Ben and Judy's Sugarhouse in West Edmeston, NY had one of these at one time. I was there a few years ago for a Glen Goodrich tubing seminar. After the seminar we walked one of their sugarbushes. Mounted right at the back of a garage, behind the sugarhouse was a PVC contraption, likely 30' or so high. I asked what it was and they said they had used it as a releaser at one time. They explained it, but being so long ago I don't recall details. They did say that the vacuum would pull the sap up in the vertical tube and at some point it would get a slug of air in it, that let the sap all fall out into a barrel on the bottom. The barrel had a drain tube to drain the excess to a sap tank. Then the process would repeat. Sounded neat but sadly I din't even have vacuum at that time and didn't pay close enough attention to what Ben said.