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: A control procedure operates an expansion valve of an air conditioning system. The control procedure utilizes a first control procedure to bring a calculated superheat value within a range of a target superheat value, and a second control procedure to cause the calculated superheat value to match the target superheat value. Both the first and second control procedures preferably use Proportional, Integral, Derivative control algorithms.

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: The invention is directed to an ignition control system that dynamically adjusts the warm-up time of an igniter within a predetermined range depending on the success or failure of the previous ignition or start-up cycle. The system activates the igniter and waits a predetermined or computed warm-up time. At the end of the warm-up time, the system opens a gas valve. The system then waits a preset time from the opening of the gas valve to determine whether ignition was successful or not. If the ignition was successful, the system computes a new igniter warm-up time by decrementing the current time and stores this new value for use during the next start sequence. If the ignition was unsuccessful, the system computes a new warm-up time by incrementing the current value and retrying the start sequence. Preferably, a successful ignition is always determined by checking for the presence of flame a fixed time following the opening of the gas valve.

Abstract: The invention is directed to an ignition control system that dynamically adjusts the warm-up time of an igniter within a predetermined range depending on the success or failure of the previous ignition or start-up cycle. The system activates the igniter and waits a predetermined or computed warm-up time. At the end of the warm-up time, the system opens a gas valve. The system then waits a preset time from the opening of the gas valve to determine whether ignition was successful or not. If the ignition was successful, the system computes a new igniter warm-up time by decrementing the current time and stores this new value for use during the next start sequence. If the ignition was unsuccessful, the system computes a new warm-up time by incrementing the current value and retrying the start sequence. Preferably, a successful ignition is always determined by checking for the presence of flame a fixed time following the opening of the gas valve.

Abstract: Bi-directional fin stock, for use in heat exchangers of the fin and tube type, having louvers formed from the planar surface of the fin stock to project progressively farther into the airstream. This enables the fin stock to exchange heat with a broader airstream by translating the airflow substantially, permitting wider fin spacing.

Abstract: A heater and limit switch assembly, particularly useful for installation in the conditioned air duct of a rooftop air conditioner. The loop of a rigid-loop heater, mounted on a vertical plate by two parallel legs, is modified to provide an inward offset portion leading to the second leg. Radiation, from the offset portion and its bend into the second leg, is received at close range by a simple disk-type limit switch, positioned on the plate outward of the second leg and facing the offset, inducing prompt response to any increase over design temperature.

Abstract: A fin-and-tube heat exchanger designed for one-way airflow, in which louvers, formed from the fin stock, progressively increase in length from the fin leading edge to its trailing edge. Their end walls channel air into stagnant air spaces behind the tubes. The tube collars may be offset somewhat toward the fin trailing edge, further reducing the stagnant air zones. In those bent heat exchangers in which air flows in from outside the curve, offsetting the collars also lessens the angular convergence of fin trailing edges inside the curve and presents less resistance to airflow.