Anyone who has worked on the technical side of the hydronics industry has used terminology such as: pressure, differential pressure, head and head loss. These terms all have legitimate and specific meanings.
John Pughe is a long-time colleague of mine and a true hydronics professional. He recently sent me an “as installed” and “as corrected” schematic for a hydronic heating system with twin 200,000 Btu/hr mod/con boilers, and 15 zones, each powered by its own circulator.