ThermoVent™ Power Venting and Heat Exchange System *

Home Page | Housing | Roof Curb | Fan Safety | Heat Exchanger | Controls | Unit Cost | Photographs | Description | Advantages | Technical

The ThermoVent™ system augments the existing gravity vents in a conventional dry kiln, it does not replace them.

Under most conditions if the ThermoVent™ system is properly applied, it will handle most of the venting load. If the ThermoVent™ system is running at 100% speed, however, and the wet bulb temperature (or EMC) is still too high, your existing vents will come into play as needed to get the humidity under control. Should this happen frequently it is a sign that perhaps another ThermoVent™ unit is called for.

The unique feature of the ThermoVent™ system is that VF drives are used to precisely control the speed of the intake and exhaust fans to match the venting conditions needed for optimum humidity control. Heat recovery is shown on a chart at the bottom of the page.

Other charts comparing dry and wet bulb temperature, reheat air temperature, outside air temperature, vent percentage and projected energy saving in $ per hour are available in PDF format via e-mail. Actual photographs of the system in operation are available also as JPEG images and as pop-up images on this page. Predictive charts can be prepared for your application based on your specific schedules, type and thickness of lumber, drying profile of average or actual MC loss per hour and your actual heat energy costs.

For special situations, the ThermoVent™ fans can be used together to provide 100% exhaust (as when evacuating steam after a conditioning cycle) or 100% intake (to rapidly cool down the kiln to enable emergency maintenance, for example). Each ThermoVent™ unit can handle the venting requirement for 25,000 to 50,000 board feet of lumber, depending upon the schedules and temperatures involved. The ThermoVent™ units are modular, located on top of the kiln over the kiln circulation fans. No distribution ducts or diversion dampers are required.

Housing
The ThermoVent™ housing is fabricated of 16 ga. stainless steel sheet with 2 1⁄2" of Thermax insulation for an insulation value of R-20. Structural components are made of heavy weight extruded aluminum materials.

Roof Curb
Each ThermoVent™ unit is attached to the kiln with a stainless steel roof curb. The roof curb acts as a seal for the ThermoVent™ and the kiln roof panels. The roof curb is secured to the kiln frame giving the ThermoVent™ a solid structural base.

Fan System
Each ThermoVent™ unit includes two aluminum reversible propellers with 1 1⁄2 horsepower VF & kiln duty motors, one for incoming air and one for exhaust air from the kiln. When the kiln fans reverse the fans in the ThermoVent™ automatically reverse also.

Heat Exchanger
The heat exchanger is a flat plate air-to-air type with no moving parts. It is made of aluminum sheet with a baked epoxy coating and can operate over a range of –40° F to 400° F.

Controls
Controls for the ThemoVent units include a VF drive for each fan in a wall-mounted enclosure and include a circuit breaker, PLC and cooling fan. The controls modulate the venting of the kiln by varying the speed of the fans throughout the drying cycle. They can also be set to evacuate air from the kiln by running both fans in the exhaust position or push fresh air into the kiln during kiln maintenance.

Unit Cost
Each ThermoVent™ unit costs $21,000.00 complete with the above components FOB our factory. Installation, including electrical components, is available for $4,000.00 per unit.

Photographs of ThermoVent™ Power Venting and Heat Exchange System

DESCRIPTION

The ThermoVent™ power venting and heat exchanger system from American Wood Dryers Inc. is designed to significantly reduce energy costs by providing optimal kiln heat recovery. It also reduces drying time by preventing the loss of circulation air. This ensures consistent air velocity through the lumber load during heavy venting for greater product uniformity and, in most cases, improved lumber quality.

ADVANTAGES

Energy Saving - The system uses hot, wet exhaust air to heat the cooler intake air. At 100 percent output this can recapture from 400,000 to more than 800,000 BTUs per hour of what would otherwise be wasted energy.

Consistent Temperature - Intake and exhaust fans modulate speed to maintain constant and precise wet-bulb temperature. When the main air-circulation fans reverse, so do the intake and exhaust fans.

Original Vents Still Active - If the venting load is greater than the fan capacity at 100 percent speed, the original gravity style vents will come into play as needed. If this happens frequently, it is an indication that another ThermoVent™ unit should be considered.

Large Capacity - A single unit can supply the power venting and heat recovery needs for up to 50,000 board feet of lumber, depending on schedules and temperatures used. ThermoVent™ Power Venting and Heat Exchanger System*

Three-mode Operation - Includes normal heat exchange mode, full exhaust to evacuate all ambient kiln air (after steaming, for example), and full intake for emergency cooling (to enable maintenance, for example).

Flexible and Simple Design - Can be configured to fit most major manufacturers’ kilns and ensures very low maintenance costs.

Fast Return on Investment - Payback for the initial purchase cost can be realized in as little as 12 months through saved power bills. Government energy-savings tax credits may be available for many locations.

 

TECHNICAL INFORMATION

Construction - Tough, corrosion resistant stainless steel and aluminum.
Motors - Kiln- and Inverter-duty motors with variable frequency drives.
Installation - In as little as one or two days to ensure minimal kiln downtime.

* Patent Pending

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