Abstract: A control for an air treatment unit, such as a space heater having a heat source and an air handler that draws air from outside the space and from within the space in order to form a combined stream of air that is discharged to the space. The control includes a temperature setpoint control adapted to controlling the heating source in order regulate air temperature in the space to a particular air temperature setpoint and a temperature setpoint setback control that is adapted to decreasing the air temperature setpoint to a lower temperature setpoint during periods when it is anticipated that the space will be unoccupied. A differential pressure sensor senses a pressure differential between the space and outside of the space. A pressure control is responsive to the pressure sensor in order to control the proportion of air drawn from outside the space to air drawn from within the space.

Abstract: The present invention relates to transforming a pre-existing heating installation comprising a main heat generator such as a boiler which is associated with a modulating mixer valve controlled by a P or PD type regulator which is responsive to outside temperature and to the departure temperature of the heating water.

Abstract: A duty cycle controller for an air conditioning system. Solid state switches are connected in series with the heating and cooling switches of a thermostat in circuits for energizing the cooling and heating subsystems, respectively, of an air conditioner. A switch control circuit, when enabled, causes the solid state switches to be conductive when set and nonconductive when reset. Timing signals from a counter applied to the switch control circuit determine the state of the switch control circuit and thus the duty cycles for the heating and cooling subsystem. The controller is provided with a safety circuit which disables the switch control circuit to render the solid state switches nonconductive for a predetermined period of time after a power interruption or after a cooling or heating switch of the thermostat opens. The controller assures that each heating and cooling duty cycle begins with a full energization period. The length of the heating and cooling duty cycles can be readily varied.

Abstract: A multi-functional sensing and measuring system capable of detecting both temperature and humidity is fabricated from a porous metal-oxide ceramic whose dielectric constant varies with temperature and whose electric resistance varies with ambient humidity. The sensing element is connected in series with a resistor and a rectangular pulse voltage is applied across the series combination, and the ambient temperature and humidity are measured simultaneously in terms of (i) the circuit time constant (to measure temperature) of a transient state value and (ii) the steady state value of the voltage across the resistor (to measure humidity).

Abstract: A temperature controlled timer useful for controlling the application of power to apparatus such as automobile block heaters or the like. In one embodiment the time of application of power prior to a shut off time is decreased with increasing ambient temperature. In another embodiment the duty cycle of cyclically applied power is changed so that the power on period becomes shorter and the power off period becomes longer with increasing ambient temperature. Significant conservation of power results.

Abstract: The invention provides a system for transmitting operational command signals to one or more remote unit ventilator units from a master control panel. A number of selected command signals corresponding to operational modes such as occupied day, night setback, morning ready and load shedding modes may be transmitted over a two-wire electrical transmission line to which the remote units are parallelly connected. The remote units receive and respond to the command signals by initiating the commanded mode.