Abstract: An airhandling unit for an HVAC system includes a cabinet having an electric motor driven centrifugal blower disposed therein. The blower includes a scroll or volute type blower housing which may be formed of opposed releasably connectable housing parts. The blower housing parts include opposed sidewalls with axially extending compound curved portions which cooperate with an end wall which is configured to have portions which are not of substantially constant increasing radial distance from the blower impeller axis of rotation. However, a constantly increasing airflow cross-sectional flow area is provided within the blower housing for blower discharge air. The disposition of the blower housing sidewalls with respect to the cabinet walls provides improved airflow distribution for air flowing into the blower air inlet openings.

Abstract: An enhanced touch-screen display system is disclosed for generating pixel coordinate estimates corresponding to a location on a display screen touched by a user. The system is an analog resistive touch-screen display system having a processor and associated software algorithms to allow for the calibration and validation of pixel coordinate estimates as an integral part of the real-time generation of the pixel coordinate estimates. Multiple calibrated pixel coordinate estimates are generated and processed at a pre-defined sampling rate to determine a valid pixel position to minimize sampling delays due to settling times. The x-axis position is also validated before the system attempts to generate a y-axis position to avoid the wasted time for generating y-axis estimates when x-axis estimates are corrupted. Noisy estimates are inherently reduced in the touch-screen display system by providing shunts across certain drivers in the system that also allow for detection of a “no touch” state.

Abstract: A forced airflow air conditioning system includes a humidifier which is operable to humidify air bypassed from a supply air plenum to a return air duct or vice versa, the humidifier airflow being controlled by a damper closure member which is operably connected to a bimetal spring actuator or to an electric motor, both responsive to temperature of air flowing through the system. One embodiment includes an electric motor connected to the damper closure member and in circuit with a humidistat for opening the damper when humidification is required.

Abstract: A method identifies at what outdoor temperature a heating or cooling system will need to operate at full capacity (e.g., 100% duty cycle) to maintain a desired indoor temperature. The tolerable outdoor temperature limit is identified by extrapolating data collected upon sampling the system's performance (e.g., duty cycle) at various loads (e.g., difference between outdoor temperature and the indoor temperature). In a similar manner, the method can also predict a best achievable indoor temperature for a given outdoor temperature. The tolerable outdoor temperature limit and best achievable indoor temperature can be displayed to indicate whether the system needs servicing.

Abstract: An HVAC system includes a desiccant wheel, wherein the wheel's speed varies with airflow, the wheel is energized for at least a set period at startup, and/or a heat recovery system (e.g., an air-to-air heat exchanger) upstream of the wheel enhances the system's ability to dehumidify air.

Abstract: A communications protocol for a communications bus wherein messages are transmitted to a plurality of devices communicating by a bus. Each message includes a unique code indicating the end of the message and that same unique code triggers a transfer of communications control to another device of the plurality of devices.

Abstract: A blower housing. The blower housing comprises an axis about which the blower housing is oriented; an inlet allowing the entrance of fluid in an axial direction for the blower housing; a discharge for the blower housing discharging fluid in a radial direction; a cutoff for the blower housing extending in the axial direction and located in the vicinity of the outlet; and a fluid flow path extending from the cutoff to the outlet. The fluid flow path is open in a radial inward direction to the axis to receive fluid from the inlet. The fluid flow path has a progressively increasing cross-sectional area, and the fluid flow path alternately expands and contracts in the radial and axial directions.

Abstract: A cabinet for air handling equipment includes two similarly sized covers that are each nonsymmetrical about their vertical centerline. Each cover has an original supply or return air duct opening plus space for an alternate opening. The original and alternate openings are of different shapes to accommodate round or rectangular ducts. The two covers can be interchanged with each other and inverted to provide various supply and return air duct configurations.

Abstract: A temperature conditioning system includes a damper system that determines the pattern of airflow through two coil slabs of an indoor heat exchanger, wherein the heat exchanger is preferably part of a split-system air conditioner or a heat pump. In a normal mode position, the damper system directs the airflow in a parallel flow relationship through the two coil slabs for optimum capacity and efficiency. In an enhanced mode position, the damper system directs the airflow in a series flow relationship through the two coil slabs. The enhanced mode position not only helps reduce humidity when the temperature conditioning system operates in a cooling mode but also helps raise the supply air temperature at a room register when the system is operating in a heating mode. In some embodiments, the damper system is also movable to a bypass position that allows the air to bypass the indoor heat exchanger.

Abstract: A cabinet for air handling equipment includes a door assembly having features such as inner and outer door panels being held together and sealed by double-sided tape, which acts as a thermal break, a latch that prevents a door gasket from being crushed due to positive or negative air pressure within the cabinet, and a doorframe that is easy to assemble and install for either right-hand or left-hand swinging doors. To assemble adjacent pieces of the doorframe, sheet metal tabs of one piece are inserted into slits of the other piece. The tabs are then twisted to hold the adjacent pieces of the doorframe together.

Abstract: An HVAC system includes a desiccant wheel, wherein the wheel's speed varies with airflow, the wheel is energized for at least a set period at startup, and/or a heat recovery system (e.g., an air-to-air heat exchanger) upstream of the wheel enhances the system's ability to dehumidify air.

Abstract: Heat exchange apparatus includes elliptical cross section heat exchange tubing provided with a partition dividing the interior of the tubing into at least two parallel flow passages. The flow passages are delimited by inwardly projecting fins formed on the tubing wall and on the partition, the fins extending parallel to each other and having a height less than the anticipated thickness of the velocity boundary layer of heat exchange fluid flowing through the tubing passages. The tubing may be arranged in serpentine or coiled arrangements of the heat exchange apparatus or parallel tubes extending between heat exchanger header tanks. The heat exchange apparatus is particularly adapted for use in HVAC systems.