Abstract: An electronic thermostat having high and low voltage control capability and varied functional capabilities. The thermostat is particularly suited for use with fan coil heating and cooling units. Specifically the thermostat uses relays to actuate external devices such as heating and cooling equipment, fans and dampers. The use of relays permits control voltages for these external devices to be different (e.g. 24 VAC, 208-230 VAC or 277 VAC).

Abstract: A controller implemented in a heating, ventilation and air-conditioning (HVAC) distribution system provides improved control by implementing a general regression neural network to generate a control signal based on identified characteristics of components utilized within the HVAC system. The general regression neural network utilizes past characteristics and desired (calculated) characteristics to generate an output control signal. The general regression neural network is implemented in a feedforward process, which is combined with a feedback process to generate an improved control signal to control components within the HVAC distribution system. Implementation of the general regression neural network is simple and accurate, requires no input from an operator supervising the controller, and provides adaptive, real-time control of components within the HVAC distribution system.

Abstract: A global control system is implemented in a heating, ventilation and air-conditioning (HVAC) distribution system. The system allows local controllers and a source controller to exchange data between one another so that optimization of control for a local component is not sacrificed for optimization of control for a source component, and vice versa. The controllers have their control process sudivided into an identification process and a control process. The identification process periodically identifies characteristics related to the component to be controlled. The control process continuously generates a control signal to be applied to the component to control the component. The control process is further subdivided into a feedforward process and a feedback process. The feedforward process utilizes the identified characteristics to generate a control signal based on calculated system variables, while the feedback generates a control signal based on measured system variables.

Abstract: A system for monitoring the operation of laboratory fume hoods includes a local area network for transferring data representing alarm conditions, and other special functions, to a building supervisory control system. The system has a calibrating capability which is adapted to build a database of the operating parameters of the fume hood which can be used to detect any degradation of the operation of the fume hood.

Abstract: A controller controls a prime mover (source component) in a heating, ventilation and air-conditioning (HVAC) distribution system. The controller determines a static pressure setpoint for the source component by first determining the pressure loss of each branch throughout the system. The controller then determines the pressure loss contributed by local components located within each branch of the system. The maximum of the branch pressure losses and the maximum of the component pressure losses are summed to provide the static pressure setpoint for the source component. The method provides control of the prime mover independent of the configuration of the system.

Abstract: A building automation system is disclosed which enables reliable operation and cost effective expansion. The system utilizes pairs of complementary modules, one of which is a primary module that is installed at a main cabinet and the other is an expansion module that can be located adjacent the mechanical systems which are to be monitored and controlled. Through the use of the complementary pairs of modules, the necessity for providing home runs of power conductors from the mechanical system to the main cabinet are substantially reduced if not eliminated, which greatly reduces the costs of materials and labor in a total installation.

Abstract: A fume hood exhaust terminal for monitoring and controlling gas flow in a duct system includes a tubular duct segment having an upstream end, a downstream end, and an inner periphery, as well as an annular ring secured to the inner periphery between the upstream and downstream ends. A differential pressure transmitter device is disposed on the duct segment for measuring the pressure differential across the ring and for generating a corresponding flow signal. A damper is disposed in the duct segment between the differential pressure measuring device and the downstream end, and an actuator is located on the duct segment to be responsive to the signal generated by the differential pressure transmitter device and connected to the damper for selectively controlling the position of the damper in the duct segment to maintain a specified gas flow.

Abstract: A fume hood controller and method which compensates for resistance to air flow through a by-pass opening that exists due to a grille or louvre overlying the by-pass opening.

Abstract: A three-way valve having a valve body with an internal output chamber. A supply means is in fluid communication with the output chamber for providing a source of fluid to pressurize the output chamber and thereby obtain a desired device output signal. An exhaust means in fluid communication with the output chamber provides a passage for the fluid to vent from the output chamber out to atmosphere. An output means, also in fluid communication with the output chamber, is included for directing the device output signal from the output chamber to a pneumatic device. A single bending element selectively actuates the supply means or the exhaust means to obtain a predetermined pressure value to be maintained by the valve. The bending element is positioned adjacent and between the supply and exhaust means.

Abstract: A system for monitoring the operation of laboratory fume hoods is disclosed. The system includes a local area network for reporting alarm conditions and other data to a building supervisory control system. The system has a calibrating capability which is adapted to build a database of the operating parameters of the fume hood which can be used to detect any degradation of the operation of the fume hood.

Abstract: A dual-duct HVAC system for providing a desired comfort level in a room, includes a controller that carries out a simple operation that determines the total open damper positions for dual dampers in a dual duct system to effect a desired air flow. Using the total open damper position information as damper control information, the controller also determines a relative damper position difference required between the two dampers to effect a desired temperature level while also meeting the air flow requirement as determined from the total open damper position information. The combination of the total open damper position information and the relative damper position difference is used as control information to control both dampers. Preferably, the controller gives priority of air flow control over temperature control by determining a valid damper position difference range for use in conjunction with the total open damper position information.

Abstract: Apparatus for use in determining the position of an object such as a sash door of a laboratory fume hood which has an elongated base member for attachment to the fume hood adjacent the sash doors. It includes an electrical switching means having an elongated electrical resistance means that provides a signal indicative of the position of a sash door, and an actuator means associated with each sash door adapted to move when the sash door is moved. The actuator means includes an actuator assembly positioned to operate the switching means at a switch location that varies as the sash door is moved. The actuator means includes a linkage means that permits accurate operation even though there is undesirable movement of the door relative to the base member.

Abstract: A controller for unit ventilators which include processing means having associated memory that enables control schemes to be used. The controller is modular and compact in its construction, is easily installed in existing unit ventilators and provides not only the controlled pneumatic pressure in the output lines for the controller, but also provides electrical control signals for controlling the operation of the fan. The controller is adapted to control unit ventilators having auxiliary radiation and is also adapted to control ASHRAE cycle 3 type installations.

Abstract: An apparatus for mounting a device for determining the position of a sliding sash door in a laboratory fume hood in the track of the sash door. This apparatus securely and permanently mounts the sensing means in the track even after exposure to corrosive and noxious chemicals such as MEK. This apparatus is thin enough to not to interfere with the operation of the sash door yet rigid enough to protect the sensing means. The apparatus includes a PVC base having a generally "I" shaped cross section with two recesses formed by two end portions and a middle portion of the base. The sensing means is located in one of these recesses and is secured therein by a first adhesive means. The PVC base and sensing means are attached to the track of the fume hood by a second adhesive means located in the other recess in the base. Both adhesive means are comprised of a high performance acrylic adhesive which is splash resistant to MEK.

Abstract: An electro-pneumatic pressure transducer is provided with a valve body assembly having a supply chamber, an exhaust chamber and an intake assembly to provide a source of fluid to the transducer. The transducer also has an output assembly directing the fluid to a pneumatic actuator. The valve body further includes a supply valve assembly and an exhaust valve assembly having bender elements adjustably mounted to the valve body with respect to nozzles. A manifold structure is included for fluidly connecting the supply valve, the exhaust valve and the output assemblies. A pressure sensor is used to measure the pressure in the valve body and is responsive to increases or decreases of the pneumatic pressure in the valve body. A monitor is used to monitor the power source and to generate a failure mode signal when the power source fails to supply a predetermined level of power.

Abstract: A controller having two cascaded PID control loops in the control of unit ventilators of the type which have a heating coil, a fan, and a damper for admitting outside air into a room in which the unit ventilator is located. The controller utilizes the sensed room temperature and a room temperature set point to generate a set point for the temperature of the air being discharged from the unit ventilator, and utilizes the discharge temperature set point and the sensed discharge temperature to control the damper position and the operation of the heating coils of the unit ventilator.

Abstract: An output pressure control apparatus particularly adapted for HVAC control applications, and being of the general type which admits a higher supply pressure to a controlled output line when it is desired to increase the pressure in the output line and which bleeds pressure from the controlled output line when it is desired to reduce the pneumatic output pressure. The pressure regulating apparatus requires only a single filter means and utilizes bidirectional flow of air through the filter means during normal operation which cleans the filter means.

Abstract: Fume hood controller apparatus includes a computing means, together with associated memory, which can be configured for horizontally and/or vertically moveable sash doors by inputting the necessary dimensions of the sash doors and other structural features, such as the upper lip height, frame widths and the like. The apparatus rapidly calculates the size of the uncovered area of the fume hood as a functions of the position of the sash doors.