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

[Kirpal Khalsa]

Hi All....thanks for the good feedback on this water pumping system.  Many
good ideas....It looks like this is a system which can be done.  I will be
looking for a relay that will have the necessary voltage characteristics
which will have ~200VDC on one side being normally closed and 240VAC on the
other side, normally open.
Mark, Allan.....I am looking at the Grundfos SQFlex Battery Back up system
brochure and it shows a SQFlex system running with a pressure tank in their
example system.  Additionally they brochure goes on to say that "the CU 200
Controller has terminals for a pressure switch, which will control the
pump's on/off  operation via the pressure in the storage tank.  The pressure
switch  should be of a normally open configuration, where the contacts
within the switch are in the open position when the pressure is below the
maximum set-point.  When the pressure in the system rises to the maximum
desired pressure, the contacts will close signaling the pump to shut off."
In researching further it looks like the float terminals in the CU 200
controller are able to be used for either a float switch or pressure switch.

I don't have any experience running a pressure tank in line with the output
of the system but I can't see why as Allan pointed out that it would know
the difference between 40PSI in a pressure tank or an additional 100' of
head.  I think that it is important to recognize the additional head ( due
to the pressure tank) that will be present and to take that into
consideration when sizing the array for the desired amount of gpm
production.
If anyone has any recommendations for a relay or other switch which can
handle 200VDC and 240VAC I would be grateful.....
Cheers,
-- 
Sunny Regards,
Kirpal Khalsa
NABCEP Certified Solar PV Installer
Renewable Energy Systems
www.oregonsolarworks.com
541-218-0201 m
541-592-3958 o

On Mon, May 24, 2010 at 2:42 PM, Mark Dickson <Mark at oasismontana.com> wrote:

>  Allan,
>
> This is all Dwight at Genpro could tell me. . .sorry to be vague!  I agree,
> it seems like it would not know the difference.
>
>
>
> I would love to shed some light, however this was shared with us at the
> NGWA show by a Grundfos Engineer.  It has brochursomething to do with the
> thrust load bearing on a them.  Lorentz has two I believe Grundfos has one.
>
>
>
> Best regards,
>
>
>
> Mark Dickson,
>
> NABCEP Certified Solar PV Installer ™
>
> Oasis Montana Inc.
>
>
>  ------------------------------
>
> *From:* re-wrenches-bounces at lists.re-wrenches.org [mailto:
> re-wrenches-bounces at lists.re-wrenches.org] *On Behalf Of *Allan Sindelar
> *Sent:* Monday, May 24, 2010 2:39 PM
>
> *To:* RE-wrenches
> *Subject:* Re: [RE-wrenches] Grundfos SQ FLEX AC/DC auto switching
>
>
>
> 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 at 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.
>
>
>
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