One of the latest design approaches for air-to-water and water-to-water heat pumps is called “direct-to-load” piping. It’s based on the ability of a inverter-driven scroll compressor to operate over a wide range of speeds, and to handle on/off cycling when necessary, without the frequent inrush current demands associated with short-cycling a fixed speed compressor. The concept of direct-to-load piping using an air-to-water heat pump with it’s own internal circulator is shown in figure 1.
