Hi Jason What’s the actual water output from The RO? We had one at our house before I took it out and replaced the house water with rainwater catchment. 3 yrs and counting in the high desert. I couldn’t live with the 2-3 to 1 loss ratio.
A few options as I suspect the actual RO output is closer to 1-2 gpm. 1. Use a 1/3hp well pump into a large pressure tank with relatively low pressure switch. You might even get away with a small sump pump. The RO should t need but minimal input pressure 2. Assuming the RO system doesn’t need rhe 1.25hp pump ( i am assuming the RO goes into a tank and much then has a pressure pump to supply the house. If it doesn’t I would recommend installing said design) I’d install a smaller motor and pump head to better match the RO flow rate. You could look at getting a high efficiency DC pump or 3 phase with vfd. Sun pumps has such things. Jay > On 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 > _______________________________________________ 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
