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Q,kjifT33P[! A lower RH setting will call for the DH to run more often. 158 p. Dry kiln schedules for commercial woods : temperate and tropical. This returns some moisture to the very dry exterior of the lumber, while not affecting the core moisture level. Its a nice use of technology and adds a measure of safety as well.) The fact is, most of my stacks of lumber air dry to 15% moisture content before entering the kiln. hb```[@9p(T-3jO:g)@S
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Soon the DH wont show much water collected in the tray. 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. To condition the lumber, I introduce steam into the kiln for about two hours. 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. 9. Most species of hardwood lumber can be safely dried this way, once the moisture content is 20% to 25% or less. These figures hold true for lumber up to 2" thick. Our approach was to build and operate a small dehumidification dry kiln. 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. Many available kiln designs require a large, heavy door. End baffles are also a good idea to prevent airflow from bypassing the stack entirely. 0000000591 00000 n
Also check that air isnt escaping around the side baffles or under the stack of lumber. Also check that air isnt escaping around the side baffles or under the stack of lumber. 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. WOODWEB is a registered trademark of Woodweb.com. 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. If we revisit the example of a $1,300 gross savings from a load of 540 BF of white oak lumber, and we subtract the estimated cost of $62 to kiln dry the lumber, we arrive at a net savings of $1,238 less than retail. I decided on a dehumidification kiln after reading an article in Fine Woodworking (1991). The T-bars are made from 1/2" galvanized pipe and are attached to the rafters with threaded pipe flanges. For a small scale shed kiln, I recommend a maximum footprint of 200 square feet. (Note: This letter designation is related to the green MC of the species. Installing a window in a kiln may seem counterintuitive at first, because windows lose more heat than an insulated wall. I modified one of the Radio Shack combo units so it could measure the RH remotely as well as the temp. Each layer of lumber is separated from the next by a series of stickers or spacer sticks. The kiln climate is controlled by venting the hot air and replacing it with ambient air. Typical dehumidification kiln (FPL 1999 p. 12-10). 0 \ There are two ways to remove water from the DH unit, and they both work well. My shed kiln was stick-built from standard building material, and sized to take advantage of typical 4 x 8 sheet goods. Diy dehumidifier kiln time table. 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. Select 3/4" conduit brackets for hanging baffles on 1/2" galvanized pipe. 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 . Temperatures inside the kiln range from 120 to 190 degrees F, depending on the stage of . BE CAREFUL--The first temperature value must be repeated for every MC class (column #2) that is above 30% MC. Leave an air space between the rigid foam and subfloor for additional insulating properties. Thicker lumber like 5/4 or quartersawn lumber is naturally more stable. End baffles are also a good idea to prevent airflow from bypassing the stack entirely. In exchange for building the shed myself, I wound up with a shed of higher quality, with more features. Formulating a Kiln Schedule Dehumidification drying equipment is available, but an enclosure must be built to house the equipment and dry the lumber. The kiln humidity can be expressed as an EMC, relative humidity, or wet-bulb temperature. Contractors work on a tight schedule, and that may not allow much time for curing and drying concrete. Air speed of 350 feet per minute is appropriate for common hardwoods such as oak and maple. A shed kiln is an attractive alternative for a couple of reasons. Determine the correct designation, such as T3-D2 for 4/4 red oak. Once all the lumber is stacked and stickered, place baffles over the lumber. The store will not work correctly in the case when cookies are disabled. John Baines Reply to Dann Barry 1 year ago Any small building could work, as long as it has a minimum of 2 x 4 framing, and will seal out unwanted air. I have been reading & studying kiln schedules for years too. Then, write down the appropriate MC ranges (determined in #2 above) in the second column. Additionally, I have been underwhelmed by the performance of solar-operated fans. For a kiln temperature of 140 F, sterilization takes three to five hours. In this research, a drying restraint system was evaluated as a means of warp reduction in 8- and 16-foot-long SYP lumber. However, you may need more cycles depending on the species, moisture content, and size of the timber. Conventional kiln drying. Place a 16 board on the floor behind the stack, tilted to a 45 angle. A.gov website belongs to an official government They are normally mounted in the gable of household attics, and they are designed to be used in high temperature environments. Recently, either Wood, or American Woodworker showed how to build a small version of a solar kiln. Initially, I set the DH to 40% RH, because I dont want to remove moisture too quickly. For example, if you dry 7,500BF of fast drying Pine, you'd select the 8MBF chamber with the HT18 . Measure airflow over the stacks of lumber in various locations. Apply foil tape to the edges of the main baffles to help protect the Styrofoam. A small electric heater supplies auxiliary heat to maintain adequate kiln temperature. In contrast, a dehumidification kiln uses a sealed chamber, with only enough energy input to maintain the desired temperature. This Blue&White Ginger Jar is a stunning piece of porcelain and pottery, expertly handcrafted with natural variations in each piece. Dehumidification Kilns At the planer mill, warped 2 by 4's represent a significant loss in value. . Website Content Copyright 2023 Nyle Systems |. With each load I did not have the initial relative humidity rate. A 1.5-kW dehumidifier was installed in the solar dryer to determine the performance of a combined solar-dehumidification dryer. Wood Shrink/Swell estimator - A web-based program to estimate shrink/ swell in wood. ) or https:// means youve safely connected to the .gov website. The lumber was then measured for crook, bow, and twist. A free BASIC program to convert the designations into actual temperatures and humidities is available from the author. With advances in spray foam insulation, it may be possible to seal older, drafty structures as well. The common lumber name is used throughout. At the end of the cycle I have the opposite problem. 906 0 obj
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However, because wood from Commercial scale steam kilns consume large amounts of energy. Add up the amp draw on all the equipment you plan to use in the kiln, including a heater, dehumidifier, fans and steam generator. If the fans and dehumidifer generate enough heat to maintain a temperature of 100 to 120 F, then I wont use the auxiliary heater. Attic fans are a perfect way to provide airflow over the stacks of lumber. You can achieve top-quality results with incredible efficiency. Heat comes primarily from an integral dehumidification unit that also removes . Main thing is to not rush drying in first stages, as this will cause problems. Willie Sandry is a furniture maker and a lumber kiln operator in Camas, Washington. I hope that the sawyer coated the ends of the lumber with Anchor-Seal or oil-based paint when it was green. I made a simple frame from plywood strips and attached the insulation sheets to them with screws and fender washers. Go to the second number designation (the wet-bulb depression designation) and find the corresponding depressions in the table below. I have constructed a kiln using these plans. My baffles hang from T-bar assemblies mounted to the ceiling. This makes lightweight baffles that can be easily moved and repositioned. )f7haRoMRhib5Sd|-=RBkBBN r-hzf+1\IFgk;v]3_, KxL$9oL "Qw#"BFGfk}>cT2g yP K|7@N*v9!Wy9jB. op(y"X)Fz"q]fQC/ha>7=k_p}}^VXQmj e'2fyXQ{~23X^H1,d>Hq|^KQ*cN=yF%z. Check your local building codes for regionally specific requirements and electrical permits. (Sawing and Drying Forum) A kiln schedule is a set of temperatures and humidities that are used during kiln operation. I prefer to empty the water tray manually and record the volume of water collected. On the last load of lumber I purchased, I saved $2.50 per board foot compared to retail prices for kiln-dried lumber. In this system, moist air is not vented out of the kiln but is dehumidified, then recirculated . Changing the position of the doorway in various kiln setups helps provide the best access to the stacks of lumber. A household dehumidifier (DH) removes moisture from the kiln chamber. With two-stack and three stack kilns, it is better to have reversible fans to alter the direction of airflow mid-cycle. For all kiln drying schedules, a heater should be used to sterilize the lumber and kill any insects that may be present. For all kiln drying schedules, a heater should be used to sterilize the lumber and kill any insects that may be present. Without baffles, the top layers of lumber experience potato chipping with cupping, twisting or warping. Wood-Mizer dehumidification and solar wood kilns range from 300 to 35,000 board feet capacity for drying lumber. Any info or advice on using dehumidification equipment to dry out chainsaw milled lumber. Kiln drying is the process of drying wood in a controlled environment, where temperature, air circulation and humidity are monitored and stabilized. But kiln drying may also introduce internal stresses into the woodparticularly if an improper kiln schedule is used, . A higher humidity setting will run the unit sporadically to maintain that RH. Case hardening is a defect caused by the outer portion of a board drying quickly, while the inner portion dries more slowly. I use a Rockler steam generator, item #42826 (www.rockler.com). Also, for that approach to work, the chamber needs to be air tight. These kilns will typically hold several thousand board foot of lumber. I prefer to empty the water tray manually and record the volume of water collected. For a kiln temperature of 140 F, sterilization takes three to five hours. Go to the first number designation (the temperature designation) and find the corresponding temperatures in the table below. Difficult-to-dry species might not exceed 140 degrees F. Dehumidification kilns are very . (See the following sections for a discussion of how to develop a schedule from these designations.) Share. Created and Presented by: Henco Viljoen and Elijah McCarty with Nyle Dry Kilns. Another reason I like the idea of a shed kiln is the flexibility of future use. Taking moisture away at the rate the board will "safely" part with it . %PDF-1.6
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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. Our approach was to build and operate a small dehumidification dry kiln. A discussion of how to apply "safe drying rate" calibrations with a home-built dehumidifying kiln. Many regions have increased the shed and outbuilding maximum allowable size without need for a permit. %%EOF
These well-known dehumidification kiln packages have been among our bestselling products for the past 30 years. This fact sheet summarizes the basics of kiln drying wood, the most commonly used methods, drying schedules and some drying defects. 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. . My kiln schedule starts with running all fans and the dehumidifier for two days, measuring and removing water as it accumulates. 0000006297 00000 n
Bring your moisture meter to confirm. Standard kiln drying temperatures are low - around 120 degrees Fahrenheit or so, and drying times vary by wood size and moisture level. A lazy Susan with 180 detents mounts the fan box to the ceiling. This lets the operator sort stacks by lumber species, so they will be easy to retrieve when the drying cycle is complete. As you can recycle . A dehumidification kiln makes sense particularly when the lumber is air-dried first. 2. Dehumidification kilns from Nyle Systems in Brewer, Maine. After four days, I decrease the RH setting on the DH to 30% and continue to run the fans. endstream
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Should a Moulding Mill Bring Sawmill Operations In-House? 3, a simplified transverse section of a kiln chamber with an energy recovery and dehumidification system is shown. Select a heater with an adjustable thermostat and a tip-over shutoff. There might be a problem with that if the chamber overheats and has to be vented because some water will leave that way. The starter blocks should be as long as the stack is wide. The last step requires a short period of high humidity to relieve the drying stresses in the boards. For a kiln temperature of 140 F, sterilization takes three to five hours. Place a 1x6 board on the floor behind the stack, tilted to a 45 angle. My kiln schedule starts with running all fans and the dehumidifier for two days, measuring and removing water as it accumulates. 301 0 obj
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For a single-stack kiln I recommend a minimum shed size of 8 x 12. Schedules. 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 . /Subtype /Image
Align the stickers over the starter blocks on the first course. They are based on different air flow rates, etc. A small electric heater supplies auxiliary heat to maintain adequate kiln temperature. This slows the end-grain drying and limits the severity of end checking. Secure .gov websites use HTTPS The baffles do not need insulating properties, and plywood would work just as well. My four main baffles consist of sheets of 1" Styrofoam insulation. Madison, WI: U.S. Department of Agriculture, Forest Service, Forest Products Laboratory. 0000001186 00000 n
Anyway, I included my log of a load I did in Nov '06 for everyone's amusement. Its a nice use of technology and adds a measure of safety as well.) Remove samples from the stack, and cut an inch or two off one end. 7. Corrosion resistant epoxy coated aluminum cabinets and specially coated dehumidification coils for an extra long life. The DH is not needed at this time, as the lumber is already bone-dry. The kiln schedule information in the tables below has been assembled from many different sources, including drying texts and industrial contacts. It is a good idea to sterilize the lumber at the end of the kiln run. By setting the relative humidity (RH) on the dehumidifier, you can control how often it runs. HDE small kilns feature all-aluminum construction for a long, maintenance-free life span . Question Do not know just how the end point of moisture would compare. Omitting the sterilization phase can lead to costly losses from insect damage, so dont skip it. Place a sticker at each end, and every 16 along the stack for 4/4 stock. Hardwood kiln drying schedules typically keep the dry bulb temperature below 80 C (176 F). H6`2}s=n:l)CR>/"\ This helps keep the lumber straight during the drying cycle; in fact, improper placement of stickers can permanently deform lumber. Schedule for drying 4/4 and 5/4 upland red oak in a steam dry kiln. 5. The starter blocks should be as long as the stack is wide. /Name /ImagePart_0
- Model L300, L500, L1200-S Series - Medium Dehumidification Dry. The conversion method described in the Dry Kiln Operator's Manual is not really accurate, but it is safe. I either use some cedar 3" x 5", or 4" x 4" stock. Delete from my manuals. Kiln schedules are completely assembled and written out for easy use. For end baffles, I use 2-thick rigid foam insulation screwed to the main baffles. Know how to choose and apply the correct schedule for the lumber. /Length 7 0 R
Exterior sheathing and siding type also factors into the heat-holding ability of the structure. Total costs for the materials were $2,704 based on 2006 prices. Another great option is to convert an existing shed or outbuilding to a lumber kiln. I then manually rotate the fan boxes halfway through the drying cycle. The approach described in the article where you try to keep the water leaving at a steady rate is fine. So, with that lengthy introduction, here is my question. For sterilizing thicker lumber, additional time is required.