I’ve had good experience with installing a five or 10 second delay on one of the pumps. This way the pumps’ start-current spikes are staggered
On Thu, May 8, 2025 at 12:38 PM Jason Szumlanski via RE-wrenches < [email protected]> wrote: > Water pump is not my strong suit. I usually leave that up to the experts > around here. Unfortunately, the experts are clueless when it comes to > off-grid living. I have a client with a setup that is pretty unworkable. > I'm trying to give him some general guidance. > > The setup uses a brackish water (might as well be salt water) very shallow > well. It is about 3 ft underground for the water table. The RO system > installer has a 1 HP 1.25 SF Century centrifugal surface pump drawing water > from the well and pressurizing the inlet of a StaRite 1.25 HP booster pump > designed for about 10 GPM at 150 PSI to run water through the RO system. > > Both of the pumps run simultaneously and continuously when producing > water, and the water production is ridiculously low. I understand that RO > production is going to be slow, but the amount of power these pumps are > using is pure insanity. I have advised the client that, at a minimum, this > system needs to be on a smart load circuit to run only when there is > adequate battery capacity. The startup surgery is not a concern, but it > does flicker the lights and it makes quite the racket. > > My thoughts are that the well pump is drastically oversized. The booster > pump only needs 10 gallons per minute, and it has a suction head of 15 ft. > I don't even know if the well pump pressurizing the booster pump inlet is > required. I'm thinking we should be slow pumping water into an interim > holding tank at least at the height of the booster pump. At a minimum, the > well pump should be on a pressure switch with pressure tank so it can > cycle. > > Can anyone give me some general guidance, and perhaps a VFD pump that does > not have the startup surge and is maybe more efficient? During times of > heavy use, the RO system can easily eat up half of the PV produced during a > day at this site. > > > Jason Szumlanski > Florida Solar Design Group > _______________________________________________ > List sponsored by Redwood Alliance > > Pay optional member dues here: http://re-wrenches.org > > List Address: [email protected] > > Change listserver email address & settings: > http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org > > There are two list archives for searching. When one doesn't work, try the > other: > https://www.mail-archive.com/[email protected]/ > http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org > > List rules & etiquette: > http://www.re-wrenches.org/etiquette.htm > > Check out or update participant bios: > http://www.members.re-wrenches.org > >
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