ABSTRACT
This chapter describes building temperature controls and the associated flow and pressure controls. Flow control loops are cascaded with temperature control loops in pressure-independent variable-air-volume boxes and are used in air-handling units to regulate the outdoor air flow rate. For outdoor air flow control loops and cooling based on the use of cool outdoor air, overshooting may be a problem when the outdoor air temperature is below freezing. The chapter considers algorithms for modulating valves, dampers, and other devices to control temperature, pressure, or flow. The temperature difference between the water leaving the condenser and the water leaving the evaporator is strongly correlated with the pressure difference across the compressor. Therefore, the chiller power can be reduced if the leaving water temperature difference can be reduced. The temperature difference between the water leaving the condenser and the water leaving the evaporator is strongly correlated with the pressure difference across the compressor.
