(See the following sections for a discussion of how to develop a schedule from these designations.) Heat comes primarily from an integral dehumidification unit that also removes . 0000000710 00000 n Take a moisture reading in the end grain with a pin-type moisture meter or remote probe.) I prefer to empty the water tray manually and record the volume of water collected. Recently, either Wood, or American Woodworker showed how to build a small version of a solar kiln. WOODWEB is a registered trademark of Woodweb.com. A higher humidity setting will run the unit sporadically to maintain that RH. 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). If MC readings still arent at the desired range, the heat may need to be increased for the remainder of the drying cycle. (Sawing and Drying Forum) The Bolivian wood products industry was surveyed to determine lumber drying capacity, technology and. Delete from my manuals. However, if you kiln dry hardwood lumber that has already been air dried, the process is much more forgiving. 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. Place some sample boards in the stack that will be easy to pull out for moisture testing later. Dehumidification dry kilns operate at lower drying temperatures (typically below 150F) than do conventional kilns, which results in longer drying schedules. Minus the drying equipment, a shed kiln is just an insulated storage space, with a host of possible uses. I usually see a large volume of water in the DH each night when I check the kiln. Electrical requirements for a DIY kiln are pretty straightforward, but hiring an electrician is still a good idea. 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 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 With a 130 F kiln temperature, sterilization will take 10 to 12 hours (Dry Kiln Operators Manual, 1991). . Commercial scale steam kilns consume large amounts of energy. A better choice might be a solar kiln, as you can dry wood from "wet" to 6-8 percent MC in 6-8 weeks. Place a sticker at each end, and every 16 along the stack for 4/4 stock. )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. Omitting the sterilization phase can lead to costly losses from insect damage, so dont skip it. << I am also curious why an initial temperature of 90F would have been selected. Abstract. Difficult-to-dry species might not exceed 140 degrees F. Dehumidification kilns are very . If your lumber stack is built on starter blocks, you will need to limit airflow there as well. This kicker board will help distribute the airflow more evenly through all layers of lumber. 4.4 drying schedule moisture content drying schedule . 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. 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. Formulating a Kiln Schedule Instead of using expensive electrically reversible fans designed for commercial kilns, I came up with a simple hardware solution. 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. After a short period of grumbling, they join me to lay down wood blocks for the first layer of lumber. My question focuses on the initial relative humidity featured in the Safe Drying Rate table. These well-known dehumidification kiln packages have been among our bestselling products for the past 30 years. /Height 2587 However, because wood from If you dry 9,500BF of slower drying Oak, youd use the 10MBF chamber with the HT8 Dehumidifier. Each layer of lumber is separated from the next by a series of "stickers" or spacer sticks. The kiln humidity can be expressed as an EMC, relative humidity, or wet-bulb temperature. Kiln Drying . Rocky Mountain . Additionally, a 12 air plenum is required between the walls and stacks of lumber. Leave an air space between the rigid foam and subfloor for additional insulating properties. Check out More On the Web for my complete calculations to figure savings. If you use a lot of lumber, and youre a decent hand at carpentry, a shed kiln will quickly pay for itself. A locked padlock Also check that air isnt escaping around the side baffles or under the stack of lumber. These kilns will typically hold several thousand board foot of lumber. The delicate blue and white color scheme c For all kiln drying schedules, a heater should be used to sterilize the lumber and kill any insects that may be present. H6`2}s=n:l)CR>/"\ I cannot stress the importance of baffles enough. The membrane was taped and lapped to the weather so if the tape ever fails, any rain that gets behind the siding would still be shed down and away by the HomeWrap. The stickers are uniform in size and usually 3/4" or 1" square. In-service replacement of warped 2 by 4's as wall studs or truss members is costly. The thinner the stock, the more critical sticker placement becomes. For a kiln temperature of 140 F, sterilization takes three to five hours. The second most common type of drying is called dehumidification drying. Extruded polystyrene foam (blue or pink rigid foam) in this thickness has an R value of 10. To condition the lumber, I introduce steam into the kiln for about two hours. (I have found that remotely monitoring the temperature and humidity with a WiFi sensor can be very helpful. Any info or advice on using dehumidification equipment to dry out chainsaw milled lumber. I modified one of the Radio Shack combo units so it could measure the RH remotely as well as the temp. The kiln climate is controlled by venting the hot air and replacing it with ambient air. The column on the right I added part way through is the kiln's internal RH. There may be more depression values than required; ignore the extra depression values in this table. A maximum 45 F depression often produces better lumber. Another great option is to convert an existing shed or outbuilding to a lumber kiln. If it isn't overheating, it is leaking. Determine the equalization settings and conditioning settings, as required. 0 These figures hold true for lumber up to 2 thick. Lock 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 . This problem is magnified if the lumber is thin or flatsawn. Dehumidification: This kiln-drying process requires the use of a heat pump system to remove water from the wood. Sears Canada 70 Pint Dehumidifier. 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. 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. I can show you the kiln schedules and data. Website Content Copyright 2023 Nyle Systems |. Although I can maintain the 90 degree temperature, I could not start at the recommended humidity level unless I added humidity. Wood Drying/ Seasoning. Another common sticker size is 1 x 2, and these work fine as well. _0e`bd\ p@ Anyway, I included my log of a load I did in Nov '06 for everyone's amusement. /Subtype /Image 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. Basically, you dont want all of the air rushing out under the stack, so find a way to redirect it. I dont think the same could be said for an old reefer truck converted into a kiln (no matter how well it dries lumber). 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. You won't ever have the fastest kiln in town, but it can still work. Once the core readings are 6% to 8% on a fresh cut, the lumber is dry and ready for sterilization. Soon the DH wont show much water collected in the tray. With a 130 F kiln temperature, sterilization will take 10 to 12 hours ( Dry Kiln Operators Manual, 1991 ). There are many types of kilns, but the most common are dehumidification kilns and conventional kilns. Evaluation of kiln-drying schedules for wild cherry wood (Cerasus avium), Model to assess energy consumption in industrial lumber kilns, Mathematical modelling and experimental investigation of dehumidifier drying of radiata pine timber, A survey of Bolivian lumber drying operations, Warp reduction of SYP lumber by restrained drying, Western Juniper Drying Project Summaries, 1993-96, Vacuum contact drying kinetics of Jack pine wood and its influence on mechanical properties: industrial applications, Kiln drying behavior of lumber from ten fast-growth plantation species in Costa Rica, Effect of fire-retardant treatment and redrying on the mechanical properties of Douglas-fir and aspen plywood, Properties of Douglas-Fir and Aspen Plywood, A numerical study on the influence of the bond-line diffusivity on moisture-related stresses and deformations of three-layered spruce cross-laminates, Error in Estimates of the Moisture Content of White Oak Kiln Sample Boards, Green Kerfing Treatment for Improving Softwood Lumber Drying: A Review, A comparison of kiln-drying schedules and quality outcomes for 4/4-thickness black cherry lumber sawn from small-diameter logs, A comparison of kiln-drying schedules and quality outcomes in 4/4-thickness black cherry lumber sawn from small-diameter logs, Data bank for short-length red oak lumber, Hardwood lumber widths and grades used by the furniture and cabinet industries: Results of a 14-mill survey, Lumber and veneer recovery from intensively managed young-growth Douglas-fir, WOOD-FRAME HOUSE CONSTRUCTION U.S. DEPARTMENT OF AGRICULTURE FOREST SERVICBAGRICULTURE HANDBOOK NO. 1. Total costs for the materials were $2,704 based on 2006 prices. 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 Y}-m+'@DQ4\h8GP]y@ yL. If severe enough, the lumber can develop honeycomb cracks throughout. ) or https:// means youve safely connected to the .gov website. Dr. Gene Wengert provides schedules for kiln drying hardwood lumber. In addition, wood can be dried by special methods that include solar drying (use of greenhouse-type dryers or those equipped with solar collectors . 282 0 obj <> endobj 0000004213 00000 n 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.) 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 capacities are 4,000 board feet in a kiln . Different species should not be loaded simultaneously into the kiln due to often differing kiln schedules. 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. 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. This returns some moisture to the very dry exterior of the lumber, while not affecting the core moisture level. The air flow rate through your stacks should be about 350FPM. in the kiln to dry specific wood products at a satisfactory rate without causing objectionable drying defects. The KD150 Dehumidification Kiln Kit is a compact, entry-level dehumidification kiln for drying lumber between 300 and 1000 board feet. If your lumber stack is built on starter blocks, you will need to limit airflow there as well. After four days, I decrease the RH setting on the DH to 30% and continue to run the fans. 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. 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. This makes lightweight baffles that can be easily moved and repositioned. HWn8gXA N,[mKJr2"Ec9,t 301 0 obj <>stream Question JavaScript seems to be disabled in your browser. I hope that the sawyer coated the ends of the lumber with Anchor-Seal or oil-based paint when it was green. . After two days operating only the fans and DH, I take note of the temperature. In the third column, write down the appropriate dry-bulb temperatures. Unfortunately, little information is available regarding lumber drying technology and practices used, which is essential for the formulation of improvement strategies. Any small building could work, as long as it has a minimum of 2 x 4 framing, and will seal out unwanted air. I find that unplugging the DH is helpful during the sterilization phase so I can add a second heater, without overwhelming my electrical circuit. Rep. FPL-GTR-57. Remote operation and networking is optional. 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. Vacuum Kiln Drying. The cost associated with shed construction was similar to buying a prefabricated kit. Measure airflow over the stacks of lumber in various locations. For example, if you dry 7,500BF of fast drying Pine, you'd select the 8MBF chamber with the HT18 . Detailed design and custom manufacture of dehumidification and chiller systems for food processing, lumber drying and industrial applications. For example, if you dry 7,500BF of fast drying Pine, youd select the 8MBF chamber with the HT18 Dehumidifier. Schedules for several thicknesses and specialty products (e.g. . HT systems use 40-60% less energy than gas-fired or steam dry kilns. Size and placement of the access door are critical as well. 0000003109 00000 n Case hardening is a defect caused by the outer portion of a board drying quickly, while the inner portion dries more slowly. 0 \ Always use adequate samples representing both the wettest and driest lumber in the dryer. When the operating conditions of this option are followed the material will meet the requirements of being kiln dried (KD) and heat treated . To hang the baffles, simply attach hooks to the plywood frame. 6. I made a simple frame from plywood strips and attached the insulation sheets to them with screws and fender washers. Air speed of 350 feet per minute is appropriate for common hardwoods such as oak and maple. The DH is not needed at this time, as the lumber is already bone-dry. This problem is magnified if the lumber is thin or flatsawn. I then manually rotate the fan boxes halfway through the drying cycle. Sorry, preview is currently unavailable. A pre-hung steel exterior door is ideal in this situation, because it offers weatherstripping and is fully insulated. This can create internal stress in the lumber that is released when sawing. Dehumidification drying equipment is available, but an enclosure must be built to house the equipment and dry the lumber. Dehumidification Kiln. Sticker spacing can be increased to 24 apart for 5/4 or thicker hardwood. The starter blocks should be as long as the stack is wide. The four charges of lumber ranged from 600 to 700 board feet (bf), and a woodworker with no dry-kiln experience operated the kiln. 8. (I have found that remotely monitoring the temperature and humidity with a WiFi sensor can be very helpful. For sterilizing thicker lumber, additional time is required. endstream endobj startxref Drying small amounts of lumber using a dehumidification kiln is a suitable option for woodworkers even with limited knowledge of kilns. They are normally mounted in the gable of household attics, and they are designed to be used in high temperature environments. %3.3 It should be double-pane, well-insulated with low emissivity (low-E). Dehumidification Opportunities for Dehumidification Drying Of Hardwood Lumber Dimension Kiln Drying Hardwood Dimension Parts Discoloration Preventing Discolorations in Hardwood and Softwood Logs . Oregon-based HDE Dry Kilns has launched a new line of small kilns ranging from 2,000 to 12,000 board feet. The T-bars are made from 1/2 galvanized pipe and are attached to the rafters with threaded pipe flanges. Place a 1x6 board on the floor behind the stack, tilted to a 45 angle. Most species of hardwood lumber can be safely dried this way, once the moisture content is 20% to 25% or less. A dehumidification kiln continuously recycles the heat throughout the chamber, rather than . Kiln drying is usually preceded by air drying to bring the moisture content of the wood down below 30%. %PDF-1.4 % Only the fans need electricity. Looking at the cost-benefit analysis of a shed kiln can be enlightening. 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 like these starter blocks to raise the lumber a few inches off the floor. The baffles do not need insulating properties, and plywood would work just as well. The kiln schedule information in the tables below has been assembled from many different sources, including drying texts and industrial contacts. A dehumidification kiln makes sense particularly when the lumber is air-dried first. In a professional DH kiln, the final climate for oak is 120F and <40>t over-dry it at that rate. In Fig. A variety of wood drying kiln technologies exist today: conventional, dehumidification, solar, vacuum and radio frequency. An official website of the United States government. After seven to 10 days, I reverse the fan direction to make sure all stacks of lumber dry evenly.