In this article I explain what a heat pump system is and how it works. In a heat pump system, the heating water is forced to circulate in a heating circuit with a circulating pump. The circulation pump can be installed in the flow pipe (FP) or in the return pipe (RP). However, it has become generally accepted to install the pump in the flow pipe. If you can’t imagine a circulating pump, you will find a modern circulation pump in Fig. 1. [Read more…] about What is a Heat Pump System?