Typical applications for circulator pumps are hydronic heating or cooling and potable hot water recirculation to provide hot water on demand. Ciculator pumps are small, single-stage, overhung, rotodynamic pumps supported in-line by system piping. Of the main applications for these pumps, hydronic heating is the largest, both in residential and commercial buildings. These pumps present a high opportunity for savings due to improved motor efficiency and motor speed controls in these applications. Circulators used in domestic hot water applications keep hot water pipes hot to reduce wait time at the end use. The main opportunity for energy savings here is with run-hour, on/off controls.