dehumidification kiln drying schedules

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. In smaller kilns, the heat generated by the fans and DH motor is sufficient to maintain temperatures in excess of 100 degrees. Just walk out to the shed kiln and grab what you need from your custom-dried supply. The stickers are uniform in size and usually 3/4 or 1 square. A higher humidity setting will run the unit sporadically to maintain that RH. 3.24 solar-dehumidification drying kiln Enter the email address you signed up with and we'll email you a reset link. Can also be used on any mobile device! A bead of silicone caulking between the subfloor and sill plate will prevent air infiltration. KD150 Series dehumidifier pdf manual download. A Checklist for Operators of Small Dry Kilns A companion to A Start-up Guide for Operators of Small Dry Kilns (FOR-132) Terry Conners, Forestry and Natural Resources /Filter /JBIG2Decode stream Unfortunately, little information is available regarding lumber drying technology and practices used, which is essential for the formulation of improvement strategies. My number one priority was to build a kiln that was easy to load and easy to monitor. 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. The kiln humidity can be expressed as an EMC, relative humidity, or wet-bulb temperature. A pre-hung steel exterior door is ideal in this situation, because it offers weatherstripping and is fully insulated. The KD150 Dehumidification Kiln Kit is a compact, entry-level dehumidification kiln for drying lumber between 300 and 1000 board feet. Loading the kiln begins by rousing my sons and letting them know Ive planned a day of work. For end baffles, I use 2-thick rigid foam insulation screwed to the main baffles. Schedules. Minus the drying equipment, a shed kiln is just an insulated storage space, with a host of possible uses. My baffles hang from T-bar assemblies mounted to the ceiling. -. The baffles do not need insulating properties, and plywood would work just as well. After four days, I decrease the RH setting on the DH to 30% and continue to run the fans. The store will not work correctly in the case when cookies are disabled. 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 0 3.) The DH is not needed at this time, as the lumber is already bone-dry. Schedule for drying 4/4 and 5/4 upland red oak in a steam dry kiln. Once the flooring deck is constructed, think about sealing the shed framing at every opportunity. If MC readings still arent at the desired range, the heat may need to be increased for the remainder of the drying cycle. 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. Lock The kiln schedule information in the tables below has been assembled from many different sources, including drying texts and industrial contacts. Also, you can't really control well by measuring the collected water because some of the water leaks out with vented or leaking air. %PDF-1.4 % . 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. Delete from my manuals. 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.). To condition the lumber, I introduce steam into the kiln for about two hours. 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. This gives me a secondary method of tracking the drying process, using both water volume and moisture content (MC) readings. . Typical dehumidification kiln (FPL 1999 p. 12-10). This will allow the heater to cycle on and off automatically, according to the kiln operator's setting. 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? November 1, 2020. Place a sticker at each end, and every 16" along the stack for 4/4 stock. Operates at a temperature range from 80F - 160F (26 - 71C). Additionally, I have been underwhelmed by the performance of solar-operated fans. Rocky Mountain . You can download the paper by clicking the button above. 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 . When the drying is done in a kiln, the product is known as kiln-dried timber or lumber, whereas air drying is the more traditional method.. Hardwood lumber kiln drying schedules typically keep the dry bulb temperature below 180 F (82 C). Wood poles subjected to a 22- to 34-day dehumidification kiln schedule with a heat treatment to 60C to the poles' core. (Note: This letter designation is related to the green MC of the species. This returns some moisture to the very dry exterior of the lumber, while not affecting the core moisture level. Typical . /Name /ImagePart_0 I either use some cedar 3" x 5", or 4" x 4" stock. Another common sticker size is 1" x 2", and these work fine as well. With each load I did not have the initial relative humidity rate. My four main baffles consist of sheets of 1" Styrofoam insulation. Always use adequate samples representing both the wettest and driest lumber in the dryer. 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. As a result, the kiln schedules were too severe. Madison, WI: U.S. Department of Agriculture, Forest Service, Forest Products Laboratory. 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. Always avoid conditions that add moisture back to the lumber, especially during start-up. A locked padlock Manufacturer guarantees/warranties for power tools, CNC and laser products will supersede the Rockler Guarantee if these items are damaged or defective. Then align each subsequent layer of stickers over the last. 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 DH is not needed at this time, as the lumber is already bone-dry. Ciencia y Tecnologia, Duygu Kocaefe, Ayhan Aytin, The Bolivian secondary forest products industry has experienced substantial growth during the last 10 years. JavaScript seems to be disabled in your browser. I also wrapped the shed with Tyvek HomeWrap. For all kiln drying schedules, a heater should be used to sterilize the lumber and kill any insects that may be present. Detailed design and custom manufacture of dehumidification and chiller systems for food processing, lumber drying and industrial applications. Particularly, important investment has taken place in lumber drying capacity. 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. For single-stack kilns, stationary fans are adequate. In the third column, write down the appropriate dry-bulb temperatures. This fact sheet summarizes the basics of kiln drying wood, the most commonly used methods, drying schedules and some drying defects. Kiln drying is the process of drying wood in a controlled environment, where temperature, air circulation and humidity are monitored and stabilized. I have constructed a kiln using these plans. Thicker lumber like 5/4 or quartersawn lumber is naturally more stable. Dehumidification kilns are similar to other kilns in basic construction and drying times are usually comparable. Subtract the wet-bulb depression from the dry-bulb temperatures for each schedule step and enter the value in the fifth column. Go to the second number designation (the wet-bulb depression designation) and find the corresponding depressions in the table below. For these reasons, I feel it is best to let the shed breathe, and forgo a plastic vapor barrier. 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. Dehumidification Kilns These figures hold true for lumber up to 2" thick. The schedules are all moisture content based, using the moisture content of the wettest half of the kiln samples. Each layer of lumber is separated from the next by a series of stickers or spacer sticks. These well-known dehumidification kiln packages have been among our bestselling products for the past 30 years. 4. So, with that lengthy introduction, here is my question. Dehumidification Opportunities for Dehumidification Drying Of Hardwood Lumber Dimension Kiln Drying Hardwood Dimension Parts Discoloration Preventing Discolorations in Hardwood and Softwood Logs . Go to the second letter designation (the MC Class Designation) and find the corresponding MC ranges in the table below. Whether to Wax Walnut Ends Before Steaming, Frequently Asked Questions about Widebelt Sanders. For a kiln temperature of 140 F, sterilization takes three to five hours. 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. This problem is magnified if the lumber is thin or flatsawn. WOODWEB is a registered trademark of Woodweb.com. Electrical requirements for a DIY kiln are pretty straightforward, but hiring an electrician is still a good idea. 3. Corners where walls meet should be sealed with expanding foam sealant. The T-bars are made from 1/2" galvanized pipe and are attached to the rafters with threaded pipe flanges. By setting the relative humidity (RH) on the dehumidifier, you can control how often it runs. I made a simple frame from plywood strips and attached theinsulation sheets to them with screws and fender washers. 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. Any small building could work, as long as it has a minimum of 2 x 4 framing, and will seal out unwanted air. After two days operating only the fans and DH, I take note of the temperature. I often buy from sawyers or homeowners at 40% to 50% of retail price. 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. - Model L300, L500, L1200-S Series - Medium Dehumidification Dry. I'm trying to find a timetable or drying schedule for the basic dehumidification kilns you see on youtube. Both restrained and control boards were dried to approximately 9 percent moisture content, representative of final in-service condi- tions. Corrosion resistant epoxy coated aluminum cabinets and specially coated dehumidification coils for an extra long life. Hardwood kiln drying schedules typically keep the dry bulb temperature below 80 C (176 F). Maderas. 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. My kiln uses four ceiling-mounted fans, each rated for 1,600 CFM. Size and placement of the access door are critical as well. Basically the idea seems to be to maintain a constant temperature, and . For sterilizing thicker lumber, additional time is required. A kiln schedule is a set of temperatures and humidities that are used during kiln operation. Then, write down the appropriate MC ranges (determined in #2 above) in the second column. The approach described in the article where you try to keep the water leaving at a steady rate is fine. I then manually rotate the fan boxes halfway through the drying cycle. Also, for that approach to work, the chamber needs to be air tight. For the best experience on our site, be sure to turn on Javascript in your browser. They are easy to use and give you precision control over your drying. I made a simple frame from plywood strips and attached the insulation sheets to them with screws and fender washers. Different species should not be loaded simultaneously into the kiln due to often differing kiln schedules. I found that brackets for mounting rigid metal electrical conduit work best. I prefer to empty the water tray manually and record the volume of water collected. For example, if you dry 7,500BF of fast drying Pine, you'd select the 8MBF chamber with the HT18 . 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. Choosing a Kiln Schedule /Width 1628 Nyle Systems dehumidification kiln packages are our best known product with nearly unlimited drying capabilities. kiln/. End baffles are also a good idea to prevent airflow from bypassing the stack entirely. Schedules for several thicknesses and specialty products (e.g. 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 . The velocity through the load is assumed to be between 275 and . 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. On this order alone, I saved over $1,300 by drying the lumber myself. These kilns will typically hold several thousand board foot of lumber. building the dehumidification dry kiln. Using a piece of paper with 6 columns, write down the Schedule Step numbers in the first column on the left. After seven to 10 days, I reverse the fan direction to make sure all stacks of lumber dry evenly. I like these "starter blocks" to raise the lumber a few inches off the floor. 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. Job Opportunities and Woodworking Services, Dust Collection, Safety and Plant Operation. 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. The fact is, most of my stacks of lumber air dry to 15% moisture content before entering the kiln. 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. A shed kiln is an attractive alternative for a couple of reasons. Should I? I am removing water about 50% below the SDR. 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). Among dimension lumber, the 2- by 4-inch size is typically the most susceptible to warp for a variety of reasons. For all kiln drying schedules, a heater should be used to sterilize the lumber and kill any insects that may be present. I hope that the sawyer coated the ends of the lumber with Anchor-Seal or oil-based paint when it was green. 0000006297 00000 n Kiln Structure . 158 p. Dry kiln schedules for commercial woods : temperate and tropical. A higher humidity setting will run the unit sporadically to maintain that RH. With a 130 F kiln temperature, sterilization will take 10 to 12 hours (Dry Kiln Operators Manual, 1991). Sears Canada 70 Pint Dehumidifier. (I have found that remotely monitoring the temperature and humidity with a WiFi sensor can be very helpful. the Dry Kiln Operator's Manual (Simpson, 1991). I use a Rockler steam generator. The conversion method described in the Dry Kiln Operator's Manual is not really accurate, but it is safe. Consider the weight of the lumber that will be placed in the structure and fortify the building accordingly. I find that unplugging the DH is helpful during the sterilization phase so I can add a second heater, without overwhelming my electrical circuit. The starter blocks should be as long as the stack is wide. Take the electronics out of the kiln, and continue operating the heater and fans during this phase. Reweigh and obtain the oven dry weight. Once the core readings are 6% to 8% on a fresh cut, the lumber is dry and ready for sterilization. An outswing door can always be opened, regardless of shed contents. Question Dont even think of powering your kiln with an extension cord. Dehumidification Kilns Our approach was to build and operate a small dehumidification dry kiln. 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 Attic fans are a perfect way to provide airflow over the stacks of lumber. Insulate the floor with 2 rigid foam for convenience and durability. Featuring lower cost drying at speeds equal to gas & steam, these kilns are continuously exceeding industry standards and changing the game. 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). trailer << /Size 918 /Info 891 0 R /Root 907 0 R /Prev 482770 /ID[<67858f68421814977b05bc7913f6cc23><4073af979fbabe8f1c016146fd1c21ef>] >> startxref 0 %%EOF 907 0 obj << /Pages 902 0 R /Type /Catalog /DefaultGray 903 0 R /DefaultRGB 904 0 R /Metadata 905 0 R >> endobj 916 0 obj << /S 499 /Filter /FlateDecode /Length 917 0 R >> stream Remove samples from the stack, and cut an inch or two off one end. This serves a dual purpose of supporting the rigid foam insulation as well as stiffening the floor framing. The sheetrock also helps to protect the fiberglass insulation. For example, if you dry 7,500BF of fast drying Pine, youd select the 8MBF chamber with the HT18 Dehumidifier. A free BASIC program to convert the designations into actual temperatures and humidities is available from the author. This, of course, is gross savings; we must calculate electrical costs to determine the net savings: in this case, about $62. T8-C3 or similar for hard maple), the article instead provided a table showing the "safe drying rates" (SDR) for a number of species. 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. 0000001186 00000 n 4.4 drying schedule moisture content drying schedule . /ColorSpace /DeviceGray A maximum 45 F depression often produces better lumber. I selected a 36 outswing exterior door. 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. Basically, you dont want all of the air rushing out under the stack, so find a way to redirect it. Another reason I like the idea of a shed kiln is the flexibility of future use. Usually, you need anywhere between five to eight kiln schedules to complete the process. The following tables show some examples of oak schedules for steam dry kilns and dehumidification dryers. 10. This prevents dead spots inside the chamber that experience limited airflow. Wood drying (also seasoning lumber or wood seasoning) reduces the moisture content of wood before its use. In this system, moist air is not vented out of the kiln but is dehumidified, then recirculated . A lower RH setting will call for the DH to run more often. I hope that the sawyer coated the ends of the lumber with Anchor-Seal or oil-based paint when it was green. Contractors work on a tight schedule, and that may not allow much time for curing and drying concrete. The schedule designations use the popular U.S. Forest Products Laboratory designations. Check out More On the Web for my complete calculations to figure savings. Kiln Systems. The first thing to consider when designing a shed kiln is size. Such temperatures are high enough to kill insectsanother advantage of kiln drying over air drying. The last thing to do before starting the kiln is to close the gable vent with an insulated cover. Low temperatures can be used for an extra safety margin on greener lumber. Also check that air isnt escaping around the side baffles or under the stack of lumber. Wood-Mizer dehumidification and solar wood kilns range from 300 to 35,000 board feet capacity for drying lumber. Another common sticker size is 1 x 2, and these work fine as well. 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. My four main baffles consist of sheets of 1 Styrofoam insulation. For all kiln drying schedules, a heater should be used to sterilize the lumber and kill any insects that may be present. To browse Academia.edu and the wider internet faster and more securely, please take a few seconds toupgrade your browser. This plan allows . In this research, a drying restraint system was evaluated as a means of warp reduction in 8- and 16-foot-long SYP lumber. Check your local building codes for regionally specific requirements and electrical permits. A lazy Susan with 180 detents mounts the fan box to the ceiling. Vacuum Kiln Drying. Looking at the cost-benefit analysis of a shed kiln can be enlightening. This will allow the heater to cycle on and off automatically, according to the kiln operators setting. If you cannot find exact match, look at SG of same family species. . Main thing is to not rush drying in first stages, as this will cause problems. The air flow rate through your stacks should be about 350FPM. %PDF-1.5 Air speed of 350 feet per minute is appropriate for common hardwoods such as oak and maple. End baffles are also a good idea to prevent airflow from bypassing the stack entirely. I am using a household . Insulation for walls and ceilings should be a minimum of R13. 0000002827 00000 n 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. (I have found that remotely monitoring the temperature and humidity with a WiFi sensor can be very helpful. You can achieve top-quality results with incredible efficiency. The second most common type of drying is called dehumidification drying. Kiln schedules are completely assembled and written out for easy use. 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. 7. Place some sample boards in the stack that will be easy to pull out for moisture testing later. Construction of a kiln chamber is very similar to building a small house. 0000002536 00000 n Then align each subsequent layer of stickers over the last. This prevents "dead spots" inside the chamber that experience limited airflow. Most species of hardwood lumber can be safely dried this way, once the moisture content is 20% to 25% or less. Its a nice use of technology and adds a measure of safety as well.)