversion method described in the Dry Kiln Operator's Manual is not really accurate, but it is safe. Kiln drying is usually preceded by air drying to bring the moisture content of the wood down below 30%. Rocky Mountain . The velocity through the load is assumed to be between 275 and . In smaller kilns, the heat generated by the fans and DH motor is sufficient to maintain temperatures in excess of 100 degrees. This will allow the heater to cycle on and off automatically, according to the kiln operators setting. Secure .gov websites use HTTPS 8. They are easy to use and give you precision control over your drying. Abstract. 301 0 obj <>stream (I use the Mini-Ligno MD/C from Lignomat, www.lignomatusa.com.) The second most common type of drying is called dehumidification drying. Drying lumber too quickly can lead to deep end checking, warping and case hardening. Schedule for drying 4/4 and 5/4 upland red oak in a steam dry kiln. The common lumber name is used throughout. Ciencia y Tecnologia, Duygu Kocaefe, Ayhan Aytin, The Bolivian secondary forest products industry has experienced substantial growth during the last 10 years. Always avoid conditions that add moisture back to the lumber, especially during start-up. This helps keep the lumber straight during the drying cycle; in fact, improper placement of stickers can permanently deform lumber. I can show you the kiln schedules and data. By setting the relative humidity (RH) on the dehumidifier, you can control how often it runs. If the fans and dehumidifer generate enough heat to maintain a temperature of 100 to 120 F, then I wont use the auxiliary heater. Share. 0000001208 00000 n 0000004213 00000 n 0000002536 00000 n These well-known dehumidification kiln packages have been among our bestselling products for the past 30 years. Frequently, the lumber has already air-dried for several years in a barn or outbuilding. Chinese, Korean or Japanese kilns have an arch roof. 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. 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. There are two ways to remove water from the DH unit, and they both work well. Items shipped directly from the manufacturer cannot be returned in store. Taking moisture away at the rate the board will "safely" part with it . 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 . Sticker spacing can be increased to 24 apart for 5/4 or thicker hardwood. Additionally, a 12 air plenum is required between the walls and stacks of lumber. 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. Another great option is to convert an existing shed or outbuilding to a lumber kiln. Phytosanitary heat treatments of Ceratocystis lukuohia and Ceratocystis huliohia-colonized Metrosideros polymorpha wood were evaluated using kilns. /Filter /JBIG2Decode They are normally mounted in the gable of household attics, and they are designed to be used in high temperature environments. To accommodate the floor insulation, blocking between joists is oriented horizontally instead of the normal vertical position. Schedules Dry Kiln Schedules for Commercial Woods . /Name /ImagePart_0 If you use a lot of lumber, and youre a decent hand at carpentry, a shed kiln will quickly pay for itself. I have been reading & studying kiln schedules for years too. 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). Align the stickers over the starter blocks on the first course. I find that unplugging the DH is helpful during the sterilization phase so I can add a second heater, without overwhelming my electrical circuit. When that is the case, I know Ill have usable lumber in just a few weeks. A discussion of how to apply "safe drying rate" calibrations with a home-built dehumidifying kiln. ) or https:// means youve safely connected to the .gov website. Standard kiln drying temperatures are low - around 120 degrees Fahrenheit or so, and drying times vary by wood size and moisture level. Wood drying (also seasoning lumber or wood seasoning) reduces the moisture content of wood before its use. Total costs for the materials were $2,704 based on 2006 prices. I modified one of the Radio Shack combo units so it could measure the RH remotely as well as the temp. An official website of the United States government. The T-bars are made from 1/2 galvanized pipe and are attached to the rafters with threaded pipe flanges. hb```[@9p(T-3jO:g)@S 4Y]g7l\V!c!$Bf J B@&xcEz8PH@ZHs1/X$qOq,x'x$0.rWg*d XAT10 );9 %PDF-1.6 % In addition, weight on top of the stack can be helpful, but nothing replaces baffles for the best lumber yield. Difficult-to-dry species might not exceed 140 degrees F. Dehumidification kilns are very . 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. A kiln schedule is a set of temperatures and humidities that are used during kiln operation. I'm thinking I could vent it manually, but with the RH so high externally I am not sure if that is the right thing to do. Each layer adds approximately .81 R value. Y}-m+'@DQ4\h8GP]y@ yL. But kiln drying may also introduce internal stresses into the woodparticularly if an improper kiln schedule is used, . Place a sticker at each end, and every 16 along the stack for 4/4 stock. (Dry Kiln Operator's Manual. If you dry 9,500BF of slower drying Oak, youd use the 10MBF chamber with the HT8 Dehumidifier. Should I? Typical . Enter the email address you signed up with and we'll email you a reset link. For the sterilization phase, air temperature needs to be around 140 F, for three to five hours. This gives me a secondary method of tracking the drying process, using both water volume and moisture content (MC) readings. We proudly stand behind all of our products. Khmer Kiln: quite similar to the Anagama kiln however, traditional Khmer Kilns had a flat roof. The second temperature value is written for the 25 to 30% MC class; the third for the 20 to 25% MC class; and so on. The schedules are all moisture content based, using the moisture content of the wettest half of the kiln samples. Dehumidification Opportunities for Dehumidification Drying Of Hardwood Lumber Dimension Kiln Drying Hardwood Dimension Parts Discoloration Preventing Discolorations in Hardwood and Softwood Logs . A household dehumidifier (DH) removes moisture from the kiln chamber. Soon the DH won't show much water collected in the tray. Conventional kiln drying. For more capacity, consider a two stack kiln (12 x 12), or a three-stack kiln (12 x 16). For example, if you dry 7,500BF of fast drying Pine, youd select the 8MBF chamber with the HT18 Dehumidifier. With each load I did not have the initial relative humidity rate. A higher humidity setting will run the unit sporadically to maintain that RH. Corners where walls meet should be sealed with expanding foam sealant. This makes lightweight baffles that can be easily moved and repositioned. Particularly, important investment has taken place in lumber drying capacity. My shed kiln was stick-built from standard building material, and sized to take advantage of typical 4 x 8 sheet goods. Main thing is to not rush drying in first stages, as this will cause problems. I either use some cedar 3" x 5", or 4" x 4" stock. In smaller kilns, the heat generated by the fans and DH motor is sufficient to maintain temperatures in excess of 100 degrees. For all kiln drying schedules, a heater should be used to sterilize the lumber and kill any insects that may be present. Construction of a kiln chamber is very similar to building a small house. Only the fans need electricity. 4. Case hardening is a defect caused by the outer portion of a board drying quickly, while the inner portion dries more slowly. the hardwood kiln schedule is the equalization of the moisture content of all boards at 6-8%. Measure airflow over the stacks of lumber in various locations. For end baffles, I use 2"-thick rigid foam insulation screwed to the main baffles. 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 End baffles are also a good idea to prevent airflow from bypassing the stack entirely. For a kiln temperature of 140 F, sterilization takes three to five hours. . This is because it needs to be dried to a lower moisture content than wood will air dry to outdoors. Different species should not be loaded simultaneously into the kiln due to often differing kiln schedules. 44. This helps keep the lumber straight during the drying cycle; in fact, improper placement of stickers can permanently deform lumber. 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 locked padlock Measure airflow over the stacks of lumber in various locations. For single-stack kilns, stationary fans are adequate. I like these starter blocks to raise the lumber a few inches off the floor. Over 40 years experience building kilns. 5. Dehumidification kiln schedules 145 Sterilizing, equalizing, and conditioning treatments 145 Sterilizing treatments 145 Mold 145 Fungal stain and decay 146 . 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. A shed kiln has minimal venting (usually one or two gable vents) and sealed soffits. Drying small amounts of lumber using a dehumidification kiln is a suitable option for woodworkers even with limited knowledge of kilns.