dehumidification kiln drying schedules

Saving money by drying your lumber may not be the answer for every woodworker, but the basics shown here demonstrate that it is within the reach and skills of the average person. Always avoid conditions that add moisture back to the lumber, especially during start-up. 44. 8. I usually see a large volume of water in the DH each night when I check the kiln. I have sensors in the kiln for moisture levels & probes in the center of the wood attached to a lignomat moisture meter. 3.) 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 4. The order was 540 board feet (BF) of 5/4 white oak. JavaScript seems to be disabled in your browser. A dry kiln needs to be operated when it is filled with lumber and forces airflow through the tiers of lumber instead of around the ends or over the top of the stack(s). An official website of the United States government. Measure airflow over the stacks of lumber in various locations. Also check that air isnt escaping around the side baffles or under the stack of lumber. Adjust the baffles or fan direction to achieve good airflow. Manufacturer guarantees/warranties for power tools, CNC and laser products will supersede the Rockler Guarantee if these items are damaged or defective. For the best experience on our site, be sure to turn on Javascript in your browser. 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. Subtract the wet-bulb depression from the dry-bulb temperatures for each schedule step and enter the value in the fifth column. Electrical requirements for a DIY kiln are pretty straightforward, but hiring an electrician is still a good idea. -. Formulating a Kiln Schedule Can also be used on any mobile device! In this system, moist air is not vented out of the kiln but is dehumidified, then recirculated . I find that unplugging the DH is helpful during the sterilization phase so I can add a second heater, without overwhelming my electrical circuit. A lock ( Dehumidification drying system. (In the original Dry Kiln Operators Manual written in the early 1950s, some species were not used in high quality products. I dont think the same could be said for an old reefer truck converted into a kiln (no matter how well it dries lumber). I like these starter blocks to raise the lumber a few inches off the floor. The kiln schedule information in the tables below has been assembled from many different sources, including drying texts and industrial contacts. If the fans and dehumidifer generate enough heat to maintain a temperature of 100 to 120 F, then I wont use the auxiliary heater. 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. This procedure is discussed in a following section. Omitting the sterilization phase can lead to costly losses from insect damage, so dont skip it. The remaining width allows for a 36-wide door and space for your drying equipment. For all kiln drying schedules, a heater should be used to sterilize the lumber and kill any insects that may be present. For the sterilization phase, air temperature needs to be around 140 F, for three to five hours. Should I? (116 C) temperature. Select a heater with an adjustable thermostat and a tip-over shutoff. 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.). My four main baffles consist of sheets of 1 Styrofoam insulation. Then align each subsequent layer of stickers over the last. For example, if you dry 7,500BF of fast drying Pine, you'd select the 8MBF chamber with the HT18 . /Name /ImagePart_0 I also wrapped the shed with Tyvek HomeWrap. I modified one of the Radio Shack combo units so it could measure the RH remotely as well as the temp. The schedule designations use the popular U.S. Forest Products Laboratory designations. Heat comes primarily from an integral dehumidification unit that also removes . 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. It can be constructed in any style, with architectural features that match or complement an existing home. 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 The starter blocks should be as long as the stack is wide. Unlike general shop space, bigger is not always better for kiln design. This slows the end-grain drying and limits the severity of end checking. Consider not only the space for the lumber stacks, but extra floor space to easily load and monitor the charge of lumber. The starter blocks should be as long as the stack is wide. /Height 2587 The baffles direct airflow over and through the stack and prevent the top layers from drying too quickly. Changing the position of the doorway in various kiln setups helps provide the best access to the stacks of lumber. A.gov website belongs to an official government Place a sticker at each end, and every 16 along the stack for 4/4 stock. USDA, 1991) . 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. Operates at a temperature range from 80F - 160F (26 - 71C). I either use some cedar 3 x 5, or 4 x 4 stock. These well-known dehumidification kiln packages have been among our bestselling products for the past 30 years. Omitting the sterilization phase can lead to costly losses from insect damage, so don't skip it. 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. The thinner the stock, the more critical sticker placement becomes. I prefer to empty the water tray manually and record the volume of water collected. Air speed of 350 feet per minute is appropriate for common hardwoods such as oak and maple. For sterilizing thicker lumber, additional time is required. Typical dehumidification kiln (FPL 1999 p. 12-10). A pre-hung steel exterior door is ideal in this situation, because it offers weatherstripping and is fully insulated. HT systems use 40-60% less energy than gas-fired or steam dry kilns. I use a Rockler steam generator. Academia.edu no longer supports Internet Explorer. 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. When properly loaded, this kiln can dry approximately 600 board feet of 4/4" lumber. Sign In Upload. Willie Sandry is a furniture maker and a lumber kiln operator in Camas, Washington. Case hardening is a defect caused by the outer portion of a board drying quickly, while the inner portion dries more slowly. John Baines Reply to Dann Barry 1 year ago 73. 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. This prevents "dead spots" inside the chamber that experience limited airflow. /Type /XObject If you cannot find exact match, look at SG of same family species. The cost associated with shed construction was similar to buying a prefabricated kit. Small, complete dehumidification dry kilns under 5,000 board-foot capacity are not available for sale. This, of course, is gross savings; we must calculate electrical costs to determine the net savings: in this case, about $62. 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 Soon the DH won't show much water collected in the tray. By setting the relative humidity (RH) on the dehumidifier, you can control how often it runs. Should a Moulding Mill Bring Sawmill Operations In-House? Question Lay down the bead of caulking before raising the walls. With a well-designed dehumidification kiln, hardwood lumber can be dried for mere pennies per board foot. are generally kiln dried by time scheduleswhether the wood is intended for struc-tural lumber or for appearance uses, such as furniture or millwork. Dont even think of powering your kiln with an extension cord. . 0 in the kiln to dry specific wood products at a satisfactory rate without causing objectionable drying defects. Go to the first number designation (the temperature designation) and find the corresponding temperatures in the table below. Total costs for the materials were $2,704 based on 2006 prices. Delete from my manuals. 301 0 obj <>stream I hope that the sawyer coated the ends of the lumber with Anchor-Seal or oil-based paint when it was green. I recommend a 2 x 3 sliding window with bug screen. For all kiln drying schedules, a heater should be used to sterilize the lumber and kill any insects that may be present. To condition the lumber, I introduce steam into the kiln for about two hours. A small electric heater supplies auxiliary heat to maintain adequate kiln temperature. A lower RH setting will call for the DH to run more often. Temps are in Celsius (20C = 70F, 40C = 105F). 5. My kiln uses four ceiling-mounted fans, each rated for 1,600 CFM. In the majority of cases, the drying schedules are from the world literature, with emphasis on U.S., Canadian, and British publications. 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. Wood Drying/ Seasoning. In Fig. Add up the amp draw on all the equipment you plan to use in the kiln, including a heater, dehumidifier, fans and steam generator. Although I can maintain the 90 degree temperature, I could not start at the recommended humidity level unless I added humidity. With a 130 F kiln temperature, sterilization will take 10 to 12 hours ( Dry Kiln Operators Manual, 1991 ). A dehumidification kiln makes sense particularly when the lumber is air-dried first. /Length 7 0 R Only the fans need electricity. Dehumidification drying equipment is available, but an enclosure must be built to house the equipment and dry the lumber.