Abstract: Axial flow fan propellers are provided with a roughened portion along the trailing edge of the fan blades on the pressure side of the blade to minimize tonal acoustic emissions generated by laminar boundary layer vortex shedding. The roughened portion may be provided by trip surfaces formed in the blades, by strips of abrasive material adhered to the blades along the trailing edges, respectively, by parallel or cross-hatched serrations in the blades or by upturned or offset trailing edges of the blades. The height of the roughened portion should be about equal to the boundary layer thickness of air flowing over the blade surfaces during operation of the fan. The fan propellers are particularly advantageous in heat exchanger applications, such as residential air conditioning system condenser units.

Abstract: A device is provided for dampening compressor-induced vibration in an air conditioning system of the type having an indoor unit, an outdoor unit and a refrigerant conduit therebetween. The outdoor unit includes a compressor that is operable to circulate a vapor compression refrigerant through the conduit between the indoor and outdoor units. The device is comprised of a support member containing a section of refrigerant line. The support member is located beneath the outdoor unit and the refrigerant line section is interposed in a portion of the refrigerant conduit between said compressor and said indoor unit, such that the refrigerant flowing between the indoor unit and the compressor is routed through the line section in the outdoor unit support member.

Abstract: A device is provided for dampening compressor-induced vibration in an air conditioning system of the type having an indoor unit, an outdoor unit and a refrigerant conduit therebetween. The outdoor unit includes a compressor that is operable to circulate a vapor compression refrigerant through the conduit between the indoor and outdoor units. The dampening device is comprised of plural vibration dampening elements spaced along the conduit, with the spacing between adjacent elements corresponding to the wavelength of a natural vibratory frequency of the conduit. The device is preferably located proximate to the compressor and inside of the outdoor unit cabinet in which the compressor is housed. Various embodiments of the dampening device are disclosed.

Abstract: A drain pan for capturing condensate from a cooling coil in an air conditioning system is configured to facilitate condensate drainage from the pan and to inhibit accumulation of condensate therein. The pan includes troughs for collecting condensate and for channeling the condensate to the front part of the pan where the drain openings are located. A back trough has a central hump to enhance the flow of condensate from the back trough in both directions into opposed side troughs. The side troughs are sloped from back to front to conduct the condensate into a front trough to facilitate drainage from the pan. The lowermost portion of the front trough region is defined by a relatively narrow, non-flat area to reduce the amount of condensate residue in the pan.

Abstract: Air conditioning apparatus is provided in which an air blower and an electric heater assembly are located in a common housing with the heater assembly projecting into the housing from a wall thereof in transverse relationship to the blower. This configuration eliminates the need for a dedicated space for the electric heater downstream of the blower housing, which reduces the size of the apparatus. The wall of the housing includes an opening through which the heater assembly is insertable into the housing. The heater assembly includes a mounting plate to close off the wall opening and to removably mount the heater assembly with the housing. The heater assembly preferably further includes an open coil electric heater, with a major dimension of the heater being oriented generally parallel to the direction of air flow in the blower housing.

Abstract: A tubular heat exchanger has at least one pair of dimples which are extruded into at least one tube of the heat exchanger by deforming the tube wall inwardly. The dimples of each pair are in generally facing relationship, but are offset with respect to each other along a longitudinal axis of the tube, which slows down the flow of flue gas in the tube when the heat exchanger is in operation and increases the turbulence of the gas, thereby enhancing the transfer of heat from the flue gas to air flowing across the outer surfaces of the heat exchanger. The offset design allows each dimple to protrude beyond the centerline of the tube, which alters the direction of the flue gas flowing in the tube.

Abstract: A combination water heating and space heating apparatus includes a water heating unit and a space heating unit. The water heating unit has a water storage tank, a heating device for heating water stored in the tank, and a first temperature sensor for sensing water temperature. The space heating unit includes a heat exchanger for heating air supplied to an indoor space, a blower for blowing air over the heat exchanger, and a second temperature sensor for sensing air temperature in the space. Heated water is supplied from the tank to the heat exchanger by means of a circulation pump when the second temperature sensor indicates a demand for heat in the space. The apparatus is controlled to give priority to domestic hot water use (e.g., potable water) over space heating use.

Abstract: In accordance with the present invention, a space conditioning system having multi-stage cooling and dehumidification capability is provided. The system includes plural refrigeration circuits operable in a cooling mode to provide cooled air to an indoor space. At least one of the refrigeration circuits is also operable in a reheat mode, wherein air is dehumidified by cooling it and then reheating it before it is supplied to the space. A control system is provided for controlling the operation of the refrigeration circuits to satisfy both a demand for cooling and a demand for dehumidification. Depending upon the level of demand for cooling, the system is operated to satisfy the dehumidification demand and the cooling demand simultaneously. However, in response to a higher level of demand for cooling (e.g., a second stage demand, or in some cases, a higher demand), the demand for cooling takes priority over the dehumidification demand.

Abstract: A resilient article and method of manufacturing the same using recycled materials are described. Predetermined amounts of thermoset material and thermoplastic binder are mixed and extruded into a die, from which the mixture emerges in the form of a sheet having the approximate thickness of the finished article. The mixture then enters a calibrator, which more precisely shapes the sheet to the desired thickness. The sheet is then cooled and cut to the desired dimensions to provide the finished article. The thermoset material used in the mixture is preferably ground vehicle tire rubber with the fabric and metal removed and the thermoplastic binder is preferably waste polyethylene. The apparatus and method according to the present invention is particularly well suited for manufacturing resilient articles for use as expansion joint material.

Abstract: In accordance with the present invention, a method of determining refrigerant charge level in a space temperature conditioning system includes the steps of establishing a relationship between at least one selected system operating parameter and refrigerant charge level, independent of ambient temperature conditions; measuring the selected parameter(s) while the system is in operation; and using the established relationship and the measured parameter(s) to determine the refrigerant charge level. In one embodiment of the invention, both condenser subcooling and evaporator superheat parameters are measured and the predetermined relationship between charge level and each of these parameters is used to determine the actual refrigerant charge level.

Abstract: In a gas-burning apparatus, such as a furnace, a device for reducing NOx emissions includes a cup member mounted proximate to an inlet to a combustion chamber of the apparatus and a perforate member attached to the cup member and located in the combustion chamber at a predetermined distance inwardly from the inlet. The perforate member has a plurality of holes to define a mesh pattern through which the flame and other products of combustion are constrained to pass within the combustion chamber. The perforate member acts as a heat sink to reduce the flame temperature, thereby inhibiting NOx production.

Abstract: In accordance with the present invention, a method of determining acceptability of a selected condition in a space temperature conditioning system is comprised of the steps of perturbing the system while it is in operation by changing operation of at least one component thereof; sensing a change in a first operating parameter of the system in response to the changing step and generating a control signal in response to the change in the first operating parameter being greater than a predetermined limit; sensing a change in a second operating parameter of the system during a period beginning with the perturbing step and ending with the control signal; comparing the change in the second operating parameter with a reference corresponding to an acceptable condition; and determining acceptability of the selected condition in response to the comparing step.

Abstract: A space conditioning system for controlling the temperature and humidity of air within an enclosed space includes a vapor compression refrigeration unit having a reheat coil disposed downstream of the system evaporator coil to reheat return air after cooling and condensation of excess water vapor in the return air by the evaporator coil. The system includes a damper for controlling inflow of ambient outdoor air, depending on the total enthalpy of the outdoor air, so as to satisfy cooling and the dehumidification requirements without operating the refrigeration unit when the enthalpy of the outdoor air is suitable. The system includes a programmable controller for controlling air temperature and humidity within the enclosed space by sensing outdoor air enthalpy, temperature and humidity of air within the enclosed space and temperature or enthalpy of supply air being admitted to the enclosed space.

Abstract: In a space conditioning system, such as a central air conditioning or heat pump system, a unit of the system has a heat exchanger made of a predetermined first type of metal (e.g., aluminum) and a cabinet in which the heat exchanger is mounted, which is made of a second type of metal (e.g., steel). A device is provided for isolating the heat exchanger from the cabinet to prevent contact therebetween. The isolation device preferably includes plural snap-fit plastic members spaced along the top and bottom of the heat exchanger, plural mounting brackets made of the first type of metal on each end of the heat exchanger and a pair of plastic bushings operatively associated with each mounting bracket and extending through aligned holes in the corresponding mounting bracket.

Abstract: In a space cooling system having an evaporator in heat exchange relationship with a space to be cooled, a condenser external to the space, a compressor for circulating heat transfer fluid between the evaporator and condenser, an expansion valve for controlling the flow rate of heat transfer fluid through the evaporator, apparatus for automatically closing the expansion valve in response to a loss of electrical power to the system. The apparatus includes a storage capacitor for storing electrical energy when power is being supplied to the system, a voltage detector for detecting a loss of electrical power and a controller for controlling a step motor to close the expansion valve in response to a loss of system power. The capacitor automatically discharges in response to a power loss condition to supply power to the controller and step motor to enable the expansion valve to be closed. Therefore, refrigerant migration in the system, which can damage the compressor upon restart, is substantially inhibited.

Abstract: Apparatus is provided for sampling gas in operative association with a combustion appliance, such as a furnace. The combustion appliance includes a first conduit through which combustion air is supplied to the appliance and a second conduit through which gas heated by the appliance is discharged from the appliance. The sampling apparatus includes a third conduit communicating between the first and second conduits and a gas sensor operable to sense a selected gas in the heated gas present in the third conduit. Operation of the appliance creates a pressure difference between the first and second conduits to draw a sample of heated gas from the second conduit into the third conduit, so that no mechanical device, such as a pump, is needed to transport the sample of heated gas to the gas sensor. A temperature sensor is provided for sensing temperature of the gas in the third conduit to verify gas flow in the third conduit.

Abstract: An evaporator for evaporating a phase change refrigerant in a space conditioning system such as an air conditioner, heat pump or refrigeration system, is provided. The evaporator includes an inlet for introducing the refrigerant into the evaporator, an outlet for discharging the refrigerant from the evaporator and plural conduits defining a plurality of hydraulic flow paths between the inlet and the outlet. In accordance with the invention, a separator is provided to substantially separate liquid refrigerant from vapor refrigerant before the refrigerant is introduced into the evaporator to enhance refrigerant distribution within the evaporator, thereby improving evaporator performance.

Abstract: An evaporator for evaporating a phase change refrigerant in a space conditioning system, such as an air conditioner, heat pump or refrigeration system, is provided. The evaporator includes an inlet for introducing the refrigerant into the evaporator, an outlet for discharging the refrigerant from the evaporator and plural conduits defining a plurality of hydraulic flow paths between the inlet and the outlet. In accordance with the invention, a separator is provided to substantially separate liquid refrigerant from vapor refrigerant before the refrigerant is introduced into the evaporator to enhance refrigerant distribution within the evaporator, thereby improving evaporator performance.

Abstract: An improved defrost controller is provided for a space cooling system of the type having an evaporator in heat exchange relationship with a space to be cooled, a condenser external to the space, a compressor for circulating heat transfer fluid between the evaporator and condenser, an expansion valve located between an outlet from the condenser and an inlet to the evaporator, and a defroster operatively associated with the evaporator. The expansion valve is positionable in a plurality of positions between a fully open position and a fully closed position to maintain a desired level of superheat across the evaporator. The defrost controller monitors the expansion valve position and activates the defroster in response to the expansion valve being in a more closed position than a predetermined defrost target position.