A Direct Fired Heater (DFH) is Direct fired heaters, or bunk heaters, are devices that can reduce idling by providing in-cabin Heat for drivers in cold temperatures. Some product models offer an engine heating option that will also keep the engine warm overnight. Most DFH"s operate by using fuel directly from the main tractor fuel tank. These devices can generally provide 10 to 20 hours of heat on a single gallon of diesel fuel, depending on the settings and options. Typical costs for this device range from $900 to $3000. For a partial list of manufacturers and device specifications, please visit the SmartWay website at http://www.epa.gov/otaq/smartway/idlingtechnologies.htm.