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.
heat pump in American English. a device for cooling or warming an enclosed space by removing heat from interior air and transferring it out, or by absorbing heat from outdoor air, or from a hot-water source, and transferring it in.