Kiln drying is usually preceded by air drying to bring the moisture content of the wood down below 30%. This allows for a more gentle kiln schedule to fully dry the timber. 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 . In exchange for building the shed myself, I wound up with a shed of higher quality, with more features. BE CAREFUL--The first temperature value must be repeated for every MC class (column #2) that is above 30% MC. Corrosion resistant epoxy coated aluminum cabinets and specially coated dehumidification coils for an extra long life. 6 0 obj Equalizing and conditioning are required for almost all hardwood lumber. 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. From contributor D: Nyle Systems dehumidification kiln packages are our best known product with nearly unlimited drying capabilities. Then align each subsequent layer of stickers over the last. 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. 0000001186 00000 n Remove samples from the stack, and cut an inch or two off one end. The velocity through the load is assumed to be between 275 and . Vacuum Kiln Drying. With a 130 F kiln temperature, sterilization will take 10 to 12 hours ( Dry Kiln Operators Manual, 1991 ). Main thing is to not rush drying in first stages, as this will cause problems. Dehumidification kilns from Nyle Systems in Brewer, Maine. A better choice might be a solar kiln, as you can dry wood from "wet" to 6-8 percent MC in 6-8 weeks. 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. Attic fans are a perfect way to provide airflow over the stacks of lumber. 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. Adjust the baffles or fan direction to achieve good airflow. The Bolivian wood products industry was surveyed to determine lumber drying capacity, technology and. (116 C) temperature. I was hoping someone could point me in the right direction or share experience. JavaScript seems to be disabled in your browser. . The stickers are uniform in size and usually 3/4 or 1 square. Dr. Gene Wengert provides schedules for kiln drying hardwood lumber. End baffles are also a good idea to prevent airflow from bypassing the stack entirely. Typical dehumidification kiln (FPL 1999 p. 12-10). 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. I know mixed loads are taboo, but this one worked well, other than the horse chestnut. However, if you kiln dry hardwood lumber that has already been air dried, the process is much more forgiving. Wood poles subjected to a 22- to 34-day dehumidification kiln schedule with a heat treatment to 60C to the poles' core. 0 Once all the lumber is stacked and stickered, place baffles over the lumber. If MC readings still arent at the desired range, the heat may need to be increased for the remainder of the drying cycle. A locked padlock 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 After two days operating only the fans and DH, I take note of the temperature. The stickers are uniform in size and usually 3/4" or 1" square. In this paper, the effective schedules were further investigated for longer culm parts treated with boron. 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 . In contrast, a dehumidification kiln uses a sealed chamber, with only enough energy input to maintain the desired temperature. Gen. Tech. The moisture loss, drying time and drying defects were determined. I recently picked up a back issue of American Woodworker, #94 June 2002, that has a good article on constructing a simple DH kiln. The first load was started with 60% and this load was started with 78%. In vacuum kiln trials, logs were heated to 56C at 70 percent log radius depth and the temperature maintained for . 3. Subtract the wet-bulb depression from the dry-bulb temperatures for each schedule step and enter the value in the fifth column. By. Once the core readings are 6% to 8% on a fresh cut, the lumber is dry and ready for sterilization. For a kiln temperature of 140 F, sterilization takes three to five hours. Enter the email address you signed up with and we'll email you a reset link. In addition, wood can be dried by special methods that include solar drying (use of greenhouse-type dryers or those equipped with solar collectors . The conversion method described in the Dry Kiln Operator's Manual is not really accurate, but it is safe. What can you do to speed up drying time? Created and Presented by: Henco Viljoen and Elijah McCarty with Nyle Dry Kilns. Thus, a drying program can be adapted according to the characteristics of the kiln load, e.g., species, dimensions, and moisture content. Unlike general shop space, bigger is not always better for kiln design. After seven to 10 days, I reverse the fan direction to make sure all stacks of lumber dry evenly. It should be double-pane, well-insulated with low emissivity (low-E). The T-bars are made from 1/2 galvanized pipe and are attached to the rafters with threaded pipe flanges. Using a piece of paper with 6 columns, write down the Schedule Step numbers in the first column on the left. Sign In Upload. Go to the second letter designation (the MC Class Designation) and find the corresponding MC ranges in the table below. 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 the operating conditions of this option are followed the material will meet the requirements of being kiln dried (KD) and heat treated . During the conditioning process, the only equipment operating are the fans, heater and the steam generator no dehumidifier. Appendix B . 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. Dehumidification drying system. HDE small kilns feature all-aluminum construction for a long, maintenance-free life span . Use the gridded drawings provided on the PDF, Woodworking | Blog | Videos | Plans | How To. For sterilizing thicker lumber, additional time is required. This procedure is discussed in a following section. Share sensitive information only on official, secure websites. This will allow the DH to drain automatically without you needing to enter the kiln. 9. Kiln drying lumber is a simple, cost effective method recommended for anyone who wants to increase profits by selling dried lumber. %PDF-1.6 % 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. Dehumidification Opportunities for Dehumidification Drying Of Hardwood Lumber Dimension Kiln Drying Hardwood Dimension Parts Discoloration Preventing Discolorations in Hardwood and Softwood Logs . An official website of the United States government. An outswing door can always be opened, regardless of shed contents. I recommend a 2 x 3 sliding window with bug screen. Remove samples from the stack, and cut an inch or two off one end. WOODWEB is a registered trademark of Woodweb.com. Different species should not be loaded simultaneously into the kiln due to often differing kiln schedules. 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. I hope that the sawyer coated the ends of the lumber with Anchor-Seal or oil-based paint when it was green. You can download the paper by clicking the button above. To accommodate the floor insulation, blocking between joists is oriented horizontally instead of the normal vertical position. 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.). 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. Thicker lumber like 5/4 or quartersawn lumber is naturally more stable. The common lumber name is used throughout. Abstract. Looking at the cost-benefit analysis of a shed kiln can be enlightening. 1. a furnace or oven for burning, baking, or drying, especially one for calcining lime or firing pottery. My question focuses on the initial relative humidity featured in the Safe Drying Rate table. 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.. Taking moisture away at the rate the board will "safely" part with it . If the temperature is below this range, I start the heater and adjust the thermostat accordingly. Attic fans are a perfect way to provide airflow over the stacks of lumber. Drying lumber too quickly can lead to deep end checking, warping and case hardening. Dehumidification dry kilns operate at lower drying temperatures (typically below 150F) than do conventional kilns, which results in longer drying schedules. . the Dry Kiln Operator's Manual (Simpson, 1991). 0000002536 00000 n Q,kjifT33P[! A discussion of how to apply "safe drying rate" calibrations with a home-built dehumidifying kiln. These figures hold true for lumber up to 2 thick. I cannot stress the importance of baffles enough. 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 . My baffles hang from T-bar assemblies mounted to the ceiling. A kiln schedule is a set of temperatures and humidities that are used during kiln operation. Schedules for several thicknesses and specialty products (e.g. 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. Soon the DH won't show much water collected in the tray. 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. Bring your moisture meter to confirm. Kiln Structure . 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. Select a heater with an adjustable thermostat and a tip-over shutoff. This serves a dual purpose of supporting the rigid foam insulation as well as stiffening the floor framing. Forum Responses When that is the case, I know Ill have usable lumber in just a few weeks. The schedules are all moisture content based, using the moisture content of the wettest half of the kiln samples. Ideally, a lumber kiln would be large enough to dry multiple stacks of lumber. This helps keep the lumber straight during the drying cycle; in fact, improper placement of stickers can permanently deform lumber. With advances in spray foam insulation, it may be possible to seal older, drafty structures as well. You can achieve top-quality results with incredible efficiency. My aim was to develop a small dehumidification kiln for better control of the three key components of lumber drying: temperature, airflow and humidity. Sticker spacing can be increased to 24" apart for 5/4 or thicker hardwood. /Width 1628 End baffles are also a good idea to prevent airflow from bypassing the stack entirely. The fact is, most of my stacks of lumber air dry to 15% moisture content before entering the kiln. Also, you can't really control well by measuring the collected water because some of the water leaks out with vented or leaking air. Dr. Gene Wengert provides schedules for kiln drying hardwood lumber. Be sure that all of the kiln equipment is working prop-erly before lumber is loaded into the kiln. My four main baffles consist of sheets of 1 Styrofoam insulation. Our approach was to build and operate a small dehumidification dry kiln. For the sterilization phase, air temperature needs to be around 140 F, for three to five hours. Consider not only the space for the lumber stacks, but extra floor space to easily load and monitor the charge of lumber. Drying lumber too quickly can lead to deep end checking, warping and case hardening. Temps are in Celsius (20C = 70F, 40C = 105F). For example, if you dry 7,500BF of fast drying Pine, you'd select the 8MBF chamber with the HT18 . I made a simple frame from plywood strips and attached the insulation sheets to them with screws and fender washers. Dehumidification Kiln Drying. HT systems use 40-60% less energy than gas-fired or steam dry kilns. 0000000710 00000 n Installing sheetrock and fire taping is a good idea for a heated room. This slows the end-grain drying and limits the severity of end checking. After seven to 10 days, I reverse the fan direction to make sure all stacks of lumber dry evenly. txN.a!HQ)FmCw~{B1Aq_!+zN#+j Dehumidification kiln schedules 145 Sterilizing, equalizing, and conditioning treatments 145 Sterilizing treatments 145 Mold 145 Fungal stain and decay 146 . If you use a lot of lumber, and youre a decent hand at carpentry, a shed kiln will quickly pay for itself. 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). A pre-hung steel exterior door is ideal in this situation, because it offers weatherstripping and is fully insulated. Most species of hardwood lumber can be safely dried this way, once the moisture content is 20% to 25% or less. The kiln climate is controlled by venting the hot air and replacing it with ambient air. Not bragging or anything! Construction of a kiln chamber is very similar to building a small house. Delete from my manuals. To hang the baffles, simply attach hooks to the plywood frame. The cost associated with shed construction was similar to buying a prefabricated kit. This will allow the heater to cycle on and off automatically, according to the kiln operators setting. 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. , , o* j=d An anemometer confirms that your effort constructing baffles was worthwhile. Kiln Systems. Should a Moulding Mill Bring Sawmill Operations In-House? The last thing to do before starting the kiln is to close the gable vent with an insulated cover. If you dry 9,500BF of slower drying Oak, youd use the 10MBF chamber with the HT8 Dehumidifier. . 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 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. The kiln schedule information in the tables below has been assembled from many different sources, including drying texts and industrial contacts. Low temperatures can be used for an extra safety margin on greener lumber. Should I? For all kiln drying schedules, a heater should be used to sterilize the lumber and kill any insects that may be present. A bead of silicone caulking between the subfloor and sill plate will prevent air infiltration. 0000004213 00000 n The baffles direct airflow over and through the stack and prevent the top layers from drying too quickly. hbbd``b` $ &UD\q@u For single-stack kilns, stationary fans are adequate. I cannot stress the importance of baffles enough. They are easy to use and give you precision control over your drying. Total costs for the materials were $2,704 based on 2006 prices. 282 0 obj <> endobj Changing the position of the doorway in various kiln setups helps provide the best access to the stacks of lumber. Regardless of size, allow for a 36 door that opens to a hallway of open space. 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). The four charges of lumber ranged from 600 to 700 board feet (bf), and a woodworker with no dry-kiln experience operated the kiln. Initially, I set the DH to 40% RH, because I dont want to remove moisture too quickly. . 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. This kicker board will help distribute the airflow more evenly through all layers of lumber. Secure .gov websites use HTTPS HWn8gXA N,[mKJr2"Ec9,t I often buy from sawyers or homeowners at 40% to 50% of retail price. Maderas. endstream endobj startxref H6`2}s=n:l)CR>/"\ Place some sample boards in the stack that will be easy to pull out for moisture testing later. The company's small kilns can be configured for drying lumber, firewood, or heat-treating lumber or wood packaging. However, you may need more cycles depending on the species, moisture content, and size of the timber. Dehumidification Kilns I chose double wall construction with 1/2 sheathing, and 1/2 T1-11 siding. This is because it needs to be dried to a lower moisture content than wood will air dry to outdoors. At the end of the cycle I have the opposite problem. Difficult-to-dry species might not exceed 60 C (140 F). Once the lumber is sterilized, it is ready for the conditioning phase. This makes lightweight baffles that can be easily moved and repositioned. Lay down the bead of caulking before raising the walls. I also wrapped the shed with Tyvek HomeWrap. I am removing water about 50% below the SDR. Wood drying (also seasoning lumber or wood seasoning) reduces the moisture content of wood before its use. 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. 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. Kiln dried wood typically sells for a third more than green lumber and eliminates the need for . The baffles direct airflow over and through the stack and prevent the top layers from drying too quickly. Each layer of lumber is separated from the next by a series of "stickers" or spacer sticks. This returns some moisture to the very dry exterior of the lumber, while not affecting the core moisture level. They are normally mounted in the gable of household attics, and they are designed to be used in high temperature environments. Each layer of lumber is separated from the next by a series of stickers or spacer sticks. Question The kiln humidity can be expressed as an EMC, relative humidity, or wet-bulb temperature. Equalizing and Conditioning There might be a problem with that if the chamber overheats and has to be vented because some water will leave that way. 6. With each load I did not have the initial relative humidity rate. Another great option is to convert an existing shed or outbuilding to a lumber kiln. I use a Rockler steam generator. Typical . This, of course, is gross savings; we must calculate electrical costs to determine the net savings: in this case, about $62. Frequently, the lumber has already air-dried for several years in a barn or outbuilding. All of these products were purchased at a local home center, except the remote hygrometer/thermometer which was purchased at a local electronics store. %3.3 Commercial scale steam kilns consume large amounts of energy. However, if you kiln dry hardwood lumber that has already been air dried, the process is much more forgiving. These figures hold true for lumber up to 2" thick. 3.24 solar-dehumidification drying kiln A small electric heater supplies auxiliary heat to maintain adequate kiln temperature. Size and placement of the access door are critical as well. /Name /ImagePart_0 This limits the amount of energy needed to bring lumber to the desired 6% to 8% moisture content. Featuring lower cost drying at speeds equal to gas & steam, these kilns are continuously exceeding industry standards and changing the game. The kiln operator sets the kiln controls based on the initial moisture of the lumber as it is loaded into the kiln. Culm parts with 2.0 and 2.2 m length after pressure treatment were dried in industrial kilns using three schedules with mild, severe and highly severe drying intensity. Minus the drying equipment, a shed kiln is just an insulated storage space, with a host of possible uses. hTn8>_l7h.&E:Bem=C9n\8]lMPc. hb```[@9p(T-3jO:g)@S 4Y]g7l\V!c!$Bf J B@&xcEz8PH@ZHs1/X$qOq,x'x$0.rWg*d XAT10 );9 /Filter /JBIG2Decode The second most common type of drying is called dehumidification drying. That purchase was an average deal, and one I dont consider a particular bargain. Y}-m+'@DQ4\h8GP]y@ yL. 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. Khmer Kiln: quite similar to the Anagama kiln however, traditional Khmer Kilns had a flat roof. Wood Shrink/Swell estimator - A web-based program to estimate shrink/ swell in wood. Kiln schedules are completely assembled and written out for easy use. This gives me a secondary method of tracking the drying process, using both water volume and moisture content (MC) readings. You may also return purchases to a Rockler store near you for store credit. Chinese, Korean or Japanese kilns have an arch roof. Rep. FPL-GTR-57. Basically, you don't want all of the air rushing out under the stack, so find a way to redirect it. USDA, 1991) . In the third column, write down the appropriate dry-bulb temperatures. In Fig. 0000001417 00000 n (Sawing and Drying Forum) . Rocky Mountain . 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 . Many regions have increased the shed and outbuilding maximum allowable size without need for a permit.
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