Kirchhoff's loop rule (otherwise known as Kirchhoff's voltage law (KVL), Kirchhoff's mesh rule, Kirchhoff's second law, or Kirchhoff's second rule) is a rule pertaining to circuits, and is based on the principle of conservation of energy.
ECM stands for Electronically Commutated Motor. Basically, circulator pumps with ECM motors offer intelligent speed control. Speed-controlled pumps automatically adjust their output to changing demand, whether it be due to outside temperature, level of sunlight, overall activity, and other heating sources. The benefit of having a more efficient ECM motor pump is substantial energy savings, which directly relates to cost savings.
The ECM is a type of electronic control unit (ECU), which is an embedded system that employs software to determine the required throttle position by calculations from data measured by other sensors, including the accelerator pedal position sensors, engine speed sensor, vehicle speed sensor, and cruise control switches.