I'm in the process of designing and building a 2-tier system with a single pump, but I'm stumped about the best way to do the flow control and priming.
I like the idea of using a 3-way valve like this "any direction" one from McMaster:
However, I'm not sure exactly how it works. Ideally, I would plumb it to have the outflow of the pump coming into the valve and then I could open it one direction to bleed off and another direction to make it flow through. In theory, I like it because there's only one valve in the system to deal with, but I'm not 100% sure how those 3-way valves work. Has anyone tried this?
The second option that I like is to put a T on the outflow of the pump, put a ball valve inline and stopcock on the side of the T.
The final option would be to use a valve like the one at the top of this page that has a drain on the side.