Recently I repalced my 8 year old whisperflow 2hp pump with a hayward Ecostar. I am having issues with a vacuum breaker that is preventing proper flow.
Here is the setup.
Pool with elevated spa that spills into pool, and the equipment is about 15 feet higher than the pool, about 8 feet higher than spa.
on the lines to the pump, there is a Jandy check valve, it is functional, I dont lose prime.
on the return line, there is a vacuum breaker like the one in this video
In fact it looks identical to that solar application, we have no solar panels, but its the same valve
Issue is this.....when the pump primes, the pressure is high enough the vacuum breaker is closed. When pump RPMs drop this valve opens as the total pressure in the system is about 4
If I dont close this manually with duct tape etc, air gets in and the return line gets air and the flow is interrupted. I have to assume that the hydrostatic pressure in the return line after priming actually helps the pump with the pumping (much like a hose draining a fountain using gravity only). The air disrupts this and pump has issues. My only remedy is to crank the VSP to 27000 rpms which causes enough pressure to close the valve.
I have been told if I remove the valve, the column of water may cause issues with siphoning from a weak point in the return piping. So, what can I do? is there a valve that is normally closed and opens with a small amount of pressure drop as when the pump turns off ?