Abstract: A wall plate for a wall thermostat blocks intrusion air from the thermostat. The wall plate has a wire passage aligned with the wall penetration through which the thermostat wires emerge. The wall plate member directs any intrusion air that flows out the penetration away from the cavity of said thermostat. An insulating layer, e.g., a closed-cell foam sheet, in the wall plate insulates the thermostat from direct thermal contact with the wall. The closed-cell material closes around the thermostat wires. Bosses or feet on the thermostat back plate create a standoff between the wall plate and the thermostat.

Abstract: A programmable thermostat can be programmed and configured using a set up selector keys or pushbuttons to enter set up modes and to move from screen to screen on the thermostat display, and using up and down selector keys to change the time and temperature settings within each screen or mode. The thermostat can be set into a master mode be depressing two of the selector keys simultaneously, and then the programmed settings of the thermostat can be electronically transferred to each of a batch of similar thermostats using a thermostat conductor in a multi-conductor thermostat wire such as the fan conductor. The thermostat can be toggled back to a normal or target mode for thermostat operation.

Abstract: A plug or grommet fits into the opening in the back plate of a thermostat and blocks or diverts intrusion air from entering the interior of the thermostat housing from the wall penetration for the thermostat wires. The thermostat wires are fed through the grommet, which is a soft rubbery material that closes over the wires and blocks the intrusion air. Alternatively, a wall plate can be used between the back plate of the thermostat and the wall where the thermostat is mounted.

Abstract: A plug or grommet fits into the opening in the back plate of a thermostat and blocks or diverts intrusion air from entering the interior of the thermostat housing from the wall penetration for the thermostat wires. The thermostat wires are fed through the grommet, which is a soft rubbery material that closes over the wires and blocks the intrusion air. Alternatively, a wall plate can be used between the back plate of the thermostat and the wall where the thermostat is mounted.

Abstract: An actuation circuit for an electromechanical relay employs a microprocessor and a switching transistor to actuate a relay over a wide range of applied voltages. The switching transistor is connected in series with the actuator coil. A voltage sensing circuit is connected to one input of the microprocessor, which produces a pulse-width modulated actuator output to gate the switching transistor. The microprocessor is suitably programmed so as to produce a pulse width modulated signal actuator signal whose duty cycle is a function of applied voltage. The RMS current through the relay coil is sufficient to ensure good actuation, but does not overstress the coil. The relay is selected to have its rated actuation voltage at or below a lower end of the expected range of applied voltages. A relay actuation boost arrangement can include a transistor or an SUS (silicon unidirectional switch) or similar negative resistance device.

Abstract: Arrangement for dc signaling between a transmitter or transceiver over a single pair of conductors to another transceiver or receiver of similar design. The conductors carry a dc communications voltage at a level V.sub.comm (e.g., 24 to 35 volts dc) and power for the tranceivers, receivers and/or transmitters of the system. The transceiver comprises a microprocessor having a signal input terminal V.sub.in, a signal output terminal V.sub.out, a sensor input circuit coupled to a sensor transducer, e.g., a temperature sensor, and a control output circuit coupled to control an external device, e.g., a furnace relay. A voltage limiting circuit device coupled to the pair of conductors supplies the microprocessor with a supply voltage V.sub.dd at a predetermined level (e.g., 5 volts dc) less than the communications voltage level V.sub.comm.

Abstract: A start circuit for a single phase AC induction motor employs a triac or similar device in series with the motor start or auxiliary winding. The triac device has associated circuitry so that it turns on in response to an increase in the time rate of change of applied voltage. In one version a PNP transistor and a capacitive timing circuit are employed to cut in the start winding. In another version a second, pilot triac is employed.