Re: [RE-wrenches] Grundfos SQ FLEX AC/DC auto switching

[Allan Sindelar]

Mark, Your message gave me pause, as I just last week specified this setup, so I checked into it with our Grundfos rep. He said he had never heard anything recommending against the flex in a pressure system. He said the SQF doesn't know the difference between 40 psi and 100' of head. At the end of the day the pump just stops. He did make a point of emphasizing the need for pressure relief valves, as the helical rotor models can overpressure a system. Could you check with your distributor about this and post the reason you're given, please? Allan Allan Sindelar Allan@positiveenergysolar.com NABCEP Certified Photovoltaic Installer EE98J Journeyman Electrician Positive Energy, Inc. 3201 Calle Marie Santa Fe, New Mexico 87507 505 424-1112 www.positiveenergysolar.com Mark Dickson wrote: Our Grundfos pump distributor has always warned against using the SQF pumps in pressure pumping situations.  I can’t quite remember why, but you may want to check into that.  The Lorentz HR’s have been the choice in these situations.   Best regards,   Mark Dickson, NABCEP Certified Solar PV Installer ™ Oasis Montana Inc.     From: re-wrenches-boun...@lists.re-wrenches.org [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Kent Osterberg Sent: Thursday, May 20, 2010 5:18 PM To: RE-wrenches Subject: Re: [RE-wrenches] Grundfos SQ FLEX AC/DC auto switching   Kirpal, None of the SQFlex equipment is UL listed.  You may find that your AHJ won't approve any of the SQFlex controls and possibly not even the pump. Kent Osterberg Blue Mountain Solar Kirpal Khalsa wrote: Hi Folks.....I am working on putting together a domestic water pumping system using a grundfos 11 - SQF - 2.  This system will be connected to a standard pressure tank and cistern and have a solar array providing primary power.  However at night and on cloudy days we would like the system to switch back over to AC power from the grid.  I know that the grundfos IO 101 switch box allows the pump to use an AC source and when the AC source is removed it automatically switches back to DC.  What I am looking for is when the DC source (solar) is not available it automatically switches over to AC power (grid) ( the reverse of what the IO 101 switch does)  and when the DC becomes available again it again automatically switches back to the DC power (solar).  Has anyone done this?  Any recommendations for configuring this set up.  We are looking to provide solar water pumping during the day both when grid is present and when their is a power outage and AC pumping at night or cloudy weather all without battery back up. Thanks in advance for any advice.! -- Sunny Regards, Kirpal Khalsa NABCEP Certified Solar PV Installer Renewable Energy Systems www.oregonsolarworks.com 541-218-0201 m 541-592-3958 o   _______________________________________________ List sponsored by Home Power magazine List Address: RE-wrenches@lists.re-wrenches.org Options & settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org List rules & etiquette: www.re-wrenches.org/etiquette.htm Check out participant bios: www.members.re-wrenches.org

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