Abstract: A heating system includes a refrigerant boiler including a heat source for heating a refrigerant from a liquid state to a vapor state, a boiler outlet and a boiler inlet; a heat exchanger in fluid communication with the refrigerant boiler, the heat exchanger including a upper manifold having a heat exchanger inlet coupled to the boiler outlet, a lower manifold having a heat exchanger outlet coupled to the boiler inlet and a plurality of tubes connecting the upper manifold and the lower manifold, wherein refrigerant passes from the upper manifold to the lower manifold via gravity; and a fan moving air over the heat exchanger to define supply air for a space to be heated.

Abstract: A heating system includes a refrigerant boiler including a heat source for heating a refrigerant from a liquid state to a vapor state, a boiler outlet and a boiler inlet; a heat exchanger in fluid communication with the refrigerant boiler, the heat exchanger including a upper manifold having a heat exchanger inlet coupled to the boiler outlet, a lower manifold having a heat exchanger outlet coupled to the boiler inlet and a plurality of tubes connecting the upper manifold and the lower manifold, wherein refrigerant passes from the upper manifold to the lower manifold via gravity; and a fan moving air over the heat exchanger to define supply air for a space to be heated.

Abstract: A method for fan speed control for a condenser fan in an air conditioning system includes determining a refrigerant condition at an inlet of a compressor by a condenser fan speed control module; determining a refrigerant condition at an outlet of the compressor by the condenser fan speed control module; determining a parabolic curve of a relationship between an air conditioning system performance metric and a speed of the condenser fan based on the determined inlet condition and the determined outlet condition by the condenser fan speed control module; identifying an optimum condenser fan speed based on a vertex of the parabolic curve by the condenser fan speed control module; and controlling the speed of the condenser fan to meet the optimum fan speed by the condenser fan speed control module.

Abstract: A rooftop air conditioning unit to provide conditioned air to a conditioned space within a building is provided and includes a housing, disposed on a roof of the building roof, defining a pathway from an inlet fed by exterior and/or interior air to an outlet leading to the conditioned space and a hydronic heating system disposed within the housing to heat the air traveling along the pathway.

Abstract: A method for fan speed control for a condenser fan in an air conditioning system includes determining a refrigerant condition at an inlet of a compressor by a condenser fan speed control module; determining a refrigerant condition at an outlet of the compressor by the condenser fan speed control module; determining a parabolic curve of a relationship between an air conditioning system performance metric and a speed of the condenser fan based on the determined inlet condition and the determined outlet condition by the condenser fan speed control module; identifying an optimum condenser fan speed based on a vertex of the parabolic curve by the condenser fan speed control module; and controlling the speed of the condenser fan to meet the optimum fan speed by the condenser fan speed control module.

Abstract: A rooftop air conditioning unit to provide conditioned air to a conditioned space within a building is provided and includes a housing, disposed on a roof of the building roof, defining a pathway from an inlet fed by exterior and/or interior air to an outlet leading to the conditioned space and a hydronic heating system disposed within the housing to heat the air traveling along the pathway.

Abstract: A rooftop air conditioning unit, including an air conditioner to produce conditioned air for a conditioned space within a building, the air conditioner having an evaporator, a compressor operably disposed downstream from the evaporator and a condenser operably interposed between the compressor and the evaporator, the rooftop air conditioning unit including a housing, disposed on a roof of the building to house the evaporator, the compressor and the condenser, the housing being formed to define a pathway from an inlet that is fed by exterior and/or interior air to an outlet leading to the conditioned space and a heat reclaim module disposed within the housing and operably coupled to the air conditioner to be receptive of heat produced in the air conditioner for heat exchange operations.

Abstract: A heating system includes a refrigerant boiler including a heat source for heating a refrigerant from a liquid state to a vapor state, a boiler outlet and a boiler inlet; a heat exchanger in fluid communication with the refrigerant boiler, the heat exchanger including a upper manifold having a heat exchanger inlet coupled to the boiler outlet, a lower manifold having a heat exchanger outlet coupled to the boiler inlet and a plurality of tubes connecting the upper manifold and the lower manifold, wherein refrigerant passes from the upper manifold to the lower manifold via gravity; and a fan moving air over the heat exchanger to define supply air for a space to be heated.

Abstract: An air conditioning system is disclosed which takes advantage of low ambient temperature conditions so as to activate a refrigerant flow that bypasses the compressor. The activation of the refrigerant flow is achieved by the intelligent control of a pump positioned between the outlet of the condenser and the inlet of an expansion device upstream of the evaporator. The refrigerant flow produced by the pump does not require any particular positioning of the condenser and evaporator components with respect to each other. The evaporator preferably absorbs heat from water circulating in a secondary loop which is used to remove heat from a building by one or more fan coil units.

Abstract: An air conditioning system is disclosed which takes advantage of low ambient temperature conditions so as to activate a refrigerant flow that bypasses the compressor. The activation of the refrigerant flow is achieved by the intelligent control of a pump positioned between the outlet of the condenser and the inlet of an expansion device upstream of the evaporator. The refrigerant flow produced by the pump does not require any particular positioning of the condenser and evaporator components with respect to each other. The evaporator preferably absorbs heat from water circulating in a secondary loop which is used to remove heat from a building by one or more fan coil units.

Abstract: The present invention is a method for operating an air conditioner chiller system under high ambient air conditions. When the temperature of the standard discharge saturation temperature increases above a first predetermined temperature as a result of a rise in ambient air temperature, an expansion valve is throttled to reduce the capacity of the system compressor. The amount of throttling can be made to be dependent on the amount that the discharge temperature exceeds the first predetermined temperature so that compressor capacity is reduced by an amount no more than is necessary to assure that a maximum operating design pressure is not exceeded.

Abstract: An improved cooler with level sensor for measuring variation in the liquid refrigerant level of a refrigerant within the cooler, comprises a cooler shell for holding the refrigerant, heat exchanger tubes for carrying the liquid to be cooled, and a liquid refrigerant level sensor comprising a probe extending to a point above the heat exchanger tubes, one or more thermistors; and a heating element. When the probe is totally within the vapor refrigerant above the heat exchanger tubes, the heater raises the temperature of the thermistors above the saturation temperature of the refrigerant. As the liquid refrigerant level begins to rise, the liquid refrigerant comes in contact with the outside of the probe. Since the heat transfer coefficient of the liquid refrigerant is significantly higher than that of the vapor refrigerant, the probe in that area is quickly cooled to the saturation temperature.

Abstract: An oil separator for a refrigeration system having two inlets for receiving two streams of a mixture of oil and refrigerant for separation. One inlet is on each side of the oil separator. This allows for a separator with a smaller diameter to be used to achieve the same preferred speed of travel of the oil-refrigerant mixture.

Abstract: The present invention is a method for controlling oil lubricant pressure of a screw type compressor in an air conditioning system. In response to a low oil pressure condition, evaporator pressure is lowered to increase the pressure differential across a compressor, to thereby bring about an increase in oil pressure. Evaporator pressure can be lowered by decreasing the maximum operating pressure of the evaporator, and by throttling an expansion valve by the amount required to lower the evaporator pressure in accordance with the reduced maximum operating setpoint.

Abstract: A method and control system are disclosed for operating a refrigeration system to protect an evaporator in a refrigeration system against freezeups of a heat transfer fluid cooled in the evaporator by operation of the refrigeration system. A first signal indicative of the temperature of the heat transfer fluid in the evaporator and a second signal indicative of the temperature of the heat transfer fluid leaving the evaporator are provided to a microcomputer system which processes the first and second signals to determine when the temperature of the heat transfer fluid in the evaporator falls below the temperature of the heat transfer fluid leaving the evaporator by a selected amount. The microcomputer system generates an alarm signal to shut down operation of the refrigeration system if the microcomputer system determines that the temperature of the heat transfer fluid in the evaporator is less than the temperature of the heat transfer fluid leaving the evaporator by the selected amount.