Hi Ron, What you describe with using a pressure switch and pressure tank, and just running the pump with 240 VAC, is fine. You don't need the CU-200 to do any of that, if all you are doing is switching AC. The diagnostics is nice, but probably not worth the cost in this kind of simple setup.
One issue though. The SQFlex pumps are not exactly instant-on. There is a slight delay between when power is applied and the pump starts. Just make sure that you use a large enough pressure tank to keep the pressure from dropping too far before the pump starts filling it. You may have to raise the starting pressure on the switch a little above where you set the minimum pressure, to let it fall some at startup. When it becomes time to replace the pump (hopefully many years from now), I would just go with a Grundfos SQ straight AC pump instead of the Flex model. If you are not going to be using a PV-direct arrangement, there is not much advantage in using the Flex pumps. Brian Teitelbaum AEE solar -----Original Message----- From: RE-wrenches [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Ron @ earthRight Solar Sent: Monday, October 20, 2014 6:21 PM To: RE-wrenches Subject: [RE-wrenches] Grundfos SQFlex Hello water pumping Wrenches, I have a customer who has a Grundfos SQFlex 11 pump and he is getting connected to the grid. He will still have his battery back up charged by PV and wants to look at the most efficient way to operate the pump. It seems to me that neither the IO101 or the CU200 really is needed and he could just wire directly to the inverter output at 240v via a pressure switch on a standard pressure tank for most efficient operation. Although this doesn't give any access to the Grundfos built in diagnostics that display on the CU200. Would you recommend keeping a CU200 in the system or is it overkill? With the CU200 the max voltage is 120 whereas without it I can go with 240v and a more efficient operation. unless I am missing something. Ron Young _______________________________________________ List sponsored by Redwood Alliance List Address: RE-wrenches@lists.re-wrenches.org Change listserver email address & settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.htm l List rules & etiquette: www.re-wrenches.org/etiquette.htm Check out or update participant bios: www.members.re-wrenches.org _______________________________________________ List sponsored by Redwood Alliance List Address: RE-wrenches@lists.re-wrenches.org Change listserver email address & settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.html List rules & etiquette: www.re-wrenches.org/etiquette.htm Check out or update participant bios: www.members.re-wrenches.org