Abstract: A method and apparatus for protecting humidity sensing equipment within an enclosure that can be mounted in the return airflow of a furnace duct. The humidity sensing equipment is mounted on a printed wiring board, which is protected between a mounting base and an operational cover. The mounting base includes a protective shield which allows the humidity sensing equipment to protrude into the furnace duct and prevents damage to the humidity sensing equipment during installation.

Abstract: A spring return rotary actuator incorporating a DC brush commutated electric motor and a pulse width modulation drive circuit which reduces the voltage at which current is supplied to the motor once a rotation sensor senses that the actuator output shaft has stalled. The drive circuit also includes a temperature responsive feature which increases the voltage at which current is supplied to the motor in the event a sensed temperature exceeds a temperature limit.

Abstract: An apparatus and method for determining and communicating a need for water heater clean out based on scale deposit buildup is disclosed in which a sensed increase in average reheat time is employed as a measure of deposit buildup and to initiate a clean out alert.

Abstract: An environmental control system for a building intended for human occupancy in which the operating environment is controlled in response to any of a plurality of states of the building as represented by a state vector. A plurality of independently operating controllers contain stored sets of addressable control functions which are accessed by the state vector signal. The controllers produce operating point signals for apparatuses which affect operating environment parameters in accordance with the addressed control functions.

Abstract: A gas flow control valve configured to facilitate back-to-back mounting with a second, similarly constructed valve. The gas valve includes a valve body defining an inlet port and an outlet port, the inlet and outlet ports being surrounded by seal forming O-rings of different diameters. Flanges surrounding the inlet and outlet ports are configured with distinct attachment features for accommodating bolts for securing one valve in series with another or with a pipe flange or other auxiliary device, the inlet flange having either a slot dimensioned to hold and prevent rotation of a bolt head or nut, or a clearance slot permitting use of a wrench, and the outlet flange having the other slot configuration.

Abstract: A humidity control system for an enclosure requiring heat from a furnace and having one or more windows, includes sensors for the enclosure temperature and humidity, and a means for measuring the percentage of time which the furnace is operating (load factor). The system estimates the interior window temperature based on these parameters and controls humidity added to the enclosure air to prevent the enclosure air dew point temperature from rising above the estimated window temperature. This prevents condensation on the window surfaces. The estimation can be adjusted to compensate for different insulation characteristics of the window. In a preferred embodiment, the enclosure air temperature and humidity are derived from sensors conveniently located in the return air duct.

Abstract: A controller for a system has two or more operating modes. The controller operates according to a different control algorithm in each operating mode. A manually operable switch typically used for sending a reset signal to the controller, may also be used to change operating modes. The controller changes operating mode when it detects that the switch is manually operated during a preselected phase of controller operation, typically when power is first applied. The disclosed embodiment allows up to four different operating modes to be selected. A first selection of operating modes can occurs if the switch is held closed during startup and then immediately released. A second selection of operating mode occurs if the switch is pressed within a preselected time interval after power is first applied to the controller. Both selections can be made during a single start-up event.

Abstract: A convertible two-mode pressure regulator in which a main valve regulates fluid flow between an inlet and an outlet in response to a control pressure produced by a mechanically operated regulator valve, the control pressure depending on the outlet pressure and the force applied by a compression spring to a diaphragm carrying a regulator valve closure element. Compression of the regulator spring is controlled by a mechanical lever assembly and a shaft assembly which is selectively positionable by a selector knob to obtain higher or lower regulator spring force. Adjustable stops provide for individual adjustment of low and high outlet pressures for each of two pressure ranges.

Abstract: An enhanced controller for an air conditioning system incorporating mechanical cooling equipment and an economizer, the enhanced controller including circuits for producing signals indicative of commanded changes in temperature of air admitted into the air conditioned space and of a non-temperature parameter, such as carbon dioxide concentration, of air within the space. The signals are supplied to a logic circuit which produces a ventilation damper control signal based on which of the temperature and non-temperature parameters requires greater change. Freeze protection, and maximum and minimum damper position circuits override the basic damper control signal to avoid excessively low space temperatures and to provide air exchange limits.

Abstract: A load transfer device for use with tandem mounted actuators. The load transfer device includes an actuator coupling assembly and a ground connection assembly. The actuator coupling assembly connects the first actuator to the second actuator and includes a movement apparatus. The movement apparatus is configured to allow the housing of the first actuator to move relative to the housing of the second actuator. The ground connection assembly is associated with the actuator coupling assembly and movably connects the first and second actuators to a rigid support structure. During a load transfer operation, the actuator coupling assembly transfers an unequal load from the first actuator to the second actuator. In particular, the movement apparatus allows the first actuator to move relative to the second actuator. Further, the actuator coupling assembly is configured to transpose movement of the first actuator into a forced, reciprocal movement of the second actuator.

Abstract: A solid-state fail safe gas valve system in which first and second gas valves are arranged in series in a gas passageway, the valves being actuatable by first and second solenoid operators respectively, the second operator requiring a voltage greater than the operating voltage supplied to the valve system to achieve actuation. The operators are separately energized through microprocessor controlled switches so that a capacitor connected across the second operator and its switch is pumped to a voltage above the supplied voltage by voltage induced by interrupted energization of the first operator.

Abstract: A diaphragm valve including structure which incorporates a support surface positioned to limit extension away from a main valve seat of a valve seat closure diaphragm. Alternative embodiments have the support surface formed on an insert within the valve housing, and formed as part of the interior surface of a wall of the housing. Alternatives for conveying control pressure to the side of the seat closure diaphragm adjacent the support surface include forming the surface on a body of porous material, and forming the surface with a channel which communicates with a relief port. Inclusion of a support surface minimizes stress and strain in the closure diaphragm when the valve is in an open state, thereby increasing the allowable valve working pressure.

Abstract: A multi-way valve unit which provides low pressure unregulated gas flow and high pressure regulated gas flow in an integrated gas control system. A main and bypass diaphragm valves control gas flow through the gas valve system, the main and bypass valves being opened by pressure differentials on their respective valve diaphragms. A regulator valve and a snap valve modify gas pressure applied to the main and bypass valves diaphragms respectively. A control means actuates the regulator and snap valves based on degree of temperature deficiency sensed in a monitored space. The control means opens the snap valve to provide unregulated gas flow when low gas pressure is required, and opens the regulator valve to provide regulated high flow when high gas pressure is required.

Abstract: A power stealing circuit provides operating power for a environmental control such as a thermostatic control while controlling the current in a power supply line to a load in response to the cycling output of the environmental control. A pair of power FETs are connected to the series power terminals, and the gates are controlled by logic and phase timers. FETs are turned off at the end of a phase, while a small amount of power sufficient to operate the control and circuitry is diverted to a power storage circuit, then the FETs are turned back without substantial interruption to the load. A preferred embodiment uses a bi-directional charge pump to transfer power between low- and high-voltage power storage circuits. The circuit can operate with symmetrical or nonsymetrical AC or DC loads.