Abstract: A thermostat which is configurable to be used with conventional fossil fuel furnaces, electric furnaces, heat pumps and other air conditioning equipment and fans. A setup program is included which requires an installer to enter data specific to the type of HVAC plant installed in the building with the thermostat.

Abstract: A space heating system with a controllable air humidification capability calculates a theoretical value for the temperature of the interior surface of the space's windows. The system controls humidity in the space to a level just below that at which water will condense on the window surfaces.

Abstract: A method and apparatus provide input protection in a system having a controller which monitors a controller terminal for at least one monitor period. The controller terminal is coupled for bi-directional operation. The controller terminal is set to an output configuration for at least a portion of the time that the controller terminal is not being monitored by the controller.

Abstract: An analog to digital converter used along with a variable resistive sensing means utilizes the capabilities of a microprocessor to charge and discharge a capacitor. The time required for this capacitor to discharge is dependent upon the value of the variable resistive sensing means. Circuitry is used to create a pulse whose pulse width is equal to the discharged time of a capacitor through the variable resistive sensing means.

Abstract: A heating system controller is suitable for controlling a heating system based on a plurality of sensed control signals representing control parameters. The heating system controller has a first input suitable for being coupled to provide a control signal. The heating system controller also includes a sensor, coupled to the first input, for sensing control signals at the first input, the control signals having a first pattern, a second pattern, or a third pattern detected over at least two successive time periods. The heating system controller includes a control mechanism, coupled to the sensor for controlling the heating system based on the first, second and third patterns. The control mechanism causes the controller to change modes when the third pattern is sensed.