Circulator pumps are small, single-stage, overhung, rotodynamic pumps supported in-line by system piping. This measure addresses the two most common applications for these pumps: hydronic heating and domestic hot water (DHW) recirculation to provide hot water on demand. For both applications, energy savings can be achieved by using electronically commutated motors (ECMs) rather than induction motors. In DHW recirculation applications, on/off control of the recirculator can be used to manage the temperature of the recirculation loop and/or times that the loop is kept hot. This not only reduces pump energy relative to no controls, but – more significantly – reduces the hot water heater load required to compensate for recirculation loop heat losses. In hydronic heating systems, speed control of ECMs can lower pump power consumption when full speed is not needed to meet the heat transfer demand. This measure addresses circulator pumps with motors to 5 HP. The motors must be ECMs. The application (hydronic heating, DHW recirculation), control type, and (for DHW recirculation) water heater type are measure identifiers. Installations where an efficient circulator pump and/or controls are required by code are not eligible for this measure.
