There is not a single woodworking enterprise that can do without the wood drying procedure. To prevent the occurrence of various defects, it is customary to use special technology drying wood in a drying chamber. If you want to produce wood products yourself, you will also need a drying chamber for drying wood. Today we will talk about how to do it correctly.
The need to dry wood
How to dry a board efficiently and quickly? This question has interested every carpenter since ancient times. People have long been engaged in storing wood for many years in order to have time to dry it evenly. The grandfather prepared wood for his grandson, using the very material that his grandfather left him.
The importance of properly dried wood is colossal! For example, if wooden furniture, which is in the room, is made of too wet wood that has just been cut down, then it will dry out over time, because wood can dry out and decrease in size, which means it will deteriorate!
If the door to the house is made of excessively dry wood, it will swell over time and will not be able to close! If the door panel is assembled from blanks that are unevenly dried in volume, then it may burst or warp! Therefore, it is recommended to dry all wood blanks. In addition, drying protects the material from damage by wood-destroying fungi, prevents the size and shape of wood, and improves the physical and mechanical properties of wood.
Drying wood is a lengthy, complex and expensive procedure. Tree by traditional technologies heated with superheated steam or hot air. Dried wood can be transported and stored longer. In addition, during operation it does not deform. The boards are dried in steam chambers, where the possibility of internal damage is excluded.
Wood moisture concept
To fully understand the essence of the drying process, it’s worth diving a little into the theory. The procedure for removing moisture from wood is not entirely simple, because there are two types of moisture in the material itself. Wood consists of elongated plant cells. Moisture can be found in the cell walls and in their cavities, filling the microcapillary system. The moisture that is present in the spaces between cells and in their cavities is called free intercellular, and moisture in the cell walls is called bound intracellular.
The content of bound moisture in wood is limited. The state when the cell walls are characterized by maximum humidity when in contact with liquid moisture is called their saturation limit. It is generally accepted that the moisture content of the saturation limit does not depend on the rock and is on average 30%. If the wood's humidity is above 30%, then it contains free intercellular moisture. The wood of a freshly cut or growing tree has a moisture content above the saturation limit, that is, it is raw.
Depending on the purpose of wood blanks, wood is usually dried in different ways. The wood is dried to a moisture content of 6 - 8%, when the material is needed for mechanical processing and assembly of products for high-precision critical connections that affect performance (the production of skis, parquet or musical instruments).
Transport humidity is 18 - 22%. It is with this water content that lumber is suitable for transportation over long distances in warm seasons. Wood dried to such a moisture content is used mainly in standard house construction, in the production of ordinary containers and when there is no need for interchangeability during assembly.
Carpentry dampness is divided into several subspecies. Molded products ( terrace board, sheathing, floor boards, casing) must have a humidity of 15 ± 2%. Wood products (windows, doors, stairs and interior elements) made from solid or laminated wood can withstand humidity fluctuations from 8 to 15%.
Furniture humidity, depending on the level of the product and the use of solid or laminated wood, is 8 ± 2%, because it is at this humidity that the wood exhibits the most optimal characteristics for processing, gluing and subsequent use. But it is usually customary to reduce the humidity to 7-10%, performing partial sterilization of the wood and taking into account the uniformity of humidity throughout the tree, maintaining the mechanical properties of the material, and the absence of surface and internal cracks.
Wood drying modes
Depending on the requirements for the quality of wood, lumber can be dried in different modes, which differ in temperature level. In a mini drying chamber for wood, during the drying process, the air temperature gradually increases in stages and the relative humidity of the agent decreases. Drying modes are selected taking into account the thickness of the lumber, the type of wood, the final moisture content, the quality category of the wood being dried and the design of the chamber.
There are low- and high-temperature process modes. The first modes involve the use of moist air as a drying agent, the temperature of which in the initial stage is less than 100 degrees. There are three categories of these modes:
- The soft mode is capable of ensuring defect-free drying of the material while maintaining the natural physical and mechanical properties of the wood, including color and strength, which is important for drying wood to the transport moisture content of export lumber.
- The normal mode guarantees defect-free drying of wood with almost complete preservation of the strength of the material with minor color changes, which is suitable for drying lumber to its final moisture content.
- The forced mode maintains strength for static bending, compression and tension, but there may be a slight decrease in splitting or spalling strength with darkening of the wood, which is intended for drying wood to operational humidity.
For low-temperature modes, a three-stage change in the parameters of the drying agent is assumed, and from each stage to the next one the transition can be made only after the material reaches a certain level of humidity, which is provided for by the mode.
High-temperature modes provide for a two-stage change in the parameters of the drying agent, and you can move from the first stage to the second after the wood reaches a transitional moisture content of 20%. The high temperature regime is determined depending on the thickness and type of lumber. High temperature conditions can be used to dry wood, which is not used for manufacturing. load-bearing elements buildings and structures in which wood darkening and strength reduction are allowed.
Drying chamber concept
Chamber drying is the main method of drying wood. Drying chambers are required to dry softwood and hardwood to different quality categories. One of the most popular and economical methods of artificial dehydration of lumber is drying, when bound and free moisture is removed from the tree by applying heat to the wet wood with hot air and carrying away the evaporated excess moisture humidified and partially cooled air.
Drying chamber is completely ready installation, which is equipped with all the equipment necessary for drying wood. According to their design, wood drying chambers are divided into prefabricated metal and made of building materials. The latter are constructed directly in workshops or as separate buildings from materials that are widely used in industry. The chamber can be made entirely of monolithic reinforced concrete. Its walls can be made of solid red brick, and the ceiling can be made of monolithic reinforced concrete.
If several dryers are used, they are often combined into a single block, constructing a common control corridor where the heating distribution and system are located automatic control all cameras. Depending on the volume of wood loaded into the chamber, there may be horizontal or vertical transverse air circulation.
Loading of lumber into the chamber can be carried out in the following ways: on trolleys in the form of stacks along a rail track, like packages with a forklift. Heat transfer to wood can be carried out: by air, combustion products or superheated steam; radiant heat that comes from special emitters; solid body, if you organize contact with a heated surface; current that passes through wet wood; high frequency electromagnetic field, which penetrates wet wood.
Equipment for a wood drying chamber is divided into basic and additional. The main ones include the fan system, heating system, supply and exhaust ventilation and humidification, additional components include an insulated door and psychrometric unit, stacking trolleys, and a fan drive electric motor.
The process of controlling wood drying in a chamber can be automated. Automation is capable of maintaining the humidity and temperature of the environment in the dryer at a given level. The temperature is regulated by supplying coolant to the heaters or by switching on and off electric heater, and humidity - through the use of supply and exhaust ventilation and a humidification system.
The wood drying control system may have the ability to remote control humidity and temperature in the chamber. When drying lumber in a drying chamber, it becomes necessary to control the moisture content of the wood, for which a remote moisture meter is used, which allows you to check the moisture content of the wood at several points without entering the chamber. In the absence of external heat sources, the dryer can use autonomous heating modules and use gas, coal, wood waste, electricity and diesel fuel.
Types of drying chambers
In real life, it is common to use the following types of drying chambers. The necessary energy in convective drying chambers is transported into the material using the air cycle, and heat transfer to the wood occurs through convection. There are two types of convection chambers - tunnel and chamber.
Tunnel convection dryers are deep chambers where stacks of stacks are pushed from the wet end to the drier end. These chambers must be filled at one end and emptied at the other. Pushing the stacks (the process of filling the chambers and emptying them) is done one stack at a time with an interval of 4 - 12 hours. These chambers are designed for large sawmills and allow exclusively transport drying of wood.
Chamber convection drying chambers are shorter than tunnel and vacuum drying chambers for wood; during operation, the same parameters are maintained throughout the chamber. When the blowing depth is more than 2 meters, the technique of reversing the direction of ventilation is used to equalize the drying conditions for the wood. The emptying and filling of the chamber occurs on one side if it has one door. Other loading systems are also known that are similar to the procedure for loading tunnel chambers. Any lumber can be dried to any final moisture content, which is why 90% of wood in Europe and Russia is dried in chamber dryers.
The condensation drying chamber differs from the previous ones in that the humidity that arises in the air condenses on special coolers and water comes out of the drying process. The efficiency of such a process is large, but the cycle is long, because the devices do not operate at high temperatures, and the total heat losses are also significant. The condensation chamber is primarily suitable for drying small volumes of wood, or for drying dense wood species - oak, beech or ash. The big advantage of such chambers is that a boiler room is not needed, the price of a wood drying chamber and the cost of drying are lower.
Drying kilns are also classified according to the method of circulation and the nature of the drying agent used, the type of enclosure and the principle of operation. Batch drying chambers are characterized by the fact that they can be fully loaded to simultaneously dry all the material, and the wood drying mode changes over time, currently remaining the same for the entire chamber.
According to the method of circulation, there are chambers with incentive and natural circulation. Dryers with natural circulation are outdated, low-performance, the drying mode in them is almost uncontrollable, and the uniformity of wood drying is unsatisfactory. For modern construction such devices are not recommended, and existing ones must be modernized. Depending on the nature of the drying agent, the chambers are divided into gas, air and high-temperature chambers that operate in a superheated steam environment.
Wood drying procedure
Before drying according to the selected mode, the wood is heated with steam, which is supplied through humidifying pipes, with fans running, heating devices turned on and closed. exhaust ducts. First you need to calculate the drying chamber for wood. The temperature of the agent at the beginning of heating the wood should be 5 degrees higher than the first stage of the regime, but not more than 100 degrees Celsius. The level of saturation of the environment should be 0.98 - 1 for material with an initial humidity of more than 25%, and 0.9 - 0.92 for wood with a humidity of less than 25%.
The duration of the initial warm-up depends on the type of wood and is for coniferous species(pine, spruce, fir and cedar) 1 - 1.5 hours for each centimeter of thickness. The duration of heating of soft deciduous trees (aspen, birch, linden, poplar and alder) increases by 25%, and for hard deciduous species (maple, oak, ash, hornbeam, beech) - by 50% compared to the duration of heating of coniferous species.
After preheating, it is customary to bring the parameters of the drying agent to the first stage of the regime. Then you can start drying the lumber, subject to established mode. Humidity and temperature are regulated by valves on the steam lines and gates of the sugar-exhaust channels.
During the operation of an infrared drying chamber for wood, residual stresses arise in the wood, which can be eliminated by intermediate and final moisture-heat treatment in an environment of increased temperature and humidity. It is customary to subject lumber to processing, which is dried to operational humidity and subject to machining further.
Intermediate moisture-heat treatment is carried out during the transition from the second stage to the third or from the first to the second at high temperature conditions. Coniferous species with a thickness of 60 millimeters or more and deciduous species with a thickness of 30 millimeters or more are subjected to moisture and heat treatment. The temperature of the environment during the heat and moisture treatment process should be 8 degrees higher than the temperature of the second stage, but not higher than 100 degrees, with a saturation level of 0.95 - 0.97.
When the wood reaches its final average moisture content, final moisture-heat treatment can be carried out. In this process, the temperature of the medium is maintained 8 degrees above the last stage, but not higher than 100 degrees. At the end of the final moisture-heat treatment, the wood that has undergone drying must be kept in the chambers for 2 - 3 hours at the parameters provided for in the last stage of the regime. Then the drying chamber is stopped.
Making a drying chamber
If you decide to make wood products yourself, then you simply need a wood drying chamber. However, when constructing a dryer, comply with all required standards. You will need a chamber, a fan, insulation and a heating device.
Build a drying room or select a separate room, one wall and ceiling of which will be made of concrete, and the other walls will be made of wood, which need to be insulated. To do this, it is customary to create several layers: the first of them is polystyrene foam, the second is wooden boards, which are usually wrapped in foil in advance.
After this, you should install a heating element, which can be made in the form of batteries. Water must be supplied to the batteries from the stove, in which it will be heated to 60-95 degrees Celsius. It is advisable to continuously circulate water using water pumps in the heating element. Also, a fan should be placed in a homemade wood drying chamber, which helps distribute warm air throughout the room.
Consider how the wood will be loaded into the drying chamber. One loading option could be a rail cart. To regulate the humidity and temperature in the drying chamber, you need to use work area corresponding thermometers - wet and dry. Provide shelves inside the dryer to increase work space.
During the drying process of lumber, sudden changes in temperature in the working room are not allowed, otherwise this will cause the wood to warp or cracks to appear in it. When constructing a drying chamber, it is extremely important to observe fire safety requirements. Therefore, be sure to install fire extinguishers in the immediate vicinity of the dryer.
And finally, remember that instead of heating element At home, you can use a two-burner electric stove. You can insulate the walls of the drying chamber with your own hands using wood shavings. Instead of foil in the chamber, you can use penofol, which can provide good reflection of heat from the surface. In such a dryer, the wood is pre-dried 1-2 weeks in advance.
At the very beginning of the process, the air has quite high humidity and low temperature. The higher the initial moisture content of the tree, the more moisture there should be in the air entering the chamber. This is necessary in order to prevent cracking of the material. As the rock dries, the air temperature is gradually increased, while the moisture content in it, on the contrary, is reduced.
There is a strict relationship between air humidity and moisture content in the material. It can be determined using a special device - a psychrometer, which is used to determine the humidity and temperature of the air in drying chambers. The latter are called sushila. Exist various methods drying wood.
The factory method involves the use of special drying chambers. These are periodic steam-air dryers with reverse circulation. The resulting material, unloaded from there, is kept in the production workshop for two to three days. At this time, the material is normalized, that is, it is released from surface and internal stresses acquired during the drying process.
There are also drying chambers wood material. In such periodic devices, a special smokeless gas is used to get rid of unnecessary moisture.
It is obtained by burning raw wood waste in furnaces. With the help of a high-pressure axial fan, through special gas ducts, it is supplied to the stacks of lumber. The design of the system assumes the presence of a steam humidifier.
In the woodworking industry they use gas apparatus, operating on natural gas. They are equipped with a firebox, the temperature in which during combustion reaches 1300°C. But before entering the dryer, the mixture circulates and cools, acquiring a temperature of 100 degrees by the time it enters the chamber. The working mixture is smokeless. If the operation of such a chamber is well adjusted, then the lumber dried in it remains light. Each can accommodate four large stacks of boards. They are also used for ordinary, routine drying of coniferous wood.
For high-speed drying of building materials, electric dryers are used, which use high-frequency currents. This procedure does not last long - the drying time is only a few hours, and its quality is high. The wood dries evenly: without flaws or cracks. The amount of defects with this drying method turns out to be significantly less than with the gas and steam methods - its figure is less than five percent.
Features of heating dielectrics and semiconductors (wood also belongs to them) in electric field high frequency consist in the fact that the temperature of the entire processed material increases noticeably in a short period of time. A wet board can be heated to 100 degrees throughout its entire thickness in three minutes. The power of the current absorbed by the material is regulated by the parameters of the electric field (its change through adjustment).
Home drying of wood
In addition to industrial methods of drying wood, there are also home ones.
Using a microwave
The advantages of this method are that when it is used, tiny cracks do not form in solid wood, which can turn up to one and a half centimeters of material from each end into waste, and in some cases even break the workpiece into pieces. Under the influence of microwave heating, changes occur in the lignin fibers, due to which an object dried in this way loses its sensitivity to sudden changes in humidity.
For the drying procedure, a not too powerful, budget microwave model without unnecessary options is suitable. The main thing is that she has a routine low power. Usually it corresponds to the “defrost” mark. The chamber must be large enough to accommodate crafts or wooden pieces. Often the chamber is larger in width than in depth.
Microwave drying of wood: technology
It is more convenient to dry individual pieces entirely; some are better cut into pieces. If it is already known what they are intended for, then they are cut to the size of future products, with an allowance. It is allowed to dry a pre-processed workpiece, which must also have at least a small allowance. It should be remembered that the product may become deformed during the drying process. A round object can become more oval.
Anyone who often works with wood gradually gains experience. Craftsmen can guess what kind of reaction to expect from which type of wood, how exactly which type is deformed, and make the appropriate allowance. If you leave a processed raw piece on the table, it may burst.
During breaks in work (for example, when carving) or before drying in the microwave, it is necessary to put the product in a plastic bag.
Microwave: drying at home
Before starting the procedure, the workpiece is weighed and the weight is recorded. Wrapped in plastic bag With the holes made, the item is placed in the middle of the oven, and the minimum power is set. Processing time depends on the size of the item. Then the workpiece is cooled directly in the bag and warmed up again. The condensate from the bag is drained and the item is weighed.
The entire cycle is repeated several times until the mass becomes constant and stops decreasing.
If the item cracks in the first attempt, it is necessary to either reduce the power further or seal the ends of the workpiece. The mouthguards are wrapped in newspapers before being placed in the bag. You can also do this with other workpieces: this will reduce the likelihood of wood cracking.
After cooling, before the next cycle, the newspapers are replaced with new ones. If there are resin pockets in the array, the latter can boil, break it, and stain the oven with resin. Wrapping in paper will also help here.
If you continue the process of heating already dried wood, it can char and even catch fire.
Natural air drying of wood
This is an affordable and extremely simple method. The boards are stacked under a canopy to prevent precipitation and sunlight from falling on them. A special flat base must be prepared for them, for the equipment of which rails, logs, thick pipes or bars can be used. Lumber is laid across this base.
There should be a distance of 0.3 m between the ground and the bottom layer of boards. It is better to cover the ground under the stack with sheets of roofing material, straw or hay. The wood takes quite a long time to dry: this process can take up to several years. In warm weather, the process is more active.
The ends of the forest are covered with a special mixture containing lime. The sides of the stack are protected from slanting rain and strong winds. Special measures are taken to prevent rapid drying and cracking of the material. Spacers are laid across the boards, between the layers of dried wood, at a distance of a meter from each other: the outermost ones are located flush with the ends of the boards in the stack.
With this method of drying wood with your own hands, mandatory cracks form at the ends of the boards. For this reason, the length of the blanks should be slightly larger than the planned products. After all, after drying is complete, the cracked ends of the boards will have to be cut down. With such drying, carried out in dry and warm conditions, the remaining in - is the largest online store selling furniture, lamps, interior decor and other goods for a beautiful and cozy home.
Freshly cut wood is not used in production and construction, as it contains a large amount of moisture. This type of wood is called wet. To improve its mechanical and physical properties, a lumber drying chamber is used. In the process, biological resistance increases, the strength index increases, and other qualities of wood improve.
Wood moisture concept
The percentage ratio of the weight of the liquid contained to the weight of completely dry wood of a certain volume is called absolute humidity. The percentage of the mass of water removed (determined by two weighings) to the original weight of the wood is called relative humidity.
The degree of suitability for use is determined taking into account the relative humidity indicator. The value indicates the readiness of the material for gluing and drying; with a value above 30%, there is a danger of developing a fungal infection.
Depending on the indicator, wood is divided into categories:
- wet - with a relative humidity of more than 23%;
- semi-dry – within the range from 18 to 23%;
- dry – with a humidity value from 6 to 18%.
Drying wood in natural conditions
With this method of removing moisture, a drying chamber for lumber is not used; the liquid evaporates under the influence of atmospheric air. Dry the material under a canopy located in a draft. Sun rays the outer and inner layers of wood are heated unevenly, which leads to the appearance of deformations and cracks.
If the site does not have a drying chamber for lumber, it is well suited for drying attic space, ventilated barn, equipped shed. The material is stored in a stack, the first layer must be placed on stands with a height of at least 50 cm from any durable material. Rows of lumber are laid with dried slats, all subsequent boards and logs are placed above the previous blanks to create vertical air wells.
Logs sawn lengthwise and finished boards are placed inside up to reduce the size of the deformation. For the same purpose, a stack of wood is pressed from above with a heavy load. Due to the formation of cracking at the ends of the workpiece when drying the material, select the length of the workpiece to be 20-25 cm longer than the intended part.
The ends of the lumber are carefully treated with paint on oil based, drying oil or hot bitumen to prevent cracks. Before stacking, the log trunks are cleared of bark to reduce the likelihood of wood beetles breeding. Removing moisture from wood naturally referred to as economical methods.
Solar wood dryer
The second method, the cost of which quickly pays off, is drying chambers for lumber. The manufacturing drawings are quite simple; you just need to understand the operating principle of such a device. The chamber is an assembled plywood or metal container, the roof of which is made of transparent materials.
The size of the glazed roof surface is calculated depending on the total horizontal area of all lumber laid for drying. The area of the transparent coating should be one tenth of the total surface of the boards. The roof of the building is made pitched, the amount of slope depends on geographical location terrain. In cold northern regions, where the sun does not rise high above the horizon, the roof slope is made steep. The southern sun warms up the gently sloping surfaces well.
How to make a drying chamber for lumber?
The frame of the building is made of metal or timber treated with an antiseptic under pressure. The lining of the walls and floor of the chamber is made of moisture-resistant materials, the fences are insulated mineral wool or hard foam boards. Internal surfaces The walls are treated with water-repellent compounds, aluminum powder is applied to them, and then painted black.
Fresh air blowers should not contain blades made of plastic, fusible materials. If the drying chamber for lumber is not used constantly, then the room is used for drying herbs, vegetables, berries or a seasonal greenhouse. After laying all the wooden blanks for drying, a distance of about 30-40 cm should remain between the stack and the wall on all sides.
Drying wood in artificially created conditions
When removing moisture in a natural way Relative humidity readings of about 18% are obtained. To improve the value, lumber is dried in drying chambers, where temperature and speed are regulated forced submission air and its humidity.
Basic equipment for dryers
Whatever type of forced wood drying chamber is used, standard groups of equipment are allocated for all.
Transportation equipment is designed for loading and unloading logs or boards into the drying room. Includes machines and mechanical devices for storing workpieces in a stack or package, and carries out raising and lowering of lumber.
The thermal equipment of the chamber serves to raise the temperature of the internal air in the chamber and consists of many systems that determine the interconnected work of producing and transferring heat. These include heat exchange tanks, heaters, pipes for the passage of steam or hot water, condensate removal devices, shut-off valves and control devices.
The fuel is gas and liquid fuel. For small volumes of work, a drying chamber for wood-burning lumber is equipped. The coolant is saturated steam, water, gas obtained from combustion of the furnace, and organic fillers of the system that have a high boiling point. Electric heaters are widely used, where current energy is converted into a thermal component.
Circulation equipment is designed for the organized movement of air masses in the drying chamber. The elements of the system are fans, injectors and joint installations of these elements. To increase the efficiency of wood drying, automation of lumber drying chambers is used.
Drying chamber fence
To isolate wood from action environment install a chamber fence, which consists of a floor, ceiling, walls and intermediate partitions. Requirements for partitions:
- should not allow steam to pass through;
- fences must have low thermal conductivity;
- must have a long service life.
Fences are made separately from various building materials or can be prefabricated with a set of standard metal elements.
The first type of cameras has a longer operating life, but differs more for a long time commissioning, which is not always justified. Prefabricated metal frames They are installed quickly, they are equipped with control and thermal devices, but the steel is subject to the destructive effects of wet and thermal conditions.
Working principle of vacuum drying
After stacking the wood, close the chamber door hermetically and begin the drying process. By using automatic devices Some of the air is removed from the chamber until a pressure of 8-10 bar is created inside. Thanks to this scientific approach, the moisture released from the wood moves faster from the center to the outer fences of the chamber, thereby ensuring uniform and high-quality drying. This is how vacuum drying chambers for lumber work.
Making a drying chamber yourself
Private developers dry wood in their yard; for this purpose, they install a drying chamber for lumber with their own hands. Its installation will require a large room, a heat source and a device for distributing air between drying packages of wooden blanks.
You can, of course, purchase used lumber drying chambers, but the degree of wear cannot always be determined correctly; it is much more profitable to arrange a room for drying wood yourself. This is an opportunity to get excellent results at low cost Money.
Construction stages
You will need material for the frame, usually metal racks from a corner or channel; a wooden beam is used after careful treatment with an antiseptic. Metal sheets, moisture-resistant plywood panels, and profiled steel are used as wall coverings. Thermal insulation is carried out using mineral moisture-resistant wool and polystyrene foam.
Before construction begins, the location of one dryer or several is determined, which serves as a plan for the device concrete foundation. The foundation is made for the stability of the structure and uniform distribution of the load on the ground. If a ready-made railway container is taken for the camera, then four are made columnar foundation under the corners of the car.
The metal frame is assembled using welding or bolted connections. When installing, check verticality and horizontality building level, trying to strictly adhere to geometric dimensions. After securing the frame in the installation position, they begin to cover the outer walls, simultaneously inserting doors and ventilation windows.
The thermal insulation layer of the floor, walls and ceiling must be at least 12-15 cm, the base is insulated from moisture roll material. After this, the chamber is checked for leaks. To lay the first layer, stationary supports made of metal or wood are installed. Install a heat source, usually a powerful fan heater, position it so that the direction of the hot air is parallel to the lying boards.
Drying wood is a necessary condition to obtain quality raw materials. Building a house or making fillings for openings from damp lumber is fraught with distortions and damage to integrity. In order to carry out work with wood without problems, you need to take seriously the removal of excess moisture from the material.
7 reasons for every craftsman to have his own wood dryer
The better the wood is dried, the better the finished product. Therefore, you spend a lot of money on drying wood. You give only to trusted places and patiently wait for the end of the process. But this stage can be accelerated and made less expensive. And even get 20% more output quality material! If you have your own dryer for FlexiHIT boards - our production.
Why do you need a personal FlexiHIT lumber dryer?
- 20% more quality material! The result is flawless wood without deformations, internal stresses, warping or cracks. 15-20% more workpieces than with industrial drying. What is the reason? Drying occurs as naturally as possible. Infrared radiation is as gentle as the rays of the sun. But thanks to a special design and innovative solutions, it dries faster and more evenly.
- From one board to 10 cubes. For the first time in the history of professional drying, you can dry any volume of wood! From one board to large stacks. There is no longer any need to waste money on drying or accumulate a large volume of wood to load. At the same time, the cost of our kit is several times lower than the cost of a drying cabinet.
- Automatic drying process. The drying procedure is absolutely comfortable and does not require your participation. After loading the material, the wood dryer is completely autonomous - you do not need to constantly monitor the wood drying process as when drying in an induction dryer. No special place required either! Dry the wood either outdoors in the courtyard or indoors. Anywhere and unattended.
Material ready in 3-7 days. Assembling a wood dryer does not take more than a day. Installation is simple, thanks to detailed instructions. The drying time depends on the type of wood and the amount of moisture in it. On average - from 3 to 7 days. Drying period for soft wood, the drying time will be from 3 to 7 days to 6 - 8% humidity, for hard wood from 13 to 20 days to 6 - 10% humidity. Stable result - up to 8% humidity in 7 days!
Calculator for calculating the cost of a wood dryer
Wood dryer price:
1. Infrared cassettes: 29,700 rub.
2. Control cassettes: 12900 rub.
3. Control panel: RUB 12,002.
4. Cabling: RUB 8,286.
5. Lathing: 1257.76 rub.
Total: 64,146 rub.
The price calculated by the calculator is approximate, to clarify the price of a wood dryer
4 reasons why you shouldn’t make a dryer yourself
- For a long time. A lot of time will be spent on experimentation, design and construction. It took us 10 years to create the dryer, having behind us other successful developments in the field of infrared heating.
- It's a chore. It will take a lot of time to debug the dryer so that the resulting lumber is of high quality. We have conducted thousands of experiments.
- Risky. You may never be able to create a normal dryer. This is not an easy matter, believe us.
- Expensive. There is a possibility that the dried lumber may be spoiled at first, which will lead to even greater financial costs.
FlexiHIT - 3 years of improvements!
- Our wood dryer has been improved for more than 3 years. You don't have to go through this journey on your own. It is enough to assemble the device according to detailed instructions.
- There is a lot of material on the Internet about IR devices created by amateurs - and they assure you that high efficiency process. But there is no convincing evidence.
- We have been doing IR heating for ten years. We manufacture functional equipment for industry, construction, and medicine. We have serious production facilities and professional designers. However, developing the dryer did not come easy to us. A high-quality dryer cannot be created “on your knees”!
How does the FlexiHIT wood dryer work?
As a result of 10 years of testing and development, the board dryer is a set of special thermoactive cassettes with a thickness of 1.5 mm. The cassettes are placed in a stack of lumber prepared for drying in a certain sequence.
Wood drying occurs by heating the wood with infrared rays. This drying method does not require a coolant. Therefore, there is no need to maintain its precise parameters, ventilation and complex automation.
The operating life of the heating cassettes, subject to instructions and careful operation, is at least 3 years, 1-year warranty.
Video of the FlexiHIT dryer and instructions for assembling and drying wood
Comparison of modern wood dryers and drying technologies
| Vacuum | Induction |
Aerodynamic |
Condensation |
Convective |
FlexiHIT dryer | |
|---|---|---|---|---|---|---|
| Load capacity | from 4 to 20 m³ |
6-9 cubic meters of lumber |
6,12,15 or 20 m³ |
-
|
from 8 to 200 m³ |
Any minimum, from 1 log |
| Difficulty in installation and connection | Difficult |
Difficult |
Difficult |
Difficult |
Creation of foundation, chamber, rail track, power supply and pipelines |
Average |
| Control | Complex automation: you need to monitor coolant parameters and pressure |
Requires regular monitoring to prevent wood fires |
Automatic |
Automatic |
Delicate, attentive. Requires compliance with safety regulations |
Automatic Does not require control, but if necessary it is possible to influence the process |
| Drying time | Pine boards with relative humidity 50% to humidity 8% 16-18 hours |
Pine timber 200x200 mm with a moisture content of 50-70% up to 18% in 22 hours |
Pine boards 25 mm thick dry for 2-3 days, and 50 mm boards - 3-4 days to a humidity of 8% |
40 mm pine board 9 days, 50 mm - 12 days, 70 mm - 18 days |
From 3 to 6 days |
From 3 to 7 days |
| Size | Parallelepiped-shaped unit with a loading volume of 4 m³ - 4800x1700x2005 mm |
Drying chamber for 6-9 cubic meters of lumber - more than 6 meters |
Chamber for 9 m³ - 7 meters, for 20 m³ - almost 14 m |
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Chamber for 8 m³ - 7.0x2.0x2.4 m |
One thermoactive cassette 1230x650x1.5 mm. A standard set for drying 1 m³ of lumber includes 12 cassettes with a total weight of 69 kg. |
| Dryer weight | Without aluminum plates 2300 kg |
9 tons |
Impressive |
Minimum 120 kg |
Impressive |
With the sheathing, control panel and cabling, the weight of the equipment does not exceed 130 kg. |
| Coolant | Flow of air heated from heaters |
High frequency currents 915-2500 MHz |
Hot air blown by a fan |
Hot air flow from heaters |
Flow of air heated from water heaters |
Infrared rays (sun rays) |
| Mains voltage | 380 V |
380V, 50Hz |
380 V |
380 V |
AC power 380/350 |
operates on 220V/380V network |
| Electricity consumption per 1m3 | 15-37 kW |
200-230 kWh/m³ |
240 kW/m³ |
140 kWh/m³ |
280 kWh in summer and 340 kWh in winter |
1.5-2.5 kW |
| Transportation | Rail or road container | Special equipment | Special equipment | Special equipment | Special equipment | Easy to transport by car |
| Place for installation of equipment | Indoors | Indoors | Indoors | Indoors | Indoors | Both indoors and outdoors |
| What is it suitable for? | For industrial production | For industrial production | For industrial production | For industrial production | For small volumes of wood |
|
| Possibility of making a dryer custom size | No | No | No | No | No | Eat |
| Cost of drying 1 m3 | from 600 to 1400 rubles for the entire drying period | |||||
| Price | From 500 thousand to 1.5 million rubles. | From RUB 1,300,000 | From 410,000 rub. | From 250,000 to 1,000,000 rubles. | From 350,000 to 4,000,000 rubles. | From 62,888 rub. |
Stack fencing
The stack shell consists of polystyrene insulation located under the stack and on its top, as well as a reflective fence covering the perimeter of the stack. The casing is not supplied and can be designed to fit specific stack sizes.
You can also familiarize yourself with (one of the design options).
Examples of correct and improper installation stacked wood drying cassettes
Do you have any questions about drying lumber at home using a FlexiHIT dryer?
When steaming, moisture evaporates from the middle of the wood. I have no idea how this process occurs when wood is locally heated. I also don't understand why you can do without fans.
Why is it steamed? saturated steam when processing wood? In order to saturate the wood with moisture and dry evenly at a speed at which moisture will migrate from the inner layers to the outer.
When using low temperature infrared emitters moisture is already “expelled” from the inner layers, which leads to intensive selection (condensation) of water in the first quarter of the drying process and removal of moisture. No steaming needed.
But in chambers it is needed because the coolant is hot air, and it does not penetrate into the wood; it dries slowly, starting from the surface. Therefore, you can’t rush, you need to wait for the water to capillary from the center to the surface.
Ultrasound, high-frequency frequency, and induction tear wood - it’s clear why. I think that your method should tear no less, but even more. Are you also trying to heat the wood from the inside?
We have a soft mode, this is natural drying, so there will be no tearing. This refers specifically to the rupture of pores, capillaries, non-surface ruptures and cracks that occur due to uneven drying of the board.
Do you have experience organizing a lumber dryer in the basement? What pitfalls might there be? A bath for collecting water is planned under the drying area. The temperature in the basement is above zero.
“Pitfalls” depend on the volume and frequency of drying. We must expect that not all the water condenses - some comes out as steam, and if there is no good ventilation, the basement walls will get wet. With constant operation of the wood dryer, the basement may gradually warm up, and heat outside the stack shell will change the dew point, condensation may decrease. Ventilation is required if the room is small. Up to 300 liters of water can come out of a cube of pine, 500 from oak.
How to operate a wood dryer winter period? How to control and regulate air humidity? How high is the stress in the material after drying?
Steam collects in the chamber and reaches such a concentration that drying stops and the steam must be removed. Paradox: the chamber is needed to retain air, but it increases humidity. Therefore, wood drying is possible when the following mode is used: “heating the air - ventilation - pumping out moist air - heating again.” And when acting directly on water without a camera, everything works out easier. We use isospan to ensure uniform humidity in the stack and speed up the drying of the wood.
The problem of maintaining optimal moisture content in lumber is relevant both among builders and among those who like to make something in their own carpentry workshop. Drying wood at home allows you to save a lot on its purchase, because dry raw materials are always more expensive than wet ones.
By the way, if you don’t have time for construction works, then you can dry wood at home or in the country even under atmospheric conditions.
Some owners adapt ready-made haylofts, sheds or other suitable buildings for these purposes. This is the way out of the situation that one of our forum members found.
Timakval member FORUMHOUSE
I used the yard attic (former hayloft) size 10*5 m for drying. I laid it out, as it should, through spacers in each row. Total 3.5 cubes of boards of different categories. The advantages of this drying place are always shade, finished roof and is well ventilated. Took it last May different sizes boards, bars and beams - blanks for small construction. The boards were too heavy to lift due to moisture. During the time they were lying in the hayloft (1.5-2 months) they dried to fluff, they did not curl or bend.
Drying under atmospheric conditions is a rather lengthy process, and since we have decided to take a comprehensive approach to this issue, let’s look at the sequence of building a home dryer with our own hands, which allows us to more effectively achieve the required humidity levels. As suitable premises We suggest you choose a building of the required size, and after that you can start working. The room can have dimensions of 2*3 m or 4*3 m (more is possible). It all depends on your needs and the scope of your activity. But when choosing a building, you should remember that there should not be much free space left in the dryer. After all, drafts and chaotic air movement negatively affect the quality of wood.
DIY wood dryer
The room chosen for arranging a homemade dryer must be heated by a stove or a specially installed fireplace. It is good if a heater is pre-installed in the room. If there is none, then be sure to leave room for it.
This is the project for making a home dryer suggested by a member of our forum.
Nikolay Valen member of FORUMHOUSE
There is a large garage with water heating; a potbelly stove using wood and waste is installed as a boiler. There is a pipe with a diameter of 800 mm and a length of 2.2 meters (former ventilation duct With industrial enterprise). The idea is as follows: install sealed covers on both ends of the pipe, leave fittings with a diameter of 150-200 mm for the supply and removal of hot air. The air is heated by a radiator (this can be a car heater). Air supply - table fan. 0.3-0.5 cubic meters of lumber are loaded into the pipe, the stove is heated (the coolant temperature reaches 90 degrees, I think that the supplied air can actually be heated to 50-60 degrees).
If you have chosen a room too large sizes, then the space planned to be used for homemade dryer, should be made insulated and sealed. For these purposes, wooden partitions are made; insulation, brick and other materials can be used to create your own microclimate in the dryer. Do not forget that it is necessary to leave a window in the chamber for ventilation and front door. After all, we shouldn’t end up with a hut without windows and doors.
Fans installed in the drying chamber will help create forced air flow and make the drying process more efficient.
mfcn FORUMHOUSE member,
Moscow.
It is advisable to place fans on the floor to the side of the stack so that the blowing is parallel to the spacers. Remember that when drying wood, you need to evaporate about several hundred liters of water from each cubic meter of wood.
To place lumber in the dryer, special shelves or flooring should be installed. These products can be made of metal so that the structure can withstand relatively large loads. Wood should be dried to levels corresponding to 8–12% humidity. Its measurements are carried out using a special moisture meter.
Drying wood is necessary following certain rules. Otherwise, the material will be hopelessly damaged and cannot be used in construction. To do this, the wood must be stacked. And between each new layer, spacers made of boards of the same thickness should be placed. Wood of any species, stacked in neat stacks, will never suffer from fungal infections and will retain its integrity and excellent consumer qualities.
Lao Czy member FORUMHOUSE
The spacers need to be made higher for better air ventilation between the boards. They will dry out better. You can place your cut 25*30 or 25*40 cubes on edge. The reason for limiting the height of the stack is to prevent the boards from being driven by a “helicopter blade”, secure the topmost layers of boards in the stack with self-tapping screws. I have been storing my boards using this method for the 3rd year at my dacha in the Moscow region. They are in excellent condition!
Gaps should also be left between boards located in the same row. This will ensure unhindered air movement inside the stack and improve drying quality.
Wood drying chamber project
Wood can be dried quickly and efficiently in well-equipped and free-standing drying chambers. Construction of such a chamber on the scale of a dacha or suburban area is not always advisable. After all, this type of construction will be very expensive, and its construction will take a lot of time.
The construction of such a premises can well be called the implementation of a full-scale construction project. You cannot avoid labor-intensive operations associated with pouring the foundation, erecting walls and installing complex equipment.
How to make drying for wood can be understood from the diagram.
DIY chamber drying
Such a mini-wood dryer requires the placement of not only basic equipment (heating and ventilation), but also additional automatic control systems.
Operating modes of the drying chamber
A chamber dryer does not require high heat during normal operation. A full cycle Work associated with drying one batch of wood can be divided into several stages.
The first stage lasts from 15 to 20 hours. During this period, the air in the chamber warms up to 45С. The ventilation does not turn on, and condensation forms on the walls of the room.
The second stage lasts about 48 hours. It involves connecting ventilation and heating the air in the chamber dryer to 50°C.
The third stage lasts until the required final moisture level is reached in the internal structure of the wood (8...12%). At this time, the air temperature rises to 55 C, the exhaust dampers open completely, and the fans operate at full power.
Once the humidity reaches the required levels, the heat supply should be stopped. The fans should remain on for another 24 hours. As a result of this heat treatment, you will receive dry wood, completely ready for use during carpentry or construction work.
You can get acquainted with the practical developments of our forum members regarding the correct construction of a stack in the “” section. Those who want to learn more about the technology of drying lumber can visit the “” section. For those who want to see a master class on wood aging technology, we recommend watching the corresponding video.
