Abstract: A method of controlling an HVAC circuit, comprises allowing refrigerant to circulate within the HVAC circuit, wherein the HVAC circuit comprises an evaporator coil, a condenser coil, at least one fan configured to provide airflow to the condenser coil, at least one expansion valve, and at least one compressor. The method continues by receiving a temperature measurement and determining based on the temperature measurement, a minimum fan speed configured to avoid pressure spikes within the condenser coil. The method concludes by sending a signal to the at the least one fan to direct the at least one fan to spin at a rate greater than or equal to the minimum fan speed when the measured temperature is less than a predetermined temperature, wherein, when the refrigerant circulates through the condenser coil, the minimum fan speed is greater than zero rotations per minute.

Abstract: According to certain embodiments, a system comprises a controller and an HVAC system with components comprising an evaporator unit comprising an evaporator coil, an indoor fan, and a discharge air duct and a condenser unit comprising a compressor, a condenser coil, and an outdoor fan. The system is configured to determine that a first or a second level of evaporator coil freeze risk is present and to communicate an instruction to the HVAC system with a first or a second action to counteract the freeze risk. For example, in certain embodiments, the actions comprise changing the indoor fan speed, changing the compressor speed, and changing the outdoor fan speed.

Abstract: A system and method are described that help to alleviate pressure and strain spikes in and around dead tubes or frontiers between stages in a multi-stage condenser coil. Instead of cycling a fan off and on, fans associated with the condenser are kept running at a low speed instead of being turned off. Preventing the fans from turning off completely helps to even out the pressure and strain spikes. The present teachings can be especially beneficial in aluminum-based coils. The present teachings include both a unit controller that carries out the teachings, and a system based on temperature and/or pressure switches connected to a fan controller.

Abstract: A system based on temperature and/or pressure switches connected to a fan controller. An HVAC circuit includes at least one condenser coil with a plurality of tubes, one or more stages coupled to one or more compressors, at least one temperature sensor, at least one fan configured to provide airflow across the plurality of tubes, and a controller. Instead of cycling the fan off and on, fans associated with the condenser are kept running at a low speed.

Abstract: According to certain embodiments, a system comprises a controller and an HVAC system with components comprising an evaporator unit comprising an evaporator coil, an indoor fan, and a discharge air duct and a condenser unit comprising a compressor, a condenser coil, and an outdoor fan. The system is configured to determine that a first or a second level of evaporator coil freeze risk is present and to communicate an instruction to the HVAC system with a first or a second action to counteract the freeze risk. For example, in certain embodiments, the actions comprise changing the indoor fan speed, changing the compressor speed, and changing the outdoor fan speed.

Abstract: A system and method are described that help to alleviate pressure and strain spikes in and around dead tubes or frontiers between stages in a multi-stage condenser coil. Instead of cycling a fan off and on, fans associated with the condenser are kept running at a low speed instead of being turned off. Preventing the fans from turning off completely helps to even out the pressure and strain spikes. The present teachings can be especially beneficial in aluminum-based coils. The present teachings include both a unit controller that carries out the teachings, and a system based on temperature and/or pressure switches connected to a fan controller.

Abstract: A compressor assembly including a housing that encloses a sealed interior volume and defines an inlet opening and an outlet opening. Refrigerant is communicated from a suction line into the interior volume through the inlet opening. Refrigerant is communicated from the interior volume to a discharge line through the outlet opening. A first compressor mechanism is disposed within the interior volume and is adapted to compress the refrigerant. A first fitting is mounted on an exterior surface of the housing and is in communication with one of the inlet and outlet openings. The first fitting defines a first passageway for communicating the refrigerant between the one opening and a respective one of the suction and discharge refrigerant lines. The fitting further defines a first duct in communication with the first passageway. A first pressure relief valve is mounted in communication with the first duct.

Abstract: A terminal assembly for a hermetic compressor including a metallic disk having an interior side, an opposite exterior side, and a plurality of holes extending therethrough, the interior side of the metallic disk defining a first diameter sized to fit within an aperture of a compressor housing, the metallic disk defining a second diameter adjacent the first diameter and sized larger than the first diameter; and a plurality of terminal pin assemblies, each one of the terminal pin assemblies received in a corresponding one of the plurality of holes. Each of the terminal pin assemblies include an elongate conductive pin; and an annular collar disposed about the conductive pin and having a threaded outer surface, wherein the threaded outer surface threadedly-engages a corresponding one of the threaded holes.

Abstract: A water heating system including a water storage vessel; a water circuit; first and second heat exchangers operably disposed in the water circuit; and a vapor compression system defining a refrigerant circuit. The vapor compression system includes first and second compressor mechanisms. The first compressor mechanism compresses the refrigerant from suction pressure to intermediate pressure. The second compressor mechanism compresses the refrigerant from the intermediate pressure to a supercritical discharge pressure. The first heat exchanger is operably disposed in the refrigerant circuit between the first and second compressor mechanisms, and exchanges heat between intermediate pressure refrigerant and water. An expansion device is operably disposed in the refrigerant circuit. An evaporator is operably disposed in the refrigerant circuit between expansion device and first compressor mechanism.

Abstract: A vapor compression system including a refrigerant circuit having operably coupled thereto, in serial order, a compressor, a first heat exchanger, an expansion device, and a second heat exchanger. A valve is disposed within refrigerant circuit between first heat exchanger and expansion device, and has a first position and a second position. A defrost circuit having operably coupled thereto a third heat exchanger defines an inlet in fluid communication with refrigerant circuit through valve when valve is in second position, and an outlet disposed in refrigerant circuit between inlet and expansion device. A check valve is disposed in defrost circuit between third heat exchanger and outlet. The check valve allows refrigerant to return to refrigerant circuit through outlet and prevents refrigerant from entering third heat exchanger via outlet. The refrigerant flows through third heat exchanger and second heat exchanger when valve is in second position.

Abstract: A terminal assembly for a hermetic compressor including a metallic disk having an interior side, an opposite exterior side, and a plurality of holes extending therethrough, the interior side of the metallic disk defining a first diameter sized to fit within an aperture of a compressor housing, the metallic disk defining a second diameter adjacent the first diameter and sized larger than the first diameter; and a plurality of terminal pin assemblies, each one of the terminal pin assemblies received in a corresponding one of the plurality of holes. Each of the terminal pin assemblies include an elongate conductive pin; and an annular collar disposed about the conductive pin and having a threaded outer surface, wherein the threaded outer surface threadedly-engages a corresponding one of the threaded holes.

Abstract: A twin cylinder rotary compressor including first and second cylinders; a crankshaft having first and second eccentrics mounted thereon, the first eccentric disposed within the first cylinder, the second eccentric disposed within the second cylinder; and a separator plate disposed between the first and second cylinders and having a first piece and a complementary second piece. Each of the first and second pieces includes an interior surface defining a semi-circular recess. The interior surface and the semi-circular recess of the second piece is complementary to the interior surface and the semicircular recess of the first piece, respectively, such that the semi-circular recesses combine to form a circular bore, which closely captures a portion of the crankshaft located between the first and second eccentrics.

Abstract: A hermetic compressor assembly that includes a hermetically sealed housing. A motor and compressor mechanism are disposed within the housing. The housing wall includes an aperture and a terminal block is mounted on the housing wall proximate the aperature. The terminal block forms a hermetic seal with the exterior surface of the housing wall that encircles the aperture. The seal may be formed by welding the terminal block to the exterior housing wall surface and the terminal block may be positioned entirely outwardly of the exterior surface of the housing wall and have a concave surface for engaging the housing wall. A cover may also be provided wherein the cover has a plurality of radially inwardly projecting tabs that are engageable with a latching surface on the terminal body. The latching surface may be formed by an annular groove formed in the terminal body.

Abstract: A twin cylinder rotary compressor including first and second cylinders; a crankshaft having first and second eccentrics mounted thereon, the first eccentric disposed within the first cylinder, the second eccentric disposed within the second cylinder; and a separator plate disposed between the first and second cylinders and having a first piece and a complementary second piece. Each of the first and second pieces includes an interior surface defining a semi-circular recess. The interior surface and the semi-circular recess of the second piece is complementary to the interior surface and the semicircular recess of the first piece, respectively, such that the semi-circular recesses combine to form a circular bore, which closely captures a portion of the crankshaft located between the first and second eccentrics.

Abstract: A compressor assembly having a drive shaft supported by a main bearing and an outboard bearing located on opposite axial ends of a cylinder block. The main bearing has a bearing support formed therein in which first and second apertures are defined. The diameter of the first aperture is less than the diameter of the second aperture. The shaft extends through the first and second apertures with the diameter of the drive shaft having an outer diameter which is no greater than the diameter of the first aperture. A sleeve is mounted on the drive shaft and is at least partially disposed within the second aperture. A bearing is located in the second aperture and engages the sleeve and the main bearing to rotationally support the drive shaft. The sleeve can have a thickness which allows the bearing to be of a standard size rather than a custom size.