I have this similar setup new for this year, running a 1/3 HP Procon 120GPH pump going through 6 of the 400GPD membranes in series. Got my motor from a soda fountain carbonator but burned up my original carbonator pump last year running it dry. Making sure this wasn’t repeated, I put a 3 GPM feed 12v pump (Amazon) before the Procon with a pressure switch - shutting off the Procon when feed pressure dropped below 5psi. I ran the feed pump on a variable power supply so I could dial it in to have about 15psi feeding the Prcon. I ran 110PSI on my needle valve and then had a recirculation line feeding back to the input of my Procon pump, with another valve controlling how much flow I fed my evaporator. I ran a 10ft copper line inside my exhaust stack as a preheater, so I could dial in exactly the flow I wanted out to achieve 150-200 degree feed for my pans and everything else would go to recirculation. I measured sap going in at about 38 GPH and concentrated 1.5% sap into 6% going into my boilers. I have the equivalent of 5 hotel pans for boiling, so I assume I was boiling off at 10 GPH. This system worked great after getting the kinks out (keeping the filter screen that was on the suction line cleaned after every 55 barrel and adding an extra cooing fan for the feed pump). I did not notice any degradation in RO performance from the start to the end of a 400 gallon boil. My setup was mounted in a plywood box I made that was lined with 3/4" Styrofoam with two doors that could be closed and a 25 watt light bulb on a freeze protection plug kept my system from freezing during the weekdays i was not there. I ran all 3/8" OD lines except for 1/4" permeate lines initially coming out of each membrane.https://photos.google.com/photo/AF1Q...mMOVBtrmlf4EX4