Abstract: A heat pump system comprises a compressor, at least one expansion valve, an accumulator for storing a volume of liquid refrigerant therein, a liquid refrigerant indicator connected to the accumulator to indicate an appropriate refrigerant charge in cooling and heating modes, and a controller. The controller is configured to determine a target compressor discharge pressure based on measured outdoor air temperature and control the compressor discharge pressure by modulating the position of the at least one expansion valve, wherein the higher the target discharge pressure target, the less liquid refrigerant is left in the accumulator. The accumulator can be sized to always have capacity to hold excess refrigerant during heating operations, and can include a charge level indicator so as to allow proper charge of the system in the field without additional tools.

Abstract: Airflow rates within a ventilation system are controlled using motor speed or torque and motor electric current or pressure. Fan speed or torque may be varied to compensate for differing restriction in ductwork, and may provide a constant airflow rate over a range of varying airflow restriction. Air handlers or air conditioning units may be mass produced in common configurations, and installed in different buildings or structures with different ductwork configurations. Methods operate a fan motor at a present speed or torque, sample speed or torque, sample current of the fan motor or pressure within the ventilation system, calculate a present airflow rate within the ventilation system, calculate a new input setting using the present airflow rate and a target airflow rate, change the speed or torque to the new input setting, and repeat these steps to converge on the target airflow rate, often avoiding overshoot.

Abstract: Mixing devices for mixing fuel and air for a premix burner or furnace and furnaces (e.g., premix) with mixing devices. Furnaces may be for heating an occupied space, and may produce lower NOx emissions. A mixing device may be located within an inlet tube, may have a surface that is perpendicular to the direction of fuel flow or that forms a circle, or may have two surfaces held at substantially opposite angles to induce swirl. A portion of the mixing device may extend over an orifice of the fuel injector. A mixing device may be attached to the fuel injector, may be made from a piece of sheet metal, and may have a hole for attachment to the fuel injector. Mixing devices may have a center, two arms, and two ends, which may be separated by bends. A burner plate may be sandwiched between surfaces to allow for expansion.

Abstract: Premix furnace for heating an occupied space while producing lower NOx emissions and methods of mixing air and fuel delivered to a premix burner and of improving combustion stability. A mixing device may be located within an inlet tube, may have a flat surface that is perpendicular to the direction of fuel flow, or may have two surfaces held at substantially opposite angles to induce swirl. A mixing device may be attached to the fuel injector, may be made from a piece of sheet metal, and may have bends and a hole for attachment to the fuel injector. A fluidic diode in the inlet tube may improve combustion stability and may include a hollow frustum or a frustoconical portion, a cylinder concentric with the inlet tube, or a combination thereof. Some embodiments include refractory insulation lining the combustion chamber or may adjust for elevation or fuel characteristics.

Abstract: Air conditioning units packaged with condensing heat exchangers, collectors for such units, and apparatuses for passing a tube through a duct wall and making a loop and trap in the tube. In different embodiments, a drain line may connect to a collector attached to the heat exchanger or condensate may discharge through an inducer fan and out with combustion gasses. A drain line opening in the collector may be lower than a drain hole to the inlet of the inducer fan, which may be lower than an exhaust hole for the fan. A plug in the drain line opening in the collector may be used to discharge condensate through the inducer fan and a bifurcation in the exhaust conduit may separate condensate from most combustion gasses. Embodiments having a drain line connected to the collector may route the drain line through the roof, a conduit, or in the return duct.

Abstract: Air conditioning units packaged with condensing gas heat exchangers where condensate from the heat exchanger passes through the inducer fan, into an exhaust conduit, and out of the unit enclosure, and methods that reduce consumption of fossil fuels using air conditioning units with condensing gas heat exchangers by advertising that the units can be installed on the roof of a building or at ground level. Some embodiments include a drain hole extending through a collector attached to the heat exchanger to the inlet of the inducer fan. In some embodiments, a bifurcation in the exhaust conduit separates condensate from most combustion gasses. Some embodiments discharge condensate into a vertical standpipe in the ground that may extend below the frost line. Various methods include instructing an installer of the units regarding how to install the units and dispose of condensate into the ground or through a drain line into the building.

Abstract: Premix furnace for heating an occupied space while producing lower NOx emissions and methods of mixing air and fuel delivered to a premix burner and of improving combustion stability. A mixing device may be located within an inlet tube, may have a flat surface that is perpendicular to the direction of fuel flow, or may have two surfaces held at substantially opposite angles to induce swirl. A mixing device may be attached to the fuel injector, may be made from a piece of sheet metal, and may have bends and a hole for attachment to the fuel injector. A fluidic diode in the inlet tube may improve combustion stability and may include a hollow frustum or a frustoconical portion, a cylinder concentric with the inlet tube, or a combination thereof. Some embodiments include refractory insulation lining the combustion chamber or may adjust for elevation or fuel characteristics.

Abstract: Relatively constant temperatures are maintained in a space by varying the capacity of heating or cooling equipment. A proportional band is used to adjust capacity to compensate for changes in heating or cooling load, and the proportional band is adjusted to bring the actual temperature within the space closer to the set point temperature. Such an adjustment may be made by determining the difference between the present temperature and the set point temperature, and adjusting a floating temperature set point by a percentage (e.g., ten percent) of the difference. Such a process may be repeated, for example, at regular intervals, such as once per minute. As a result, the temperature within the space approaches (e.g., asymptotically) the set point temperature whether the heating or cooling load is high or low. Methods, systems, and apparatuses are contemplated, including HVAC units and controls, including for residential applications, including using variable-speed drives.

Abstract: Relatively constant temperatures are maintained in a space by varying the capacity of heating or cooling equipment. A proportional band is used to adjust capacity to compensate for changes in heating or cooling load, and the proportional band is adjusted to bring the actual temperature within the space closer to the set point temperature. Such an adjustment may be made by determining the difference between the present temperature and the set point temperature, and adjusting a floating temperature set point by a percentage (e.g., ten percent) of the difference. Such a process may be repeated, for example, at regular intervals, such as once per minute. As a result, the temperature within the space approaches (e.g., asymptotically) the set point temperature whether the heating or cooling load is high or low. Methods, systems, and apparatuses are contemplated, including HVAC units and controls, including for residential applications, including using variable-speed drives.

Abstract: Air conditioning systems that cool and dehumidify spaces within enclosures, buildings having such systems, and methods of controlling humidity within a space. Embodiments adjust speed of a blower or fan motor based on inputs from sensors within the system, using automated processes, to reduce airflow rates to provide for lower temperatures of the cooling coil and to increase the ratio of latent to sensible heat transfer. Fan speeds may be increased as appropriate to avoid frost formation on the cooling coil, to give priority to cooling when temperatures within the space are high, or periodically to provide for mixing within the space.

Abstract: Airflow rates within a ventilation system are controlled using motor speed or torque and motor electric current or pressure. Fan speed or torque may be varied to compensate for differing restriction in ductwork, and may provide a constant airflow rate over a range of varying airflow restriction. Air handlers or air conditioning units may be mass produced in common configurations, and installed in different buildings or structures with different ductwork configurations. Methods operate a fan motor at a present speed or torque, sample speed or torque, sample current of the fan motor or pressure within the ventilation system, calculate a present airflow rate within the ventilation system, calculate a new input setting using the present airflow rate and a target airflow rate, change the speed or torque to the new input setting, and repeat these steps to converge on the target airflow rate, often avoiding overshoot.