Patented heating elements combined with the Moldatherm fiber insulation and double-walled construction ensure optimum temperature efficiency, fast response, quick heat-up, and rapid cool-down. It features PID temperature control with single-setpoint and programmable control. Advanced engineering and specialized construction techniques include variable density insulation, double shell cabinets, long-life heating elements and vertical, horizontal side swing or swing down doors. Digital overtemperature control on select models protects furnace and load from primary control circuit failure. If high limit is reached, it overrides the main controller and shuts off power to furnace.