I work for a HVAC firm and one piping arrangement that is always an issue is branch piping. A lot of situations dictate the water supply in the bullhead of a tee with the branches out of the runs and the return in both runs and returning through the bullhead. I have piped fin tube and other applications this way and never had a flow problem, but others in the firm claim that one circuit will get the flow with the other very little due to the turbulance of this arrangement.
A recent articule in CSE mag showed condenser water piping with this exact arrangement but the focus was on the unequal lengths of piping to each cooling tower after the tees. As these systems are open systems I'm not sure if this arrangement is only associated with closed systems.
Can anyone provide further information regarding this arrangement.