dehumidification kiln drying schedules dehumidification kiln drying schedules

There are two ways to remove water from the DH unit, and they both work well. Contractors work on a tight schedule, and that may not allow much time for curing and drying concrete. Should I? There may be more depression values than required; ignore the extra depression values in this table. My kiln schedule starts with running all fans and the dehumidifier for two days, measuring and removing water as it accumulates. 3, a simplified transverse section of a kiln chamber with an energy recovery and dehumidification system is shown. This report contains suggested dry kiln schedules for over 500 commercial woods, both temperate and tropical. This returns some moisture to the very dry exterior of the lumber, while not affecting the core moisture level. They are based on different air flow rates, etc. (I have found that remotely monitoring the temperature and humidity with a WiFi sensor can be very helpful. Place a sticker at each end, and every 16" along the stack for 4/4 stock. They are easy to use and give you precision control over your drying. Loading the kiln begins by rousing my sons and letting them know Ive planned a day of work. Select 3/4 conduit brackets for hanging baffles on 1/2 galvanized pipe. With a 130 F kiln temperature, sterilization will take 10 to 12 hours (Dry Kiln Operators Manual, 1991). Extruded polystyrene foam (blue or pink rigid foam) in this thickness has an R value of 10. Minus the drying equipment, a shed kiln is just an insulated storage space, with a host of possible uses. 0000002827 00000 n Determine the correct designation, such as T3-D2 for 4/4 red oak. Usually, you need anywhere between five to eight kiln schedules to complete the process. 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 . In addition, wood can be dried by special methods that include solar drying (use of greenhouse-type dryers or those equipped with solar collectors . 0000000710 00000 n endstream endobj startxref In time schedules, dry- and wet . It can be constructed in any style, with architectural features that match or complement an existing home. 6. This prevents dead spots inside the chamber that experience limited airflow. Always avoid conditions that add moisture back to the lumber, especially during start-up. 0000002536 00000 n After four days, I decrease the RH setting on the DH to 30% and continue to run the fans. . 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. For international returns, please click here. Job Opportunities and Woodworking Services, Dust Collection, Safety and Plant Operation. I am also curious why an initial temperature of 90F would have been selected. /Length 7 0 R Kiln dried wood typically sells for a third more than green lumber and eliminates the need for . Taking moisture away at the rate the board will "safely" part with it . Over 40 years experience building kilns. Leave an air space between the rigid foam and subfloor for additional insulating properties. Q,kjifT33P[! However, you may need more cycles depending on the species, moisture content, and size of the timber. Regardless of size, allow for a 36 door that opens to a hallway of open space. Changing the position of the doorway in various kiln setups helps provide the best access to the stacks of lumber. An Overview. Also, you can't really control well by measuring the collected water because some of the water leaks out with vented or leaking air. This listing incorporates current market requirements for the various species, as well as the current quality of the lumber resource itself. Kiln drying lumber is a simple, cost effective method recommended for anyone who wants to increase profits by selling dried lumber. The dry kiln operator is fully in control, with the ability to make changes as the dry kiln schedule is executing. A household dehumidifier (DH) removes moisture from the kiln chamber. I cannot stress the importance of baffles enough. My four main baffles consist of sheets of 1 Styrofoam insulation. Check your local building codes for regionally specific requirements and electrical permits. My baffles hang from T-bar assemblies mounted to the ceiling. 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 . To accommodate the floor insulation, blocking between joists is oriented horizontally instead of the normal vertical position. Hardwood lumber kiln drying schedules typically keep the dry bulb temperature below 180 F (82 C). My baffles hang from T-bar assemblies mounted to the ceiling. My kiln uses four ceiling-mounted fans, each rated for 1,600 CFM. Kiln drying lumber is a simple, cost effective method recommended for anyone who wants to increase profits by selling dried lumber. It is a meaningless exercise to try to convert those schedules for the kiln you built. I'd like to know for my own curiosity, as well as to be able to generate SDR schedules for other species not given in the American Woodworker article, like the 6 foot long 24" wide slabs of 8/4 madrone I got this summer. This gives me a secondary method of tracking the drying process, using both water volume and moisture content (MC) readings. For end baffles, I use 2-thick rigid foam insulation screwed to the main baffles. Adjust the baffles or fan direction to achieve good airflow. Willie Sandry is a furniture maker and a lumber kiln operator in Camas, Washington. The starter blocks should be as long as the stack is wide. 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 What can you do to speed up drying time? They are normally mounted in the gable of household attics, and they are designed to be used in high temperature environments. 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. Madison, WI: U.S. Department of Agriculture, Forest Service, Forest Products Laboratory. To condition the lumber, I introduce steam into the kiln for about two hours. If you dry 9,500BF of slower drying Oak, youd use the 10MBF chamber with the HT8 Dehumidifier. With two-stack and three stack kilns, it is better to have reversible fans to alter the direction of airflow mid-cycle. When the operating conditions of this option are followed the material will meet the requirements of being kiln dried (KD) and heat treated . Be sure that all of the kiln equipment is working prop-erly before lumber is loaded into the kiln. Wood poles subjected to a 22- to 34-day dehumidification kiln schedule with a heat treatment to 60C to the poles' core. 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. Kiln Systems. Excel Program for Modeling Lumber Dry Kiln Operations - a model for lumber dry kiln operation. Share. /Filter /JBIG2Decode Among dimension lumber, the 2- by 4-inch size is typically the most susceptible to warp for a variety of reasons. Evaluation of kiln-drying schedules for wild cherry wood (Cerasus avium), Model to assess energy consumption in industrial lumber kilns, Mathematical modelling and experimental investigation of dehumidifier drying of radiata pine timber, A survey of Bolivian lumber drying operations, Warp reduction of SYP lumber by restrained drying, Western Juniper Drying Project Summaries, 1993-96, Vacuum contact drying kinetics of Jack pine wood and its influence on mechanical properties: industrial applications, Kiln drying behavior of lumber from ten fast-growth plantation species in Costa Rica, Effect of fire-retardant treatment and redrying on the mechanical properties of Douglas-fir and aspen plywood, Properties of Douglas-Fir and Aspen Plywood, A numerical study on the influence of the bond-line diffusivity on moisture-related stresses and deformations of three-layered spruce cross-laminates, Error in Estimates of the Moisture Content of White Oak Kiln Sample Boards, Green Kerfing Treatment for Improving Softwood Lumber Drying: A Review, A comparison of kiln-drying schedules and quality outcomes for 4/4-thickness black cherry lumber sawn from small-diameter logs, A comparison of kiln-drying schedules and quality outcomes in 4/4-thickness black cherry lumber sawn from small-diameter logs, Data bank for short-length red oak lumber, Hardwood lumber widths and grades used by the furniture and cabinet industries: Results of a 14-mill survey, Lumber and veneer recovery from intensively managed young-growth Douglas-fir, WOOD-FRAME HOUSE CONSTRUCTION U.S. DEPARTMENT OF AGRICULTURE FOREST SERVICBAGRICULTURE HANDBOOK NO. %PDF-1.4 % Made in China, it exudes the classic style of Asian and Chinese cultures, featuring a unique shape that sets it apart from traditional jars. 1. a furnace or oven for burning, baking, or drying, especially one for calcining lime or firing pottery. November 1, 2020. You can download the paper by clicking the button above. All of these products were purchased at a local home center, except the remote hygrometer/thermometer which was purchased at a local electronics store. Use the gridded drawings provided on the PDF, Woodworking | Blog | Videos | Plans | How To. This shed will be essentially unheated for much of the year and very hot during the kiln-drying cycles. Dehumidification kilns are similar to other kilns in basic construction and drying times are usually comparable. Place some sample boards in the stack that will be easy to pull out for moisture testing later. These figures hold true for lumber up to 2" thick. Dehumidification Kiln. With two-stack and three stack kilns, it is better to have reversible fans to alter the direction of airflow mid-cycle. Sign In Upload. My number one priority was to build a kiln that was easy to load and easy to monitor. Consider not only the space for the lumber stacks, but extra floor space to easily load and monitor the charge of lumber. Once the core readings are 6% to 8% on a fresh cut, the lumber is dry and ready for sterilization. Insulation for walls and ceilings should be a minimum of R13. the Dry Kiln Operator's Manual (Simpson, 1991). The common lumber name is used throughout. 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. 282 0 obj <> endobj Choosing a Kiln Schedule Phytosanitary heat treatments of Ceratocystis lukuohia and Ceratocystis huliohia-colonized Metrosideros polymorpha wood were evaluated using kilns. I prefer to empty the water tray manually and record the volume of water collected. You could use the dehumidifier to dry wood but it would not be part of a "kiln." Just be a different process. I often buy from sawyers or homeowners at 40% to 50% of retail price. The baffles direct airflow over and through the stack and prevent the top layers from drying too quickly. 1998. by Dr. Eugene Wengert. 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. hb```[@9p(T-3jO:g)@S 4Y]g7l\V!c!$Bf J B@&xcEz8PH@ZHs1/X$qOq,x'x$0.rWg*d XAT10 );9 If MC readings still arent at the desired range, the heat may need to be increased for the remainder of the drying cycle. Schedule for drying 4/4 and 5/4 upland red oak in a steam dry kiln. A small electric heater supplies auxiliary heat to maintain adequate kiln temperature. Measure airflow over the stacks of lumber in various locations. However, because wood from For single-stack kilns, stationary fans are adequate. For all kiln drying schedules, a heater should be used to sterilize the lumber and kill any insects that may be present. I find that unplugging the DH is helpful during the sterilization phase so I can add a second heater, without overwhelming my electrical circuit. 73. Anyway, I included my log of a load I did in Nov '06 for everyone's amusement. Place some sample boards in the stack that will be easy to pull out for moisture testing later. 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. 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. Table 1 shows a typical drying schedule for sugar maple. This serves a dual purpose of supporting the rigid foam insulation as well as stiffening the floor framing. Take the electronics out of the kiln, and continue operating the heater and fans during this phase. Most species of hardwood lumber can be safely dried this way, once the moisture content is 20% to 25% or less. Select 3/4" conduit brackets for hanging baffles on 1/2" galvanized pipe. Basically, you dont want all of the air rushing out under the stack, so find a way to redirect it. Dehumidification Opportunities for Dehumidification Drying Of Hardwood Lumber Dimension Kiln Drying Hardwood Dimension Parts Discoloration Preventing Discolorations in Hardwood and Softwood Logs . Also check that air isnt escaping around the side baffles or under the stack of lumber. 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.) The Bolivian wood products industry was surveyed to determine lumber drying capacity, technology and. 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 you use a lot of lumber, and youre a decent hand at carpentry, a shed kiln will quickly pay for itself. Diy dehumidifier kiln time table. Equalizing and Conditioning USDA, 1991) . For the sterilization phase, air temperature needs to be around 140 F, for three to five hours. Omitting the sterilization phase can lead to costly losses from insect damage, so dont skip it. For all kiln drying schedules, a heater should be used to sterilize the lumber and kill any insects that may be present. Also check that air isnt escaping around the side baffles or under the stack of lumber. 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 . These are rough-saw red oak. Our capacities are 4,000 board feet in a kiln . In this system, moist air is not vented out of the kiln but is dehumidified, then recirculated . I'm trying to find a timetable or drying schedule for the basic dehumidification kilns you see on youtube. This, of course, is gross savings; we must calculate electrical costs to determine the net savings: in this case, about $62. Dehumidification Kiln Drying. I like these starter blocks to raise the lumber a few inches off the floor. A heavy-duty 1,500-watt space heater works fine. 0000001417 00000 n The delicate blue and white color scheme c Case hardening is a defect caused by the outer portion of a board drying quickly, while the inner portion dries more slowly. When properly loaded, this kiln can dry approximately 600 board feet of 4/4" lumber. This fact sheet summarizes the basics of kiln drying wood, the most commonly used methods, drying schedules and some drying defects. My shed kiln was stick-built from standard building material, and sized to take advantage of typical 4 x 8 sheet goods. This slows the end-grain drying and limits the severity of end checking. 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. _0e`bd\ p@ The last thing to do before starting the kiln is to close the gable vent with an insulated cover. At the planer mill, warped 2 by 4's represent a significant loss in value. 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. %3.3 Add to my manuals. In addition, weight on top of the stack can be helpful, but nothing replaces baffles for the best lumber yield. >> H6`2}s=n:l)CR>/"\ Appendix B . A higher humidity setting will run the unit sporadically to maintain that RH. Wood Shrink/Swell estimator - A web-based program to estimate shrink/ swell in wood. Dehumidification drying equipment is available, but an enclosure must be built to house the equipment and dry the lumber. Main thing is to not rush drying in first stages, as this will cause problems. 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. 2. Oregon-based HDE Dry Kilns has launched a new line of small kilns ranging from 2,000 to 12,000 board feet. 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. In addition, weight on top of the stack can be helpful, but nothing replaces baffles for the best lumber yield. 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. As you can recycle . Not bragging or anything! Kiln drying normally involves temperatures in the range of 40-75 C (about 100-170 F). 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 Enter the email address you signed up with and we'll email you a reset link. Such temperatures are high enough to kill insectsanother advantage of kiln drying over air drying. Consider the weight of the lumber that will be placed in the structure and fortify the building accordingly. Additionally, I have been underwhelmed by the performance of solar-operated fans. I have constructed a kiln using these plans. Dehumidification dry kilns operate at lower drying temperatures (typically below 150F) than do conventional kilns, which results in longer drying schedules. Dehumidification Kilns Many regions have increased the shed and outbuilding maximum allowable size without need for a permit. 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. There are two ways to remove water from the DH unit, and they both work well. My aim was to develop a small dehumidification kiln for better control of the three key components of lumber drying: temperature, airflow and humidity. 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 . Kiln drying is usually preceded by air drying to bring the moisture content of the wood down below 30%. This lets the operator sort stacks by lumber species, so they will be easy to retrieve when the drying cycle is complete. I cannot stress the importance of baffles enough. Built properly, a shed kiln may even increase the value of a property. An official website of the United States government. 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. The lumber was then measured for crook, bow, and twist. Another common sticker size is 1" x 2", and these work fine as well. I hope that the sawyer coated the ends of the lumber with Anchor-Seal or oil-based paint when it was green. The approach described in the article where you try to keep the water leaving at a steady rate is fine. Joining end grain to long grain forms the king of joints. In larger kilns, the heater may be needed in the latter part of the drying cycle. Most species of hardwood lumber can be safely dried this way, once the moisture content is 20% to 25% or less. The starter blocks should be as long as the stack is wide. This helps keep the lumber straight during the drying cycle; in fact, improper placement of stickers can permanently deform lumber. 7. After two days operating only the fans and DH, I take note of the temperature. A dehumidification kiln continuously recycles the heat throughout the chamber, rather than . Both restrained and control boards were dried to approximately 9 percent moisture content, representative of final in-service condi- tions. Forum Responses Remove samples from the stack, and cut an inch or two off one end. For a kiln temperature of 140 F, sterilization takes three to five hours. Then, write down the appropriate MC ranges (determined in #2 above) in the second column. My kiln uses four ceiling-mounted fans, each rated for 1,600 CFM. This will allow the heater to cycle on and off automatically, according to the kiln operators setting. The T-bars are made from 1/2" galvanized pipe and are attached to the rafters with threaded pipe flanges. 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. 0000001208 00000 n This would allow a stack of lumber four feet wide and 10 feet long. Wood Drying/ Seasoning. Sticker spacing can be increased to 24" apart for 5/4 or thicker hardwood. Delete from my manuals. /Width 1628