Willie Sandry is a furniture maker and a lumber kiln operator in Camas, Washington. Excel Program for Modeling Lumber Dry Kiln Operations - a model for lumber dry kiln operation. This kicker board will help distribute the airflow more evenly through all layers of lumber. Phytosanitary heat treatments of Ceratocystis lukuohia and Ceratocystis huliohia-colonized Metrosideros polymorpha wood were evaluated using kilns. Schedules Dry Kiln Schedules for Commercial Woods The first thing to consider when designing a shed kiln is size. 0000004213 00000 n
If MC readings still arent at the desired range, the heat may need to be increased for the remainder of the drying cycle. Rocky Mountain . The KD150 Dehumidification Kiln Kit is a compact, entry-level dehumidification kiln for drying lumber between 300 and 1000 board feet. Check your local building codes for regionally specific requirements and electrical permits.
The last thing to do before starting the kiln is to close the gable vent with an insulated cover. 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.). 301 0 obj
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the hardwood kiln schedule is the equalization of the moisture content of all boards at 6-8%. Items shipped directly from the manufacturer cannot be returned in store. 2. My kiln schedule starts with running all fans and the dehumidifier for two days, measuring and removing water as it accumulates. This plan allows . Corners where walls meet should be sealed with expanding foam sealant. Formulating a Kiln Schedule Drying lumber too quickly can lead to deep end checking, warping and case hardening. For the best experience on our site, be sure to turn on Javascript in your browser. If required, look-up and write down the RH (sixth column) and EMC (seventh column) for each schedule step. /Width 1628
At the end of the cycle I have the opposite problem. 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. I prefer to empty the water tray manually and record the volume of water collected. Equalizing and Conditioning There are two ways to remove water from the DH unit, and they both work well. hb```[@9p(T-3jO:g)@S
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The velocity through the load is assumed to be between 275 and . To hang the baffles, simply attach hooks to the plywood frame. This shed will be essentially unheated for much of the year and very hot during the kiln-drying cycles. The DH is not needed at this time, as the lumber is already bone-dry. The kiln configuration and a drying schedule can be input and the code in the Excel file will simulate . 0000006274 00000 n
A lock ( I recommend a 2 x 3 sliding window with bug screen. 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 like these starter blocks to raise the lumber a few inches off the floor. The DH is not needed at this time, as the lumber is already bone-dry. Place the sample board in the lumber stack in a location where it will dry at the same rate as the rest of the lumber in the dryer (see Figure C). Using a Kiln Schedule This lets the operator sort stacks by lumber species, so they will be easy to retrieve when the drying cycle is complete. (Note: This letter designation is related to the green MC of the species. building the dehumidification dry kiln. These figures hold true for lumber up to 2" thick. Omitting the sterilization phase can lead to costly losses from insect damage, so dont skip it. Both restrained and control boards were dried to approximately 9 percent moisture content, representative of final in-service condi- tions. Wood drying (also seasoning lumber or wood seasoning) reduces the moisture content of wood before its use. 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. Basically, you dont want all of the air rushing out under the stack, so find a way to redirect it. 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. However, the natural light and ventilation offered by a small window outweighs any disadvantages. They are normally mounted in the gable of household attics, and they are designed to be used in high temperature environments. A locked padlock Our approach was to build and operate a small dehumidification dry kiln. Determine the equalization settings and conditioning settings, as required. Heres a classic project that both steps up and provides overflow seating. These well-known dehumidification kiln packages have been among our bestselling products for the past 30 years. Insulate the floor with 2 rigid foam for convenience and durability. This procedure is discussed in a following section. The four charges of lumber ranged from 600 to 700 board feet (bf), and a woodworker with no dry-kiln experience operated the kiln. Anyway, I included my log of a load I did in Nov '06 for everyone's amusement. /ColorSpace /DeviceGray
On the last load of lumber I purchased, I saved $2.50 per board foot compared to retail prices for kiln-dried lumber. If the fans and dehumidifer generate enough heat to maintain a temperature of 100 to 120 F, then I won't use the auxiliary heater. noun: kiln; plural noun: kilns. Additionally, I have been underwhelmed by the performance of solar-operated fans. This will allow the DH to drain automatically without you needing to enter the kiln. Dehumidification Kiln Drying. The kiln humidity can be expressed as an EMC, relative humidity, or wet-bulb temperature. 0000000710 00000 n
It is a meaningless exercise to try to convert those schedules for the kiln you built. After seven to 10 days, I reverse the fan direction to make sure all stacks of lumber dry evenly. In this research, a drying restraint system was evaluated as a means of warp reduction in 8- and 16-foot-long SYP lumber. If the temperature is below this range, I start the heater and adjust the thermostat accordingly. The schedules can also be formulated manually as follows. 0000006297 00000 n
Unlike general shop space, bigger is not always better for kiln design. Drying lumber too quickly can lead to deep end checking, warping and case hardening. 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. The kiln humidity can be expressed as an EMC, relative humidity, or wet-bulb temperature. For sterilizing thicker lumber, additional time is required. In this system, moist air is not vented out of the kiln but is dehumidified, then recirculated . Rep. FPL-GTR-57. If severe enough, the lumber can develop honeycomb cracks throughout. In smaller kilns, the heat generated by the fans and DH motor is sufficient to maintain temperatures in excess of 100 degrees. 0000003109 00000 n
The remaining width allows for a 36-wide door and space for your drying equipment. Temps are in Celsius (20C = 70F, 40C = 105F). If your lumber stack is built on starter blocks, you will need to limit airflow there as well. During the conditioning process, the only equipment operating are the fans, heater and the steam generator no dehumidifier. My baffles hang from T-bar assemblies mounted to the ceiling. The cost associated with shed construction was similar to buying a prefabricated kit. 3.24 solar-dehumidification drying kiln This will allow the heater to cycle on and off automatically, according to the kiln operator's setting. My question focuses on the initial relative humidity featured in the Safe Drying Rate table. 0000000591 00000 n
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$ &UD\q@u I am removing water about 50% below the SDR. As a result, the kiln schedules were too severe. Perhaps the best part: you wont need to calculate your lumber needs down to the board foot. Dont even think of powering your kiln with an extension cord. Construction of a kiln chamber is very similar to building a small house. Although dehumidification kilns are slower than conventional kilns for drying, the lower drying temperature has the reported advantage of less degrade and less shrinkage. in the kiln to dry specific wood products at a satisfactory rate without causing objectionable drying defects. Leave an air space between the rigid foam and subfloor for additional insulating properties. My aim was to develop a small dehumidification kiln for better control of the three key components of lumber drying: temperature, airflow and humidity. 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. %PDF-1.4
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If the temperature is below this range, I start the heater and adjust the thermostat accordingly. Dehumidification drying equipment is available, but an enclosure must be built to house the equipment and dry the lumber. However, you may need more cycles depending on the species, moisture content, and size of the timber. 73. Another common sticker size is 1" x 2", and these work fine as well. Take the electronics out of the kiln, and continue operating the heater and fans during this phase. This makes lightweight baffles that can be easily moved and repositioned. For these reasons, I feel it is best to let the shed breathe, and forgo a plastic vapor barrier. The following tables show some examples of oak schedules for steam dry kilns and dehumidification dryers. This can create internal stress in the lumber that is released when sawing. The second most common type of drying is called dehumidification drying. Dehumidification kiln schedules 145 Sterilizing, equalizing, and conditioning treatments 145 Sterilizing treatments 145 Mold 145 Fungal stain and decay 146 . A small electric heater supplies auxiliary heat to maintain adequate kiln temperature. Equalizing and conditioning are required for almost all hardwood lumber. This allows for a more gentle kiln schedule to fully dry the timber. I usually see a large volume of water in the DH each night when I check the kiln. Our capacities are 4,000 board feet in a kiln . If for any reason you are not satisfied with the merchandise you ordered, just return it within 90 days to receive a refund in the manner of original payment for merchandise only. Our approach was to build and operate a small dehumidification dry kiln. Apply foil tape to the edges of the main baffles to help protect the Styrofoam. 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 A household dehumidifier (DH) removes moisture from the kiln chamber. Also, since heat rises, ceiling-mounted fans have the added benefit of circulating the warmest air over the lumber. Take a moisture reading in the end grain with a pin-type moisture meter or remote probe. My kiln uses four ceiling-mounted fans, each rated for 1,600 CFM. A shed kiln has minimal venting (usually one or two gable vents) and sealed soffits. Enter the email address you signed up with and we'll email you a reset link. Dr. Gene Wengert provides schedules for kiln drying hardwood lumber. Recently, either Wood, or American Woodworker showed how to build a small version of a solar kiln. Low Temperature Kiln Drying Systems (120F) 300BF - 4000BF Capacity . For a kiln temperature of 140 F, sterilization takes three to five hours. An official website of the United States government. Changing the position of the doorway in various kiln setups helps provide the best access to the stacks of lumber. Share sensitive information only on official, secure websites. A shed kiln is an attractive alternative for a couple of reasons. Featuring lower cost drying at speeds equal to gas & steam, these kilns are continuously exceeding industry standards and changing the game. On this order alone, I saved over $1,300 by drying the lumber myself. 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. 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 maximum 45 F depression often produces better lumber. Warp in dimension lumber is a significant cause for loss in grade and value. Do not know just how the end point of moisture would compare. Question 3. This report contains suggested dry kiln schedules for over 500 commercial woods, both temperate and tropical. Basically the idea seems to be to maintain a constant temperature, and . For example, if you dry 7,500BF of fast drying Pine, youd select the 8MBF chamber with the HT18 Dehumidifier. In this paper, the effective schedules were further investigated for longer culm parts treated with boron. Without baffles, the top layers of lumber experience potato chipping with cupping, twisting or warping. . If the interior volume of a kiln becomes too large, basic heaters and home dehumidifiers may be inadequate to control the kiln environment. Contractors work on a tight schedule, and that may not allow much time for curing and drying concrete. A 1.5-kW dehumidifier was installed in the solar dryer to determine the performance of a combined solar-dehumidification dryer. Particularly, important investment has taken place in lumber drying capacity. The delicate blue and white color scheme c Main thing is to not rush drying in first stages, as this will cause problems. Nyle. . 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. When properly loaded, this kiln can dry approximately 600 board feet of 4/4" lumber. Kiln drying normally involves temperatures in the range of 40-75 C (about 100-170 F). Difficult-to-dry species might not exceed 60 C (140 F). You can achieve top-quality results with incredible efficiency. Dehumidification Kiln. temperature. 1. 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 . Its a nice use of technology and adds a measure of safety as well.) Chinese, Korean or Japanese kilns have an arch roof. MC values in the kiln schedules are based on the wettest half of the kiln samples. /Length 7 0 R
By. Dehumidification Opportunities for Dehumidification Drying Of Hardwood Lumber Dimension Kiln Drying Hardwood Dimension Parts Discoloration Preventing Discolorations in Hardwood and Softwood Logs . 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 major source was Dry Kiln Schedules for Commercial Woods which is available from the Forest Products Society in Madison, WI.) The approach described in the article where you try to keep the water leaving at a steady rate is fine. Align the stickers over the starter blocks on the first course.