Abstract: A subcooler is provided in heat exchange relationship with the high pressure liquid refrigerant line flowing to the indoor coil, such that when a low pressure condition is sensed on the low pressure side of the system, the subcooler flashes a portion of the liquid refrigerant to the low pressure side to thereby maintain suction pressure to the compressor, while at the same time subcooling the liquid refrigerant flowing to the fan coil to thereby increase its efficiency.

Abstract: An adaptive defrost system for a heat pump wherein the time-between-defrosts is continuously updated by multiplying the last time-between-defrosts by a ratio of the desired and actual differences between the pre-defrost and after-defrost saturated coil temperatures. A single thermistor is used for both pre and after-defrost measurements such that no calibration is required.

Abstract: Provision is made in a multiple zone air conditioning system for varying the speed of the compressor to match the load thereon. The differences between the actual temperatures and the set points in the individual zones are monitored and the largest of these differences is periodically selected and applied to a transfer function to obtain a new speed at which the compressor is run. At the same time, the individual dampers within the zones are modulated in response to their respective sensed temperature differences. Provision is also made to vary the speed of the indoor fan in a similar manner.

Abstract: The base pan of a heat pump has a plurality of drainage openings formed near the periphery thereof such that either a single row coil or a multiple row coil heat exchanger may be used therewith to obtain adequate drainage of defrost liquid while at the same time preventing any downward movement of molten metal or hot particles through the drainage openings. The openings are located directly under the single or outside coil and a slanted shelf is placed directly under the location where the inner coil(s) would be placed, with the slanted shelf acting as a barrier for hot materials in a single coil apparatus and as a conduit for drainage to the opening when used with a multiple coil apparatus.

Abstract: Vertical support for the coil within a base pan is provided by way of a plurality of raised support surfaces that are formed to define on the radially outward side an opening that facilitates the inwardly extending fastener which secures the protective grille to the base pan skirt. Damage that might otherwise be caused to the coil by the fastener, is thus avoided.

Abstract: An electronic control box is provided with an internally disposed vent channel which carries ambient air from a bottom opening to the top portion of the control box. The cooling air is then caused to flow downwardly through the control box and over the electronic components by way of a bottom opening which is fluidly connected by a vent tube to a negative pressure area created by the fan. The flow of cooling air through the control box is therefore promoted while maintaining the water-tight integrity of the box.

Abstract: The interface bracket, which supports a sealing gasket between the lower surface of a base pan and the front face of a sleeve lower wall, is designed so as to extend under the sleeve lower wall so as to overlap and support the lower wall from sagging. The integrity of the sealing relationship is therefore maintained. Provision is also made to automatically cam the sleeve lower wall from a sagged position by the use of a bracket with an angled leading edge.

Abstract: A method and apparatus for lacing hairpin tubes into plate fin bundles by the continuous movement of plate fins from one end of horizontally supported guide rods to the other end thereof where they pass onto aligned tubes. The horizontal guide rods are precisely positioned by a number of clamps applied along their lengths. Provision is made to successively remove and reapply the clamps in such a way as to permit the selective movement of the fins along the guide rods while maintaining the guide rods in their fixed positions. The guide rods are graduated in various diameters to facilitate the easy movement of the plate fins and hairpin tubes thereon while providing for precise relative placement of the plate fins and the hairpin tubes.

Abstract: A method and apparatus for maintaining the desired level of excess air in a two stage gas furnace system. Low and high pressure switches are placed across the heat exchanger and are successively closed, as the inducer motor accelerates during purging, when the pressure drop reaches the respective theoretically desired low and high firing pressure drop levels. As the switches are closed, the inducer motor speeds are sensed and recorded, with a ratio of the two then being calculated. After firing, the ratio is then directly applied to a desired high firing motor speed to obtain the desired low firing motor speed.

Abstract: An emergency heat bypass arrangement for a furnace in which the normal controller path is supplemented by an alternate path through a relay subject to an emergency heat switch controlling the solenoid of the relay, and the relay includes additional contacts for keeping power on the solenoid even after the furnace high pressure switch changes contacts to provide heating when said controller has malfunctioned.

Abstract: The control box for a refrigeration condensing unit has a heat sink mounted on its rear side between the control box and the coil assembly, the heat sink being in the flow path of the cooling air flowing in thru the coil such that the heat dissipation therefrom is substantially enhanced. The heat sink has a plurality of fins formed on its rear side, with the fins extending across the relatively narrow width of the heat sink such that the cooling air flows over the entire length of each of the fins and provides a substantially uniform velocity profile along the heat sink vertical axis.

Abstract: Method and apparatus effective for emplacing a ring (52) at a selected axial location of a pipe (45) by reducing its diameter and establishing a circumferential bulge (146) adjacent to the selected location and ring (52), said bulge (146) cooperatively resisting axial displacmeent thereof and being in physical conformity therewith.

Abstract: A self-correcting control system and method is provided for a furnace to correct certain operating conditions that exceed normal limits. Upon sensing insufficient air flow as a function of the pressure drop across the heat exchangers, the control system and method cause the inducer motor to increase in speed, thereby to increase the flow of combustion air. Similarly, upon sensing that the flow of air to be heated exceeds a predetermined temperature, the control system and method will increase the speed of the air blower to increase the flow rate of air to be heated through the furnace, thereby resulting in lowering the temperature of the air to be heated below the predetermined temperature. Upon sensing a gas flow leak through the gas regulator, the control system and method will recycle the gas regulator to properly seat a gas flow control valve therein. If none of the self-correcting features correct the particular occurring problem, the control system and method will shut down the furnace.

Abstract: The power output of a variable speed motor is limited to a safe level by determining the maximum allowable speed corresponding to a maximum power output limit over a range of load conditions and then maintaining the speed of the motor below those maximum allowable speeds at the particular load conditions existing at the time.

Abstract: Method and apparatus for maintaining excess air control in a gas furnace. A pressure switch is placed across a heat exchanger to indicate when, while accelerating the inducer motor speed during purging operation, the pressure drop reaches a predetermined level. When that occurs, the motor speed is sensed and recorded. When the furnace is subsequently fired, the desired inducer motor speed is obtained by modifying the recorded motor speed on a correction factor derived from empirical data obtained from a gas furnace operating under selective variable conditions.

Abstract: In an air conditioning system having a condensate tube interconnecting a condensate pan and a trap, a vent is provided in the condensate tube for relieving any internal pressure which would otherwise cause a restriction of condensate flow within the condensate tube.

Abstract: An integrally threaded brass insert is molded into the discharge conduit of a condensate pan such that a steel drainage pipe can be threadably engaged to the insert without causing damage to the plastic discharge conduit. Bonding between the insert and the surrounding conduit is enhanced by providing a knurled surface on the outer periphery of the insert.

Abstract: A coupling mechanism is provided for coupling an expansion device in a liquid refrigerant line of a refrigeration system. The coupling mechanism permits the expansion device to be removably coupled to the liquid refrigerant line, thereby permitting the expansion device to be easily decoupled and recoupled to the liquid refrigerant line.

Abstract: Method and apparatus are provided for mounting an air conditioner in a wall opening with a single bracket attached to the lower wall and extending upwardly into the wall opening. The air conditioning housing is formed with a lip on its upper surface to engage the inner surface of the upper wall, and an indent on its lower wall to receive the upwardly extending bracket when the air conditioner slips down into its installed position. Means are provided to secure the bracket to the air conditioner housing to prevent removal of the system from outside the building.