Abstract: A control algorithm for controlling an economizer circuit in a chiller system is provided. The control algorithm opens and closes a port valve in the economizer circuit in response to predetermined criteria to engage and disengage the economizer circuit. The predetermined criteria can include an operating parameter of a compressor and a level of liquid refrigerant in a flash tank.

Abstract: A single medium voltage starter box is mounted on a chiller unit with the other components of the chiller system. The starter box can be positioned on the chiller system unit to permit the starter box to be close coupled to the motor, and specifically to the main motor lead exit hub without the need for any power conduit connections between the starter box and the motor. In addition, the starter box also does not require any control interface and receives controls from a control panel. A short conduit connection between the control panel and the starter box is used to provide the necessary connections between the control panel and the starter box.

Abstract: A system is provided for attenuating noise in at least two positive displacement compressors proximately located from each other for use with at least one heating or cooling system. A lead compressor and a lag compressor have a selectably controllable rotational speed and a selectably controllable phase of operation. A controller selectably controls the rotational speed and the phase of operation of each of the compressors. The controller controls the rotational speed of the compressors at a predetermined rotational speed that is substantially the same for each of the compressors. The controller controls the phase of operation of the compressors by shifting the phase of operation of the lag compressor so that an outlet pressure pulse operatively produced by the lag compressor is substantially evenly spaced between successive outlet pressure pulses operatively produced by the reference compressor.

Abstract: An evaporator including a shell having a first end and a second end. A plurality of tubes are disposed within the shell to circulate refrigerant through the shell. A plurality of shell inlets are in fluid communication with the shell to deliver a fluid to exchange heat in the plurality of tubes, preferably through a baffle arrangement. At least one of the shell inlets may be arranged to deliver fluid to the shell adjacent to the first end. In addition, at least one of the other shell inlets may be arranged to deliver fluid adjacent to the second end. A shell outlet is in fluid communication with the shell to discharge fluid from the shell. The shell outlet is arranged to receive the combined liquid delivered to the shell by the plurality of shell inlets.

Abstract: A stability control algorithm is provided for a centrifugal compressor. The stability control algorithm is used to control a variable geometry diffuser and a hot gas bypass valve (when provided) in response to the detection of compressor instabilities. The stability control algorithm can adjust the position of a diffuser ring in the variable geometry diffuser in response to the detection of a surge condition or a stall condition. In addition, the diffuser ring in the variable geometry diffuser can be adjusted to determine an optimal position of the diffuser ring. The stability control algorithm can also be used to open a hot gas bypass valve in response to the detection of continued surge conditions.

Abstract: A control algorithm for controlling an economizer circuit in a chiller system is provided. The control algorithm opens and closes a port valve in the economizer circuit in response to predetermined criteria to engage and disengage the economizer circuit. The predetermined criteria can include an operating parameter of a compressor and a level of liquid refrigerant in a flash tank.

Abstract: A single medium voltage starter box is mounted on a chiller unit with the other components of the chiller system. The starter box can be positioned on the chiller system unit to permit the starter box to be close coupled to the motor, and specifically to the main motor lead exit hub without the need for any power conduit connections between the starter box and the motor. In addition, the starter box also does not require any control interface and receives controls from a control panel. A short conduit connection between the control panel and the starter box is used to provide the necessary connections between the control panel and the starter box.

Abstract: A control system for a steam turbine driven chiller unit is provided. The control system automatically utilizes the full range of the governor, compressor pre-rotation vanes, and hot gas bypass valve capabilities to control the capacity of the chiller and provide anti-surge and override control functions to prevent undesirable operational ranges while maintaining maximum efficiency of operation.

Abstract: A method for repairing an HVAC system is disclosed. The method includes monitoring a plurality of sensors positioned throughout the HVAC system and receiving data associated therewith, determining whether the data received from the plurality of sensors is within corresponding predetermined operational parameters, analyzing data determined to be outside the corresponding predetermined operational parameters to diagnose a malfunction of the HVAC system, accessing an on-board bill of materials to determine a proper replacement part to correct the malfunction, automatically ordering the replacement part, and automatically dispatching a service technician to install the replacement part.

Abstract: A method for repairing an HVAC system is disclosed. The method includes monitoring a plurality of sensors positioned throughout the HVAC system and receiving data associated therewith, determining whether the data received from the plurality of sensors is within corresponding predetermined operational parameters, analyzing data determined to be outside the corresponding predetermined operational parameters to diagnose a malfunction of the HVAC system, accessing an on-board bill of materials to determine a proper replacement part to correct the malfunction, automatically ordering the replacement part, and automatically dispatching a service technician to install the replacement part.

Abstract: A structural member is provided for constructing a door. The structural member includes a first end portion, a second end portion disposed opposite the first end portion and a web disposed between the first end portion and the second end portion. A channel is disposed between the web and the second end portion, the first end portion being configured to receive a portion of a first door panel to permit the first door panel to be connected to the structural member. The second end portion is configured to receive a portion of a second door panel to permit the second door panel to be connected to the structural member. The channel is configured to receive a peripheral portion of the second door panel, the first and second door panels to be connected to the first and second end portions without mechanical fasteners.

Abstract: A system for defrosting an air-to-air heat pump system is disclosed. A bypass loop transfers refrigerant at a higher temperature and pressure than is normally cycled through the outdoor unit to an outdoor coil to defrost ice on the outdoor coil. The bypass loop includes a valve movable between closed and open positions. A sensor monitors a preselected condition indicative of outdoor coil performance. A controller communicates with the valve and the sensor. Once the controller determines that a preselected set point of a preselected condition indicative of deteriorating performance has been reached, the controller sends a signal to open the valve, allowing warm refrigerant to bypass expansion valves and flow to the outdoor unit to defrost the outdoor unit. Once defrosting is accomplished, the valve can be moved to a closed position to resume normal operation of the heat pump unit.

Abstract: A method for repairing an HVAC system is disclosed. The method includes monitoring a plurality of sensors positioned throughout the HVAC system and receiving data associated therewith, determining whether the data received from the plurality of sensors is within corresponding predetermined operational parameters, analyzing data determined to be outside the corresponding predetermined operational parameters to diagnose a malfunction of the HVAC system, accessing an on-board bill of materials to determine a proper replacement part to correct the malfunction, automatically ordering the replacement part, and automatically dispatching a service technician to install the replacement part.

Abstract: An apparatus and method for a panel construction for an air-handling unit includes at least one base member having a top surface and a bottom surface opposite the top surface and a skin having opposed surfaces. An insulator having opposed surfaces is disposed between the top surface of the at least one base member and the skin, one surface of the insulator being securely connected to the top surface of the at least one base member and the other surface of the insulator being securely connected to one surface of the skin. The secure connections between the opposed surfaces of the insulator and the top surface of the at least one base member and one surface of the skin substantially preventing a continuous path of substantially reduced thermal insulative properties between the at least one base member and the skin.

Abstract: An apparatus and method for a panel construction for an air handling unit includes a first skin and a second skin. A plurality of members is disposed between the first and second skin to separate the first and second skin. Each member of the plurality of members is connectable to one or both the first and second skins and includes at least one structural member and at least one thermal break. The at least one structural member and the at least one thermal break are configured and disposed to prevent a continuous path of substantially reduced thermal insulative properties between the first and second skin.

Abstract: A dished head header assembly for a heat exchanger having a containment body that includes a rounded, or dished, wall portion forming an interior cavity. A flange attaches to the containment body and fastens the header assembly to the heat exchanger. A plurality of refrigerant passageways are extended through an opening in the containment body into the interior cavity. At least one baffle is attached to the rounded wall portion. The baffle divides the interior cavity into a plurality of sub-cavities. At least one divider divides the sub-cavities into a plurality of chambers. The plurality of passageways includes an inlet connection and an outlet connection for a plurality of refrigerant circuits. Each passageway is disposed in a corresponding chamber of the plurality of chambers. Extensions into the headers with diffusers insure efficient operation and performance of the heat exchanger. The adjustable flow restrictor plate maintains optimum velocities to further enhance performance.

Abstract: A variable speed drive with a boost converter is provided for a chiller system driven by a switched reluctance motor. The boost converter can be a diode or thyristor rectifier followed by a boost DC/DC converter or a three-phase pulse width modulated boost converter. The boost converter provides a boosted voltage to the DC link, which results in a boosted voltage being applied to the switched reluctance motor by the inverter of the variable speed drive.