Quote Originally Posted by wmick View Post
Yes and no.... It might use up some of the flow capacity of your pump, but it actually improves the vacuum level, or helps maintain it.
These little diaphragm pumps only seem to generate a decent vacuum when they actually have some liquid running through them.
(I'm guessing the tiny check valves need some liquid to seal them off.)
If they run dry, (even for a few seconds), the vacuum level drops way down... (this can happen easily, depending on number of taps and sap-flow conditions)
The bypass/recirc line ensures that some liquid will always be coming.. to give that vacuum its needed boost, when the trees dont flood it.
A needle valve on the bypass line will allow you to fine tune it. if you want.
Interesting. Thanks for the response. I'll have to give that some thought! Sounds like a great way to get a budget vacuum system going...