Hi, We are installing a Waterfurnace envision 5 ton system in an open loop configuration. I have a variable speed well pump and a return well. The installer stated that he would be putting a ball valve inline on the return side to control flow. This is where im not sure I trust these guys. It is a 2 stage that can flow as much as 15 gpm so I am assuming that it does not need maximum flow when in is in it's first stage. That would just be wasting electricity by over working the well pump. So my question is, how does this thing need to be plumbed on the return side. There must be some way to control the flow with a solenoid valve. ???