"For the flowrate pumped into the system, you get the pump discharge head from the pump curve. You then should know the flow and pressure at the pump. For each branch end, you must specify either a pressure at the branch end, or a flow from that branch, which will equal the flow in that branch. Then, using one of several possible head loss vs flow equations for pipe flow and the sum of flows into any joint equal to the sum of the outflows from the joint, the unknown value in that segment of pipe, either flow or pressure drop, can be found."
- So let's say I start with the sum of the max demand for each of the branches as the flowrate pumped into the system, then I can easily see that the sum of the flows into the tees will equal the input flow. However, since the demands for each branch can all vary independently, how do you account for separate branch flow under those various conditions? It would seem that there is an infinite number of possibilities...
"The recirculation line does not make a vertical line in any system resistance curve."
- Would it not make a vertical line if there was a flow control valve controlling the recirc through the line? Hence, the line would be opened only to allow enough flow through to make up any difference between system flow and pump min flow requirements...right?