According to the company, its DFM and DFME temperature control systems offer built-in mild weather lockout and freeze thermostat, low fire timer delay, and an occupied/unoccupied mode. A new programmable thermostat is included with all systems. The built-in mild weather lockout function is designed to disable the burner when the outside air temperature is at or above the user-defined set point. The freeze thermostat disables the fan if discharge air temperature is not above a user-defined set point after a designated period of time. The low-fire timer delay is said to allow for a delay to high fire during startup, and the occupied/unoccupied mode disables the fan when the set point is decreased by a predetermined number of degrees.