Contractors work on a tight schedule, and that may not allow much time for curing and drying concrete. This helps keep the lumber straight during the drying cycle; in fact, improper placement of stickers can permanently deform lumber. (116 C) temperature. Then align each subsequent layer of stickers over the last. 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. I made a simple frame from plywood strips and attached the insulation sheets to them with screws and fender washers. WOODWEB is a registered trademark of Woodweb.com. Reweigh and obtain the oven dry weight. In exchange for building the shed myself, I wound up with a shed of higher quality, with more features. Vacuum Kiln Drying - Keenan Slab Works You can achieve top-quality results with incredible efficiency. After two days operating only the fans and DH, I take note of the temperature. It can be constructed in any style, with architectural features that match or complement an existing home. 2. 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? The kiln configuration and a drying schedule can be input and the code in the Excel file will simulate . Projects included design, construction, installation and commissioning of heat-pump based dehumidification equipment for seafood and fish gelatin products, hardwood lumber kilns and laboratory testing. Consider not only the space for the lumber stacks, but extra floor space to easily load and monitor the charge of lumber. I am also curious why an initial temperature of 90F would have been selected. in the kiln to dry specific wood products at a satisfactory rate without causing objectionable drying defects. Dehumidification Drying For Small Woodworking Firms and Hobbyists What can you do to speed up drying time? Most species of hardwood lumber can be safely dried this way, once the moisture content is 20% to 25% or less. PDF Kiln Schedules Chapter 7 If MC readings still arent at the desired range, the heat may need to be increased for the remainder of the drying cycle. You can achieve top-quality results with incredible efficiency. I then manually rotate the fan boxes halfway through the drying cycle. I then manually rotate the fan boxes halfway through the drying cycle. As you can recycle . Go to the first number designation (the temperature designation) and find the corresponding temperatures in the table below. A variety of wood drying kiln technologies exist today: conventional, dehumidification, solar, vacuum and radio frequency. I cannot stress the importance of baffles enough. If MC readings still arent at the desired range, the heat may need to be increased for the remainder of the drying cycle. On the last load of lumber I purchased, I saved $2.50 per board foot compared to retail prices for kiln-dried lumber. If you dry 9,500BF of slower drying Oak, youd use the 10MBF chamber with the HT8 Dehumidifier. Typical dehumidification kiln (FPL 1999 p. 12-10). Take a moisture reading in the end grain with a pin-type moisture meter or remote probe. Soon the DH wont show much water collected in the tray. hb```[@9p(T-3jO:g)@S 4Y]g7l\V!c!$Bf J B@&xcEz8PH@ZHs1/X$qOq,x'x$0.rWg*d XAT10 );9 When properly loaded, this kiln can dry approximately 600 board feet of 4/4" lumber. They are normally mounted in the gable of household attics, and they are designed to be used in high temperature environments. Wood Drying/ Seasoning. PDF Dry Kiln Schedules for Commercial Woods - Temperate and Tropical Drying lumber too quickly can lead to deep end checking, warping and case hardening. Using a dehumidifier for home made kiln? | Woodworking Talk ) or https:// means youve safely connected to the .gov website. Wood boiler for Lumber Kiln | Hearth.com Forums Home This can create internal stress in the lumber that is released when sawing. 1998. by Dr. Eugene Wengert. A maximum 45 F depression often produces better lumber. Lay down the bead of caulking before raising the walls. WOODWEB is a registered trademark of Woodweb.com. My kiln uses four ceiling-mounted fans, each rated for 1,600 CFM. Appendix B . Air speed of 350 feet per minute is appropriate for common hardwoods such as oak and maple. By setting the relative humidity (RH) on the dehumidifier, you can control how often it runs. The air flow rate through your stacks should be about 350FPM. The thinner the stock, the more critical sticker placement becomes. After seven to 10 days, I reverse the fan direction to make sure all stacks of lumber dry evenly. However, because wood from 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. I'm trying to find a timetable or drying schedule for the basic dehumidification kilns you see on youtube. Warp in dimension lumber is a significant cause for loss in grade and value. An official website of the United States government. Wood Shrink/Swell estimator - A web-based program to estimate shrink/ swell in wood. I have sensors in the kiln for moisture levels & probes in the center of the wood attached to a lignomat moisture meter. In larger kilns, the heater may be needed in the latter part of the drying cycle. Our approach was to build and operate a small dehumidification dry kiln. Low Temperature Kiln Drying Systems (120F) 300BF - 4000BF Capacity . Drying Wood With A Home Dehumidifier - LumberJocks The kiln humidity can be expressed as an EMC, relative humidity, or wet-bulb temperature. The stickers are uniform in size and usually 3/4 or 1 square. Recently, either Wood, or American Woodworker showed how to build a small version of a solar kiln. However, if you kiln dry hardwood lumber that has already been air dried, the process is much more forgiving. - Model L300, L500, L1200-S Series - Medium Dehumidification Dry. A.gov website belongs to an official government Also, since heat rises, ceiling-mounted fans have the added benefit of circulating the warmest air over the lumber. A household dehumidifier (DH) removes moisture from the kiln chamber. I usually see a large volume of water in the DH each night when I check the kiln. Dehumidification Kiln - Sawmill Creek Basically, you dont want all of the air rushing out under the stack, so find a way to redirect it. A better choice might be a solar kiln, as you can dry wood from "wet" to 6-8 percent MC in 6-8 weeks. Hardwood kiln drying schedules typically keep the dry bulb temperature below 80 C (176 F). 0000000591 00000 n Place a sticker at each end, and every 16" along the stack for 4/4 stock. 0000004213 00000 n Gen. Tech. Each layer adds approximately .81 R value. PDF Dehumidification Kiln Drying - Eri.nau.edu 14-foot Kiln dried red oak beams - timbers - lumber- Many other 1998. HT systems use 40-60% less energy than gas-fired or steam dry kilns. I had these custom cut and I air dried them outside under a tarp for 6 to 18 months (depending on which load they came in on) and then I kiln dried them in a Nyle dehumidification kiln for 3 months. In Fig. End baffles are also a good idea to prevent airflow from bypassing the stack entirely. "Safe Drying Rate" and a Dehumidifier Kiln - WOODWEB For more capacity, consider a two stack kiln (12 x 12), or a three-stack kiln (12 x 16). Once the core readings are 6% to 8% on a fresh cut, the lumber is dry and ready for sterilization. The stickers are uniform in size and usually 3/4" or 1" square. They are easy to use and give you precision control over your drying. With advances in spray foam insulation, it may be possible to seal older, drafty structures as well. A dehumidification kiln makes sense particularly when the lumber is air-dried first. Sorry, preview is currently unavailable. I have been reading & studying kiln schedules for years too. 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 For sterilizing thicker lumber, additional time is required. There are many types of kilns, but the most common are dehumidification kilns and conventional kilns. Once the flooring deck is constructed, think about sealing the shed framing at every opportunity. 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. These well-known dehumidification kiln packages have been among our bestselling products for the past 30 years. Kiln-Dried Wood | Everything You Need to Know in a Nutshell The baffles do not need insulating properties, and plywood would work just as well. Take a moisture reading in the end grain with a pin-type moisture meter or remote probe.) I modified one of the Radio Shack combo units so it could measure the RH remotely as well as the temp. The baffles direct airflow over and through the stack and prevent the top layers from drying too quickly. If you cannot find exact match, look at SG of same family species. The DH is not needed at this time, as the lumber is already bone-dry. 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 Our capacities are 4,000 board feet in a kiln . For the best experience on our site, be sure to turn on Javascript in your browser. 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. Difficult-to-dry species might not exceed 140 degrees F. Dehumidification kilns are very . A kiln schedule is a set of temperatures and humidities that are used during kiln operation. This listing incorporates current market requirements for the various species, as well as the current quality of the lumber resource itself. 7. Operation and cost of a small dehumidification dry kiln Chinese, Korean or Japanese kilns have an arch roof. This will allow the heater to cycle on and off automatically, according to the kiln operators setting. Diy dehumidifier kiln time table : r/woodworking - Reddit This limits the amount of energy needed to bring lumber to the desired 6% to 8% moisture content. Ideally, a lumber kiln would be large enough to dry multiple stacks of lumber. The kiln operator sets the kiln controls based on the initial moisture of the lumber as it is loaded into the kiln. 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. Place some sample boards in the stack that will be easy to pull out for moisture testing later. The order was 540 board feet (BF) of 5/4 white oak. My question focuses on the initial relative humidity featured in the Safe Drying Rate table. Difficult-to-dry species might not exceed 140 degrees F. Dehumidification kilns are very . I am using a household . 0000001208 00000 n If you use a lot of lumber, and youre a decent hand at carpentry, a shed kiln will quickly pay for itself. These well-known dehumidification kiln packages have been among our bestselling products for the past 30 years. Cost and operation of a Small dehumidification dry kiln - ResearchGate Without baffles, the top layers of lumber experience potato chipping with cupping, twisting or warping. %3.3 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. Kiln drying normally involves temperatures in the range of 40-75 C (about 100-170 F). Dr. Gene Wengert provides schedules for kiln drying hardwood lumber. Corners where walls meet should be sealed with expanding foam sealant. I chose double wall construction with 1/2 sheathing, and 1/2 T1-11 siding. Low temperatures can be used for an extra safety margin on greener lumber. My number one priority was to build a kiln that was easy to load and easy to monitor. There are two main reasons for drying wood: Woodworking When wood is used as a construction material, whether as a structural support in a building . 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. 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 . The kiln process involves the drying of wood in a chamber where air circulation, relative humidity and temperature can be controlled so that the moisture content of wood can be reduced to a target . A locked padlock A pre-hung steel exterior door is ideal in this situation, because it offers weatherstripping and is fully insulated. The company's small kilns can be configured for drying lumber, firewood, or heat-treating lumber or wood packaging. Wood drying (also seasoning lumber or wood seasoning) reduces the moisture content of wood before its use. For a single-stack kiln I recommend a minimum shed size of 8 x 12. This would allow a stack of lumber four feet wide and 10 feet long. For these reasons, I feel it is best to let the shed breathe, and forgo a plastic vapor barrier. This allows for a more gentle kiln schedule to fully dry the timber. I either use some cedar 3" x 5", or 4" x 4" stock. January 27, 2007. This problem is magnified if the lumber is thin or flatsawn. A lazy Susan with 180 detents mounts the fan box to the ceiling. Reply. I selected a 36 outswing exterior door. Rocky Mountain . 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.). There may be more depression values than required; ignore the extra depression values in this table. Take the electronics out of the kiln, and continue operating the heater and fans during this phase. During the conditioning process, the only equipment operating are the fans, heater and the steam generator no dehumidifier. With a 130 F kiln temperature, sterilization will take 10 to 12 hours (Dry Kiln Operators Manual, 1991). The sheetrock also helps to protect the fiberglass insulation. Inexpensive Dehumidification Kiln - YouTube I was hoping someone could point me in the right direction or share experience. A kiln schedule is a set of temperatures and humidities that are used during kiln operation. Thus, a drying program can be adapted according to the characteristics of the kiln load, e.g., species, dimensions, and moisture content. Building a dehumidifier wood kiln - part 1 - YouTube Additionally, a 12 air plenum is required between the walls and stacks of lumber. Consider the weight of the lumber that will be placed in the structure and fortify the building accordingly. Analysis of the chemical constituents of dry-kiln condensate and its For all kiln drying schedules, a heater should be used to sterilize the lumber and kill any insects that may be present. 0000006274 00000 n They are based on different air flow rates, etc. Insulate the floor with 2 rigid foam for convenience and durability. In the third column, write down the appropriate dry-bulb temperatures. Anyway, I included my log of a load I did in Nov '06 for everyone's amusement. The fact is, most of my stacks of lumber air dry to 15% moisture content before entering the kiln. This can create internal stress in the lumber that is released when sawing. The baffles direct airflow over and through the stack and prevent the top layers from drying too quickly. For all kiln drying schedules, a heater should be used to sterilize the lumber and kill any insects that may be present. When the operating conditions of this option are followed the material will meet the requirements of being kiln dried (KD) and heat treated . 0 \ (Note: This letter designation is related to the green MC of the species. The thinner the stock, the more critical sticker placement becomes. An anemometer confirms that your effort constructing baffles was worthwhile. 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.. I dont think the same could be said for an old reefer truck converted into a kiln (no matter how well it dries lumber). November 1, 2020. Basically, you don't want all of the air rushing out under the stack, so find a way to redirect it. I like these "starter blocks" to raise the lumber a few inches off the floor. In larger kilns, the heater may be needed in the latter part of the drying cycle. Use the gridded drawings provided on the PDF, Woodworking | Blog | Videos | Plans | How To. 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. 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. This lets the operator sort stacks by lumber species, so they will be easy to retrieve when the drying cycle is complete. Instead of using expensive electrically reversible fans designed for commercial kilns, I came up with a simple hardware solution. Official websites use .gov Another common sticker size is 1" x 2", and these work fine as well. In-service replacement of warped 2 by 4's as wall studs or truss members is costly. Maderas. To hang the baffles, simply attach hooks to the plywood frame. 73. 3.24 solar-dehumidification drying kiln Adjust the baffles or fan direction to achieve good airflow. A discussion of how to apply "safe drying rate" calibrations with a home-built dehumidifying kiln. Difficult-to-dry species might not exceed 60 C (140 F). After a short period of grumbling, they join me to lay down wood blocks for the first layer of lumber. Small, complete dehumidification dry kilns under 5,000 board-foot capacity are not available for sale. . To browse Academia.edu and the wider internet faster and more securely, please take a few seconds toupgrade your browser. Our approach was to build and operate a small dehumidification dry kiln. Abstract. Kiln Systems. Measure airflow over the stacks of lumber in various locations. For a kiln temperature of 140 F, sterilization takes three to five hours. In smaller kilns, the heat generated by the fans and DH motor is sufficient to maintain temperatures in excess of 100 degrees. For the sterilization phase, air temperature needs to be around 140 F, for three to five hours. With a well-designed dehumidification kiln, hardwood lumber can be dried for mere pennies per board foot. There might be a problem with that if the chamber overheats and has to be vented because some water will leave that way. The conversion method described in the Dry Kiln Operator's Manual is not really accurate, but it is safe. Windows and doors are also sealed, as well as any holes cut for electrical service. 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. A heavy-duty 1,500-watt space heater works fine. I know your kiln is absolutely tight and perfectly sealed, but it has to vent some or it would overheat. November 2017 - tech update - Dry Kilns - Forestnet Subtract the wet-bulb depression from the dry-bulb temperatures for each schedule step and enter the value in the fifth column. 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 . (A major source was Dry Kiln Schedules for Commercial Woods which is available from the Forest Products Society in Madison, WI.) Using a Kiln Schedule 6. 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 . I have constructed a kiln using these plans. Also, since heat rises, ceiling-mounted fans have the added benefit of circulating the warmest air over the lumber. The schedule designations use the popular U.S. Forest Products Laboratory designations. USDA, 1991) . I also wrapped the shed with Tyvek HomeWrap. Kiln drying is almost always essential for wood intended for interior uses. Detailed design and custom manufacture of dehumidification and chiller systems for food processing, lumber drying and industrial applications. txN.a!HQ)FmCw~{B1Aq_!+zN#+j Techniques and Procedures for The Quality Drying of Oak Lumber Dehumidification Kilns | Nyle Systems | Brewer, Maine Exterior sheathing and siding type also factors into the heat-holding ability of the structure. For sterilizing thicker lumber, additional time is required. Staggering the seams between the sheathing and siding layers helps avoid air infiltration. 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 cost associated with shed construction was similar to buying a prefabricated kit. After two days operating only the fans and DH, I take note of the temperature. 6 0 obj temperature. My kiln uses four ceiling-mounted fans, each rated for 1,600 CFM. With two-stack and three stack kilns, it is better to have reversible fans to alter the direction of airflow mid-cycle. Once all the lumber is stacked and stickered, place baffles over the lumber. For the sterilization phase, air temperature needs to be around 140 F, for three to five hours. 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. But kiln drying may also introduce internal stresses into the woodparticularly if an improper kiln schedule is used, . Be sure that all of the kiln equipment is working prop-erly before lumber is loaded into the kiln. After a short period of grumbling, they join me to lay down wood blocks for the first layer of lumber. If your lumber stack is built on starter blocks, you will need to limit airflow there as well. Always use adequate samples representing both the wettest and driest lumber in the dryer. Also, for that approach to work, the chamber needs to be air tight. This air space is absolutely critical for even airflow, so count on the extra floor space right from the design phase. Equalizing and Conditioning Many regions have increased the shed and outbuilding maximum allowable size without need for a permit. I've been drying hardwood lumber in this Sauno dehumidification kiln for 4 years with excellent results. 301 0 obj <>stream Nyle. Made in China, it exudes the classic style of Asian and Chinese cultures, featuring a unique shape that sets it apart from traditional jars. A lazy Susan with 180 detents mounts the fan box to the ceiling. Size and placement of the access door are critical as well. You won't ever have the fastest kiln in town, but it can still work. This gives me a secondary method of tracking the drying process, using both water volume and moisture content (MC) readings. This will allow the heater to cycle on and off automatically, according to the kiln operator's setting. 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 a professional DH kiln, the final climate for oak is 120F and <40>t over-dry it at that rate. Share sensitive information only on official, secure websites. . Dehumidifier Kiln Schedule | Dehumidifier Supply For international returns, please click here. This plan allows . Soon the DH won't show much water collected in the tray. 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. Thicker lumber like 5/4 or quartersawn lumber is naturally more stable. Remove samples from the stack, and cut an inch or two off one end. Take the electronics out of the kiln, and continue operating the heater and fans during this phase. Installing a window in a kiln may seem counterintuitive at first, because windows lose more heat than an insulated wall. This serves a dual purpose of supporting the rigid foam insulation as well as stiffening the floor framing. If the interior volume of a kiln becomes too large, basic heaters and home dehumidifiers may be inadequate to control the kiln environment. Farm Forestry timbers - Drying (Seasoning) Timber Any small building could work, as long as it has a minimum of 2 x 4 framing, and will seal out unwanted air. I prefer to empty the water tray manually and record the volume of water collected. The lumber was then measured for crook, bow, and twist. 0000006297 00000 n These figures hold true for lumber up to 2" thick. PDF An Overview of Drying Hardwood Lumber