I'm going to have 3 separate pumps for 3 zones,BB hot water,gas. Do you establish a flow rate for each zone (f=Q/500 X 20) (http://www.taco-hvac.com/uploads/FileLibrary/SelectingCirculators.pdf). The f that you get,you are suppose to go to the chart and tells you the size of pipe. Is this pipe size the size that is suppose to go into the pump and or the pipe going out of the pump.