A user's perspective on the application of adjustable speed drives and microprocessor control for HVAC savings

Installation of an automatic air-conditioning control system has been found to maximize chiller efficiency, minimize the number of chilled water pumps operating while maintaining adequate capacity, and control the air volume by varying the fan speed to move only the air required to maintain desired room conditions. Project payback was typically less than three years, depending on energy costs, with the space conditions actually improving by providing a more even control of temperature and humidity. Details are discussed including selection of control equipment, calculation of savings, motor load reading techniques, and adjustable-speed drive fundamentals involved in selection of equipment.<>