I would like to simulate a primary-only hot water loop, and the hot water pump is riding the pump curve which means one-speed pump. It is expected that the pump rides its curve as the flow varies, and the hot water loop flow rate could vary based on the load. In order to model the one-speed pump, I use "Pump:ConstantSpeed". Then I check "Pump Mass Flow Rate" in results. It seems the hot water loop is actually constant flow and gpm never changes.
Is there anything wrong in my setup? Or any other setup needed such as bypass?