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Kiln Controls

Tech Update Editor: Mel-Lynda Andersen



The Cathild control system CH12 PC is runs using Windows ‘95 program. This new generation of regulation changes the drying program, following the reaction of the lumber to the drying process. Cathild CH12 PC measures the moisture content of the lumber with a weight system and probes. With this information, the computer system changes the program automatically (increasing or decreasing the temperature, and increasing or decreasing the relative humidity of the air) to reach the quality and drying time that the kiln operator needs. This computer system is the first generation of kiln control system to help the operator to optimize his drying programs.


Northern Milltech Inc.market01.jpg (14579 bytes)

With a view to maximizing kiln performance, increasing attention is being paid to limiting moisture content deviation before the lumber even leaves the sawmill. The NMI Moisture/Density sorting system works by pre-sorting the lumber according to drying characteristics, which reduces MC deviation at the planer and results in increased grade recovery and decreased trim loss. These factors, combined with reduced kiln times, increased planer production and ease of installation, have made the NMI system the system of choice for sawmills across North America, claims the manufacturer. Once of the best ways to enhance the performance of a kiln controller is to provide a kiln operator with a detailed analysis of every charge leaving the kilns. The KMI100 inline planer moisture detector, through the use of a unique bar coding system, tracks the moisture content and standard deviation of every load. This information is combined with the kiln number, charge number, schedule number and package location within the kiln and can be retrieved at any time.


Frank Controls

Frank Controls offers the original closed loop dynamic drying process. Where conventional controllers use a scheduling scheme, the Frank Control system continuously monitors and controls the temperature and relative humidity in the kiln, with changes to the process during a cycle. The process will improve grades and decrease energy use in any kiln, says the company. A new component is the digital temperature bulb, which offers accurate and reliable temperatures, compared to an RTD-type bulb. RTDs measure by resistance, often fluctuating and providing inconsistent readings due to wiring faults within a humid kiln environment.


Irvington Moore

A new in-kiln weight scale system from Irvington-Moore measures and records the weight of an in-kiln sample board more than 50 times per second, providing real-time data on actual drying rates. The system also allows the kiln operator to make specific adjustments based on the current data. The technology enables levels of quality previously unattainable in the lumber industry, according to Irvington-Moore. The system eliminates the use of probes and the need for periodic sampling of board weights and generalized drying schedules. By capturing and recording real time data, the control system can make instantaneous changes in the drying schedule. The scale unit is compact, weighing only about 15 lbs. The Irvington-Moore in-kiln scale system subjects the sample board to all of the subtle air flow variations that can occur during the typical drying cycle, ensuring accurate data, even when actual drying circumstances are unique.

The in-kiln system eliminates the need to enter the kiln during the drying cycle. Since the data is collected automatically from the sample board in the in-kiln scale system, there is no need for manually weighing sample boards to check for dryness. The in-kiln scale system can be integrated with the Irvington-Moore Kiln Boss Control systems. The digital interface is received directly into the Kiln Boss program and plugs in directly to kiln control parameters.


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According to its manufacturers, true zone control is achieved with the Delta T kiln control system. Most kiln controls attempt to control drying in a kiln by comparing individual zone temperature drops across the load (TDA L), with the overall average T DAL. Such systems are subject to error because T DALs, to be comparable, must have equal air flows and entering air temperatures. Since such conditions are seldom if ever met, true zone control is not achieved, says the company, adding that in fact, error can be introduced. The Delta T kiln control system uses drying rates which are comparable between zones and can be beneficially used in a true zone control system. When the Delta T determines that the lumber fibre saturation point has been reached, zone temperatures are adjusted in order to bring all zones to the same endpoint MC. In addition, the Delta T provides a screen with 10 selectable shut-down parameters for use in maintaining the target MC.


 Better Built Dry Kilns

Better Built Dry Kilns are now supplying Lignomat computer controls as standard in all of their installations. The Lignomat computer controls feature 900 Mhz wireless communications between transmitters and receivers. The moisture-sensing pins and the EMC wafers are now available wireless; there are no more cables to pick up transient signals or to trip over. The wireless technology is available for kilns, pre-dryers and even for air drying yards.


M-Sprague Inc.

In conventional venting, moisture-laden air is reheated before it is vented. Cold make-up air is introduced where it cools the previously heated air. It doesn’t make sense to heat air then throw it and the energy away, says the company, but nearly all kilns operate in this manner. With an Ultra Vent Plus system from M-Sprague, only the moisture-laden air is exhausted from the kiln. Its heat energy is extracted by an air-to-air heat exchanger, which preheats the incoming make-up air by up to 100F before it enters the dry kiln. Each Ultra Vent Dry Kiln Heat Recovery and Vent Optimization system is a totally self-contained, patented venting system, and includes all ducting. It does not rely on the dry kiln fans for air flow control.


Custom Dry Kiln Company

The Custom Dry Kiln PLC operating system combines ‘Industry Standard PLCs’ with non-proprietary Windows‘ Off the Shelf’ PLC software, resulting in what its developers call a user-friendly program that maximizes productivity and reduces energy usage. Features include ‘off the shelf’ PLC software, user’s choice of PLCs, choice of automatic or manual functions such as PLC temperature control, automatic schedules, location via modem, auto on and off, auto or manual temperature control, auto or manual solenoid control, auto or manual alarm monitoring with page-out feature, and fully modulated dampers, valves and burners.

According to the company, advantages of this system include in-kiln probes, online help through Custom Dry Kiln’s web page, remote access and a variety of reporting capabilities, such as historical strip charts, archiving of kiln data, screens that provide detail, overview, historical and schedule information, and instant onsite support 24 hours a day, year-round.


American Wood Dryers, Inc.

American Wood Dryers, Inc. has been selected by Delmhorst Instrument Company as an OEM supplier of their Loadmaster In-Kiln sample weighing system. This ties in with the company’s Drystar computer control system, which provides a comprehensive and flexible solution for dry kiln control. Principle features of the Drystar system include industrial quality computers complete with Windows ‘98 graphical operator interface, hard disk storage and 3.5" floppy disk drive. For multiple kilns, all Drystar computers are identical, with any one acting as host to the others. A single computer malfunction affects only a single kiln. Temperature and humidity control is fully modulating, using position feedback from each valve and a vent actuator to provide the highest level of accuracy and confidence. Easy-to-use graphical interface software features familiar pull-down menus and pop-up dialog boxes. Kiln operation can be either pre-programmed time-based drying schedules or you can simply use manual set-point control as with your old controllers. Also, built-in trouble-shooting tools pinpoint malfunctions and eliminate guess work. Drystar options include electronic scale with interface to compute and record moisture content of oven-dried sample boards; resistance moisture probe circuits for automatic moisture-content-based schedule control or in-kiln moisture monitoring; integrated variable-frequency fan speed control software; and remote monitoring and control via high-speed modem.


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Sechoir has developed two new products: MEC’s high-temperature cross-shaft kilns and MEC’s direct fire kilns. High-temperature cross-shaft kilns are suited to the needs of softwood lumber producers. They shorten drying cycles and consequently increase the annual production of wood dried. Direct fire kilns, on the other hand, have been designed for a broader-based clientele, including both hardwood and soft-wood lumber producers. They are energy-efficient, cost little to install and are the first choice of producers who have not yet acquired a boiler system. The holding capacity of MEC’s front-loading kilns is tailored to the customer’s needs. Each kiln has two rear doors and passages located near the ventilators that facilitate maintenance of the drying cells. Each door consists of an aluminum frame and waterproof insulating panels equipped with a simple, solid mechanism to make handling easier. Several heating systems are available for each kiln. Another of Sechoir MEC’s product line includes the VIP automation system, which can control up to 99 kilns at once. The WSWD weighing system consists of an electronic scale on which a part of the load is placed. As this control load dries out, the resulting loss of weight is monitored and used by the computer to conduct the drying process of the total load.


Coe Manufacturing Co.market03.jpg (11061 bytes)

The current state of the art in dry kiln process controls is the Coe Series 22M-2000 Kiln Control System, which includes PLC control of the kiln operations and a PC provided for the operator to develop schedules, and to monitor and record the drying process. The operator has the ability to store up to 100 schedules for easy recall and application. The Series 22M-2000 allows for control of the drying process based on entering or exiting air, TDAL, moisture content measurement or by the use of load cells. Drying schedules are advanced automatically based on TDAL, moisture content or time basis.


SII Dry Kilns

When an SII computerized control is added to your kiln, a range of new options becomes available: remote control of the kiln, i.e. monitoring or controlling the kiln over the phone using your home or portable computer; history-logging; reporting; and centralized control and operator alerts using a pager. The Kiln Dry line of controllers offers a range of options for advancing the drying schedule based on the drying progress of the lumber. Options include weight-based drying using an external scale; the new weight-based system which uses in-kiln, on-line sample monitoring; electrical MC probes inserted into the drying wood; time-based drying; and TDAL-based control.


Salton Fabrication

Salton Fabrication announces its new kiln control system, Winkiln, which incorporates colourful, easy-to-operate screens and a multi-tasking Windows operating environment. According to the manufacturer, Winkiln’s aim is to increase kiln productivity simply and dependably. It can control up to 20 kilns, includes 60 drying schedules, and works with any type of kiln and heating system, including direct or indirect fired, single or double track, and side-loading kilns. Its data management system allows a kiln operator to track drying variables and recall information on demand. The company claims that Winkiln’s ability to control up to 12 zones in a multi-zone configuration means better quality lumber and higher profits. Winkiln uses industry-standard equipment, including Opto ZZ hardware, a PC with a Pentium II 350 processor with 64 Meg of RAM and Windows NT 4.0. Technical support services include a 24-hour-a-day, seven-day-a-week online diagnostic service, land scheduled monitoring and program upgrades by telephone or modem connection to Vancouver, Portland or Montreal.


Carter-Sprague, Inc.

CSI Carter-Sprague, Inc. is now providing Kiln Controls 32—the Computerized Kiln Control System designed and manufactured by ACS Automated Control Systems. Kiln Control 32 is a lumber dry kiln control system designed specifically for Microsoft Windows 95 and Windows NT. Kiln Control 32 provides complete temperature and humidity monitoring and control for your kilns. Multiple kilns can be controlled from a single computer system. The Windows 95 and NT interface makes learning and using Kiln Control 32 simple and enjoyable, says the company. Logged data can be printed out for historical and data trending purposes. The production report includes a notes column, which allows users to enter their own information for each report entry. The live graph editor simplifies schedule creation by providing immediate feedback when creating drying schedules. Set points are graphed as they are entered. Schedule advancement can be dictated by time alone, or on having achieved the last setpoint temperature. Manual set-points may be entered to over-ride schedule control. All control options are invoked by a simple mouse click.



With over 25 years experience in wood-drying technology, InComac manufactures a complete line of conventional, dehumidification, direct heating and high-temperature dry kilns. These systems provide high-quality system and chamber design, construction and integrity to suit varying needs in drying all types of wood to the highest possible quality and efficiency. They are all backed by a full line of service and technical support.



The new Wireless Moisture Measuring System from Lignomat uses wireless probes for accurate and easy moisture and temperature monitoring. Any materials which can be measured with a hand-held moisture meter can also be monitored with the Wireless Probe system. The transmitter is connected via a short cable to sensors which detect both wood moisture and relative humidity. Each transmitter converts the measured values into digital readings and transmits the information by radio frequency to a receiver. If a straight line of sight exists, the transmitter can reach up to 1,000 ft. Through lumber the reach is approximately 60 ft., reports Lignomat. Software is available for PCs to monitor receiver stations, creating a table with time stamp and data from the transmitter stations. A Microsoft Access database can be used to analyze the data. Lignomat has installed hundreds of wireless probes in dry kilns and drying yards since their introduction in February, 1998. Any standard IBM-compatible desktop PC can be used as a host. According to the company, the benefits of the LMS-16G Windows-based graphical interface with the host PC include more flexible display of drying parameters; increased accuracy for wood probe readings above the fibre saturation point; software that allows entering sample weights; and data from LMS-16G control system can be transferred to other database programs.


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The Loadmaster Kiln Control System from Delmhorst provides accurate, realtime MC data to control the process and help reduce drying time, according to the manufacturer. Electronic load cells are permanently mounted on sample board holders and attached to the inner walls or set in the plenum area of the kiln. Once the charge has been started, the sample boards are weighed automatically and continuously, providing the operator with real-time data on actual sample weight and accurate moisture content readings. All calculations of weight and moisture content are performed by the software. Optimum set points are determined and updated every 15 minutes, advancing the schedule gently and gradually, not in sudden step-like adjustments, explains Delmhorst. The result is a more uniform drying curve and faster drying time, with less degrade. Real time weight measurements allow the operator to overcome the limitations of time-based schedules and indirect electrical methods. This approach also eliminates the need for daily time-consuming manual checking, effectively increasing kiln operator productivity says Delmhorst.


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Using electricity to power its 150-kW amplifier, the Heat Wave 30.150 Radio Frequency Vacuum kiln provides the most energy-efficient drying technology currently available on the market, claims the manufacturer, Heat Wave Drying Systems Ltd. An easy-to-use touch-screen command centre is at the heart of every Heat Wave Kiln; dial in your desired final moisture content and Heat Wave’s end-point detection system monitors moisture removal and performs an automatic kiln shutdown. Additional features include pre determined drying schedules and an exclusive compression loading system suitable for hardwood and softwood species. Products particularly suitable for drying by the Heat Wave 30.150 include hardwoods such as aspen, birch and red alder, and softwoods such as hemlock and Douglas fir.


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According to the manufacturer, each Mahild dry kiln is specifically designed for your lumber and location. Mahild’s standard dry kiln is the classic kiln for all lumber. The high-temperature kiln provides the fastest drying times with temperatures up to 140 C. Steaming chambers have been designed for direct or indirect steaming processes, and Combi-kilns offer steaming and drying in one kiln. Mahild low-energy dry kilns can be fired with steam, hot water or Thermo-oil; gas-oil (direct-fired) systems are also available.

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This page last modified on Tuesday, February 17, 2004