12 volt differential controller [RE-wrenches]

[Tom Lane, Energy Conservation Services]

TELL ME WHOSE SOLAR THERMAL COLLECTORS YOU ARE USING the total area and I
will list the parameters for the voltage and amperage required for two
different D.C. pumps  gator tom
----- Original Message ----- 
From: "Darryl Thayer" <daryl_solar at yahoo.com>
To: <RE-wrenches at topica.com>
Sent: Saturday, October 18, 2003 1:00 AM
Subject: Re: 12 volt differential controller [RE-wrenches]


> Hi Mark
> What is the pump and what size and type pump do you
> use?  How big is the SDHW, and what type.  I ask just
> for myself and other wrenches that normally do just
> 110 volt AC DHW.  I have a customer that wants both
> DHW and PV installed, so I am thinking of doing 2kW PV
> and to steal some DC for the SDHW.
> Daryl
>
> --- "Mark Downing, Hurshtown Alt. Power"
> <solarman4 at yahoo.com> wrote:
> > Yes I've thought of building my own, but not
> > designing it.
> > I was given a tip that Ivan Labs makes the
> > controller I need, and I am for
> > the time being going to see about getting one of
> > these.
> >
> > --- Darryl Thayer <daryl_solar at yahoo.com> wrote:
> > > Is not a differencial controller a comparator with
> > > hysterisis?  A Schmitt trigger?  That is a simple
> > > circuit to build, have you thought of building
> > your
> > > own?
> > > Daryl
> > >
> > > --- "Carl Emerson, Free Power Ltd."
> > > <freepower at freepower.co.nz> wrote:
> > > > Kurt,
> > > >
> > > > I would like to swap to this approach but I
> > suspect
> > > > that it would take
> > > > some time to optimize the threshold or
> > insolation
> > > > level that the pump
> > > > comes on at.... or do you not bother.
> > > >
> > > > Also the pump will continue to run when the
> > water is
> > > > fully up to
> > > > temperature unless there is a thermostat control
> > as
> > > > well.
> > > >
> > > > Maybe a combination of the two is needed and
> > would
> > > > be more efficient.
> > > >
> > > > Carl Emerson
> > > > Free Power Ltd.
> > > > Auckland. NZ
> > > >
> > > > sunwise wrote:
> > > >
> > > > >Greetings Mark,
> > > > >
> > > > >I'm not going to be much help regarding the 12
> > volt
> > > > controller but I
> > > > >will mention a trend I see in the industry that
> > > > does away with
> > > > >differential controllers completely.  Instead
> > of
> > > > using such a
> > > > >controller, a small (20 watt) solar panel is
> > wired
> > > > directly to a 12 volt
> > > > >circulating pump (typically a Hartel HEH10).
> > When
> > > > the sun is shinning
> > > > >on the flat-plate collectors it is also on the
> > pump
> > > > panel, etc.  These
> > > > >systems work great, especially in off-grid
> > homes.
> > > > >
> > > > >Kurt Nelson
> >
> >
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