In this research, a drying restraint system was evaluated as a means of warp reduction in 8- and 16-foot-long SYP lumber. Once the core readings are 6% to 8% on a fresh cut, the lumber is dry and ready for sterilization. The kiln configuration and a drying schedule can be input and the code in the Excel file will simulate . 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. With a 130 F kiln temperature, sterilization will take 10 to 12 hours ( Dry Kiln Operators Manual, 1991 ). Exterior sheathing and siding type also factors into the heat-holding ability of the structure. Insulation for walls and ceilings should be a minimum of R13. -. 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. In smaller kilns, the heat generated by the fans and DH motor is sufficient to maintain temperatures in excess of 100 degrees. Corners where walls meet should be sealed with expanding foam sealant. Take a moisture reading in the end grain with a pin-type moisture meter or remote probe. Vote. The kiln schedule information in the tables below has been assembled from many different sources, including drying texts and industrial contacts. The four charges of lumber ranged from 600 to 700 board feet (bf), and a woodworker with no dry-kiln experience operated the kiln. 2. My aim was to develop a small dehumidification kiln for better control of the three key components of lumber drying: temperature, airflow and humidity. HT systems use 40-60% less energy than gas-fired or steam dry kilns. Reply. They are easy to use and give you precision control over your drying. 0000006297 00000 n Lock Another reason I like the idea of a shed kiln is the flexibility of future use. Insulate the floor with 2 rigid foam for convenience and durability. 0 Sears Canada 70 Pint Dehumidifier. Instead of using expensive electrically reversible fans designed for commercial kilns, I came up with a simple hardware solution. 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. An anemometer confirms that your effort constructing baffles was worthwhile. Go to the second letter designation (the MC Class Designation) and find the corresponding MC ranges in the table below. Its a nice use of technology and adds a measure of safety as well.) Diy dehumidifier kiln time table. If required, look-up and write down the RH (sixth column) and EMC (seventh column) for each schedule step. Kiln Structure . This gives me a secondary method of tracking the drying process, using both water volume and moisture content (MC) readings. On the last load of lumber I purchased, I saved $2.50 per board foot compared to retail prices for kiln-dried lumber. Thus, a drying program can be adapted according to the characteristics of the kiln load, e.g., species, dimensions, and moisture content. Know how to choose and apply the correct schedule for the lumber. The second most common type of drying is called dehumidification drying. Wood drying (also seasoning lumber or wood seasoning) reduces the moisture content of wood before its use. In-service replacement of warped 2 by 4's as wall studs or truss members is costly. A dehumidification kiln continuously recycles the heat throughout the chamber, rather than . Using a Kiln Schedule As you can recycle . Rocky Mountain . Sorry, preview is currently unavailable. Additionally, I have been underwhelmed by the performance of solar-operated fans. Sticker spacing can be increased to 24" apart for 5/4 or thicker hardwood. Kiln dried wood typically sells for a third more than green lumber and eliminates the need for . I am using a household . Dehumidification drying system. 0000001186 00000 n the hardwood kiln schedule is the equalization of the moisture content of all boards at 6-8%. A shed kiln has minimal venting (usually one or two gable vents) and sealed soffits. . /Width 1628 Joining end grain to long grain forms the king of joints. There are two ways to remove water from the DH unit, and they both work well. 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. I then manually rotate the fan boxes halfway through the drying cycle. Basically, you don't want all of the air rushing out under the stack, so find a way to redirect it. This kicker board will help distribute the airflow more evenly through all layers of lumber. In addition, weight on top of the stack can be helpful, but nothing replaces baffles for the best lumber yield. Also check that air isnt escaping around the side baffles or under the stack of lumber. Usually, you need anywhere between five to eight kiln schedules to complete the process. Also check that air isnt escaping around the side baffles or under the stack of lumber. This would allow a stack of lumber four feet wide and 10 feet long. I recently picked up a back issue of American Woodworker, #94 June 2002, that has a good article on constructing a simple DH kiln. 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. The lumber was then measured for crook, bow, and twist. Installing a window in a kiln may seem counterintuitive at first, because windows lose more heat than an insulated wall. Official websites use .gov Contractors work on a tight schedule, and that may not allow much time for curing and drying concrete. Then align each subsequent layer of stickers over the last. This can create internal stress in the lumber that is released when sawing. Enter the email address you signed up with and we'll email you a reset link. The DH is not needed at this time, as the lumber is already bone-dry. Determine the equalization settings and conditioning settings, as required. The schedules can also be formulated manually as follows. 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. Formulating a Kiln Schedule These well-known dehumidification kiln packages have been among our bestselling products for the past 30 years. This air space is absolutely critical for even airflow, so count on the extra floor space right from the design phase. Main thing is to not rush drying in first stages, as this will cause problems. If severe enough, the lumber can develop honeycomb cracks throughout. Remove samples from the stack, and cut an inch or two off one end. With a 130 F kiln temperature, sterilization will take 10 to 12 hours (Dry Kiln Operators Manual, 1991). Take the electronics out of the kiln, and continue operating the heater and fans during this phase. In Fig. Adjust the baffles or fan direction to achieve good airflow. Featuring lower cost drying at speeds equal to gas & steam, these kilns are continuously exceeding industry standards and changing the game. If you cannot find exact match, look at SG of same family species. Schedules Dry Kiln Schedules for Commercial Woods Do not know just how the end point of moisture would compare. (A major source was Dry Kiln Schedules for Commercial Woods which is available from the Forest Products Society in Madison, WI.) Standard kiln drying temperatures are low - around 120 degrees Fahrenheit or so, and drying times vary by wood size and moisture level. . Hardwood lumber kiln drying schedules typically keep the dry bulb temperature below 180 F (82 C). Place a sticker at each end, and every 16" along the stack for 4/4 stock. Measure airflow over the stacks of lumber in various locations. I hope that the sawyer coated the ends of the lumber with Anchor-Seal or oil-based paint when it was green. Should I? (Sawing and Drying Forum) Conventional kiln 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 Unfortunately, little information is available regarding lumber drying technology and practices used, which is essential for the formulation of improvement strategies. Regardless of size, allow for a 36 door that opens to a hallway of open space. Basically the idea seems to be to maintain a constant temperature, and . H6`2}s=n:l)CR>/"\ Secure .gov websites use HTTPS Both restrained and control boards were dried to approximately 9 percent moisture content, representative of final in-service condi- tions. >> Another great option is to convert an existing shed or outbuilding to a lumber kiln. However, the natural light and ventilation offered by a small window outweighs any disadvantages. Another common sticker size is 1" x 2", and these work fine as well. The baffles do not need insulating properties, and plywood would work just as well. 282 0 obj <> endobj Commercial scale steam kilns consume large amounts of energy. At the end of the cycle I have the opposite problem. When that is the case, I know Ill have usable lumber in just a few weeks. The kiln humidity can be expressed as an EMC, relative humidity, or wet-bulb temperature. HDE small kilns feature all-aluminum construction for a long, maintenance-free life span . Our approach was to build and operate a small dehumidification dry kiln. All of these products were purchased at a local home center, except the remote hygrometer/thermometer which was purchased at a local electronics store. The last step requires a short period of high humidity to relieve the drying stresses in the boards. 4.4 drying schedule moisture content drying schedule . 44. Would adding humidity at the start, bringing the initial relative humidity rate to 87% as suggested in the table, result in better product or faster drying? A small "m" after the designation indicates that the wet-bulb temperatures should be adjusted to avoid temperatures below 90 F. See the above mentioned publication for details. Changes in kiln temperatures and humidities are based on the MC of the lumber being dried, which in turn is determined from properly prepared kiln samples. If the fans and dehumidifer generate enough heat to maintain a temperature of 100 to 120 F, then I wont use the auxiliary heater. I hope that the sawyer coated the ends of the lumber with Anchor-Seal or oil-based paint when it was green. 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 My kiln schedule starts with running all fans and the dehumidifier for two days, measuring and removing water as it accumulates. 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. (See the following sections for a discussion of how to develop a schedule from these designations.) By. hTn8>_l7h.&E:Bem=C9n\8]lMPc. %PDF-1.6 % Once the core readings are 6% to 8% on a fresh cut, the lumber is dry and ready for sterilization. Moisture Content Dry Bulb Wet Bulb Depression percent degree F degree F degree F Above 50 110 106 4 50 to 40 110 105 5 40 to 35 110 102 8 35 to 30 110 96 14 30 to 25 120 90 30 I've been drying hardwood lumber in this Sauno dehumidification kiln for 4 years with excellent results. When the operating conditions of this option are followed the material will meet the requirements of being kiln dried (KD) and heat treated . squares, handle stock, gunstock blanks) are given for many species. From contributor D: The order was 540 board feet (BF) of 5/4 white oak. Apply foil tape to the edges of the main baffles to help protect the Styrofoam. For more capacity, consider a two stack kiln (12 x 12), or a three-stack kiln (12 x 16). Electrical requirements for a DIY kiln are pretty straightforward, but hiring an electrician is still a good idea. I am removing water about 50% below the SDR. (116 C) temperature. Thicker lumber like 5/4 or quartersawn lumber is naturally more stable. Operates at a temperature range from 80F - 160F (26 - 71C). - Model L300, L500, L1200-S Series - Medium Dehumidification Dry. If you use a lot of lumber, and youre a decent hand at carpentry, a shed kiln will quickly pay for itself. . Taking moisture away at the rate the board will "safely" part with it . Then align each subsequent layer of stickers over the last. This will allow the heater to cycle on and off automatically, according to the kiln operators setting. 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. A low temperature heat treatment chamber and/or dehumidification kiln is identified as operating between approximately 43C (110F) and 56C (133F) for an extended period during the kiln drying cycle. 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. . %PDF-1.5 Air drying to 6 - 8% MC is a very long term proposition and I'm not a patient man so I wanted a means to finish dry lumber after air drying outside to the EMC of my area of around 12 - 14%. 6. USDA, 1991) . Wood Shrink/Swell estimator - A web-based program to estimate shrink/ swell in wood. I usually see a large volume of water in the DH each night when I check the kiln. In this paper, the effective schedules were further investigated for longer culm parts treated with boron. Y}-m+'@DQ4\h8GP]y@ yL. The schedules are all moisture content based, using the moisture content of the wettest half of the kiln samples. For all kiln drying schedules, a heater should be used to sterilize the lumber and kill any insects that may be present. In smaller kilns, the heat generated by the fans and DH motor is sufficient to maintain temperatures in excess of 100 degrees. Many available kiln designs require a large, heavy door. For example, if you dry 7,500BF of fast drying Pine, youd select the 8MBF chamber with the HT18 Dehumidifier. A small electric heater supplies auxiliary heat to maintain adequate kiln temperature. 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. https://www.fs.usda.gov/research/treesearch/9635, International Institute of Tropical Forestry, Eastern Forest Environmental Threat Assessment Center, Northern Institute of Applied Climate Science, Western Wildland Environmental Threat Assessment Center, conventional-temperature (< 180 F) schedules, elevated-temperature (180-212 F) schedules, R. Sidney Boone, Charles J. Kozlik, Paul J. Bois, Eugene M. Wengert. Also, today, we are often kiln drying No.2 Common lumber which requires a milder schedule than upper grades; in the 1950s, seldom was this lower grade lumber kiln dried.) I modified one of the Radio Shack combo units so it could measure the RH remotely as well as the temp. Hardwood lumber kiln drying schedules typically keep the dry bulb temperature below 180 F (82 C). I found that brackets for mounting rigid metal electrical conduit work best. The delicate blue and white color scheme c In contrast, a dehumidification kiln uses a sealed chamber, with only enough energy input to maintain the desired temperature. The T-bars are made from 1/2 galvanized pipe and are attached to the rafters with threaded pipe flanges. A free BASIC program to convert the designations into actual temperatures and humidities is available from the author. This report contains suggested dry kiln schedules for over 500 commercial woods, both temperate and tropical. A lazy Susan with 180 detents mounts the fan box to the ceiling. Schedules. Also, for that approach to work, the chamber needs to be air tight. 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. Warp in dimension lumber is a significant cause for loss in grade and value. A heavy-duty 1,500-watt space heater works fine. It is a meaningless exercise to try to convert those schedules for the kiln you built. The problems with solar kilns include limited control over temperature and limited solar exposure, depending on your region and site location. My kiln uses four ceiling-mounted fans, each rated for 1,600 CFM. Whether to Wax Walnut Ends Before Steaming, Frequently Asked Questions about Widebelt Sanders. 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. As the MC drops and I crank the DH on more and more, the temp tends to rise up too high just from the heat the DH throws off, even though the light bulb heaters are not on at that point. January 27, 2007. Phytosanitary heat treatments of Ceratocystis lukuohia and Ceratocystis huliohia-colonized Metrosideros polymorpha wood were evaluated using kilns. This returns some moisture to the very dry exterior of the lumber, while not affecting the core moisture level. End baffles are also a good idea to prevent airflow from bypassing the stack entirely. noun: kiln; plural noun: kilns. Additionally, a 12 air plenum is required between the walls and stacks of lumber. Oregon-based HDE Dry Kilns has launched a new line of small kilns ranging from 2,000 to 12,000 board feet. Dehumidification Kiln. The remaining width allows for a 36-wide door and space for your drying equipment. 10. Kiln drying lumber is a simple, cost effective method recommended for anyone who wants to increase profits by selling dried lumber. I made a simple frame from plywood strips and attached the insulation sheets to them with screws and fender washers. 0000001417 00000 n My kiln uses four ceiling-mounted fans, each rated for 1,600 CFM. With each load I did not have the initial relative humidity rate. 3.24 solar-dehumidification drying kiln Anyway, I included my log of a load I did in Nov '06 for everyone's amusement. T8-C3 or similar for hard maple), the article instead provided a table showing the "safe drying rates" (SDR) for a number of species. Air speed of 350 feet per minute is appropriate for common hardwoods such as oak and maple. Initially, I set the DH to 40% RH, because I dont want to remove moisture too quickly. Check out More On the Web for my complete calculations to figure savings. I cannot stress the importance of baffles enough. 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. The first load was started with 60% and this load was started with 78%. For the best experience on our site, be sure to turn on Javascript in your browser. Looking at the cost-benefit analysis of a shed kiln can be enlightening. Select a heater with an adjustable thermostat and a tip-over shutoff. 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.gov website belongs to an official government However, you may need more cycles depending on the species, moisture content, and size of the timber. The fact is, most of my stacks of lumber air dry to 15% moisture content before entering the kiln. They are easy to use and give you precision control over your drying. Schedule for drying 4/4 and 5/4 upland red oak in a steam dry kiln. Each layer of lumber is separated from the next by a series of "stickers" or spacer sticks. Its a nice use of technology and adds a measure of safety as well.) This limits the amount of energy needed to bring lumber to the desired 6% to 8% moisture content. The schedule designations use the popular U.S. Forest Products Laboratory designations. As a result, the kiln schedules were too severe. Chinese, Korean or Japanese kilns have an arch roof. Appendix B . An outswing door can always be opened, regardless of shed contents. A maximum 45 F depression often produces better lumber. 1. a furnace or oven for burning, baking, or drying, especially one for calcining lime or firing pottery. << An anemometer confirms that your effort constructing baffles was worthwhile. 0 \ 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. Once the flooring deck is constructed, think about sealing the shed framing at every opportunity. Every Nyle Dehumidification Dry Kiln System Example: If the WBT falls below the set parameter measures and regulates internal kiln conditions the system will turn on the spray system. 0000003109 00000 n On this order alone, I saved over $1,300 by drying the lumber myself. Kiln drying is almost always essential for wood intended for interior uses. I selected a 36 outswing exterior door. For a kiln temperature of 140 F, sterilization takes three to five hours. This returns some moisture to the very dry exterior of the lumber, while not affecting the core moisture level. noun. Staff. With advances in spray foam insulation, it may be possible to seal older, drafty structures as well. For end baffles, I use 2-thick rigid foam insulation screwed to the main baffles. 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. With a 130 F kiln temperature, sterilization will take 10 to 12 hours ( Dry Kiln Operators Manual, 1991 ). Instead of using expensive electrically reversible fans designed for commercial kilns, I came up with a simple hardware solution.
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