Abstract: An air exchanger for continuously exchanging indoor air with outdoor air to provide a constant supply of fresh air into a structure which includes a heat exchanger having a continuous structure which defines adjacent first and second sets of channels which open toward opposite sides of the air exchanger. The air exchanger draws outdoor air through the first set of channels in a first direction and indoor air through the second set of channels in a second, counter-direction. Heat is transferred between the indoor and outdoor air streams such that when the outdoor air enters the room, its temperature approaches the indoor temperature and indoor heating or cooling effects are minimized.

Abstract: A portable and compact room air purifier having an internal filter element through which air is drawn by a centrifugal fan and wherein the air is discharged generally uniformly and radially by passing between at least one generally arcuate scroll and a surrounding deflector. The purifier is automatically deactivated in the event of destruction or removal of the filter housing.

Abstract: A pressure switch for an energy recovery ventilator. The energy recovery ventilator for exchanging indoor air with outdoor air. The energy recovery ventilator having a housing including a first, and a second input port, and, a first and a second exhaust port, and a heat exchanger core. The energy recovery ventilator further having a first blower for drawing indoor air into said energy recovery ventilator through said first input port, through said heat exchanger core and out said first exhaust port, and a second blower for drawing outdoor air into said energy recovery ventilator through said second input port, through said heat exchanger core and out said second exhaust port. The pressure switch for determines if there is balanced air flow through the energy recovery ventilator. The pressure switch comprises means for sensing the pressure at the heat exchanger core near all four ports.

Abstract: A latching relay control circuit comprising a latching relay pulse generator circuit and a relay coil drive circuit, the latching relay pulse generator circuit receiving relay control signals and relay reset signals. When a relay control signal changes states, the latching relay pulse generator provides a pulsed signal to the relay and coil drive circuit, the relay and coil drive circuit then changing the state of a latching relay. The relay reset signal is provided during power-up or just before power is lost to the system, the relay reset signal being provided to the latching relay pulse generator circuit wherein the latching relay pulse generator circuit provides a reset signal to the relay and coil driver circuit, and the relay and coil driver circuit opens all of the latching relays it controls.

Abstract: A process which is periodically executed by a programmable thermostat of a heating and cooling system which controls the temperature of a defined space within a structure subjected to a variable external environment. The process advances by an increment of time, .DELTA.t, when the set point temperature of the thermostat changes from an occupied set point temperature to an unoccupied set point temperature. The magnitude of .DELTA.t is a function of the thermal lag of the structure, its external environment, and an amount of temperature change that is acceptable to occupants of the space. Each time the process is executed, the magnitude within predetermined limits of .DELTA.t to be used the next time the process is executed is recalculated.

Abstract: A power supply to supply power to a secondary system. The power supply is adapted to receive power from a plurality of primary systems. The power supply having a first rectifier which supplies power to the secondary system from a first primary system. At least one isolated rectifier which is connected to a primary system other than the first primary system. Wherein the primary system other than the first primary system provides power to the isolated rectifier. A power supply means connected to the first rectifier and the isolated rectifier. Wherein the rectifier and the isolated rectifier provide power to the power supply and the power supply provides power to the secondary system. Wherein due to the characteristic of the isolated rectifier, it is not possible to connect the first primary system out of phase with the primary system other than the first primary system, thereby eliminating unsafe voltages.

Abstract: A ceiling mounted air purifier that provides a high velocity, multi-directional air exhaust pattern that distributes filtered air to all areas of a room which includes a plurality of filters and centrifugal fans. The centrifugal fans are substantially surrounded by baffles which form generally equally spaced exhaust outlets.

Abstract: A thermostat for providing control signals to a variable capacity HVAC system. The thermostat being a setback thermostat with a ramping set point for the recovery period. The thermostat monitoring the load signal required during recovery and increasing or decreasing the ramp slope accordingly.

Abstract: A thermostat which provides a pulse width modulated signal to a gas engine heat pump controller. The thermostat varies the width of the pulse width modulated signal to indicate the load required to heat or cool the room. The thermostat provides an initial idle time for the gas engine heat pump. The thermostat further steps the gas engine heat pump down from high speed operation and idles the engine prior to shutting the engine off.

Abstract: Furnace control for a forced air furnace utilized in multi-zone heating. The forced air furnace is made up of return ducts, a heat exchanger, warm air ducts, a circulation blower, and a burner. The forced air furnace receives heating requests from external control means wherein the furnace provides heat to a zone or multiple zones to be heated. The control for the furnace comprises a temperature sensor for sensing the temperature of the heat exchanger, a regulator for regulating the burner to hold the temperature at the heat exchanger constant during the on cycle of the furnace, a pressure sensor for measuring the pressure in the heat exchanger and a controller for controlling the circulation blower in order to maintain a constant pressure within the heat exchanger.

Abstract: A differential pressure sensor with a compensation means, said differential pressure sensor comprising the diaphragm with a first means having a mass mounted upon the diaphragm. The first means is utilized to determine the position of the diaphragm relative to an initial first position and/or to increase the effective area of the diaphragm. A housing contains the diaphragm, the housing has a first and a second inlet port. The first inlet port provides a first pressure to a first side of the diaphragm and the second inlet provides a second pressure to the second side of the diaphragm, the diaphragm moving to the lesser of the two pressures. A counterweight mechanism is located in the housing having a inner arm and an outer arm. The counterweight mechanism pivots about an axis. The center of gravity of the counterweight mechanism is located on the outer arm.

Abstract: Low cost temperature sensor for thermostats utilizing a calibration resistor and a microprocessor with switchable ports wherein said microprocessor selects between high impedance input or an output for a temperature sensing element and a calibration resistor where by selecting the input, the temperature sensing element or the calibration resistor are effectively removed from the circuit thus allowing the low cost temperature sensor to self calibrate itself.

Abstract: An improved wedgelock assembly for retaining printed wiring boards in a device. The snap-together wedgelock assembly is made up of a screw assembly and a main wedge. The main wedge having fingers for retaining the screw assembly in place.

Abstract: A differential pressure sensor utilizing an opto-reflective sensor comprising a diaphragm with a top and a bottom, the diaphragm having an optical reflector mounted upon it. The diaphragm is mounted in a housing, wherein the housing has a first inlet port and a second inlet port, the first inlet port providing a first pressure to the top of the diaphragm and the second inlet port providing a second pressure to the bottom of the diaphragm. An opto-reflective sensor is mounted in the housing, wherein the opto-reflective sensor provides an optical signal to the optical reflector. The optical reflector reflects the signal back to the opto-reflective sensor, wherein the differential pressure sensor calculates the distance of the optical reflector from the opto-reflective sensor in relation to the relative intensity of the reflected optical signal.

Abstract: An adaptive furnace controller utilizing analog temperature sensing to maintain a constant preselected temperature in the heat exchanger during operation. The adaptive furnace control measuring heat exchanger temperature and regulating a controllable valve to adjust burner firing rate, thereby holding heat exchanger operating temperature constant. Further, creating constant on/off times based on the previous cycle on/off times of the furnace by regulating circulation blower speed. By increasing blower speeds to shorten "on" times or decreasing blower speeds to increase "on" times, and thereby achieving optimum cycle times.

Abstract: A robotic laser soldering apparatus for automated assembly of microscopic components which is capable of acquiring, orienting, and soldering very small electrical components, such as gallium arsenide (GaAs) beam lead diodes, to a circuit board having a soft substrate. The apparatus includes a vacuum pickup means for picking up and holding the diode, pattern recognition means for determining the proper positioning of the diode on the circuit board, and a laser for soldering the diode leads.

Abstract: A low temperature limit for battery powered thermostats for energizing and de-energizing the heating system when the battery can no longer operate the thermostat. The thermostat comprises a battery powered thermostat control for energizing and de-energizing the heating system and a low temperature limit electrically connected in parallel with the battery powered thermostat control. The battery powered thermostat control disables a controllable switch and, thereby, the low temperature limit bimetal switch when the battery is charged. When the battery is discharged, it enables the low temperature bimetal switch limit. Thereby, when the thermostat is no longer operational, the low temperature limit energizes the heating system when the ambient temperature present on the thermostat is below a preselected temperature.

Abstract: An apparatus to match initiation of temperature changeover settings of a thermostat to a duty cycle of an air temperature conditioning plant without degrading the comfort level of the area of temperature modification. The apparatus prevents short-cycling of either a heating or a cooling system which can occur due to changes in the setpoint temperature. The apparatus operates by determining the length of time of "on" portion and"off" portion of the duty cycle of the air temperature conditioning plant. It then determines the time until the upcoming cycle of the temperature conditioning plant and either advances or delays the temperature changeover until the beginning of the upcoming "on" period or the upcoming "off" period of the upcoming duty cycle, or the last "on" period or the last "off" period of the last duty cycle of the air temperature conditioning plant.

Abstract: An improved wedgelock assembly for retaining printed wiring boards in a device. The snap-together wedgelock assembly is made up of a screw assembly and a main wedge. The main wedge having fingers for retaining the screw assembly in place.