12 volt differential controller [RE-wrenches]

Mark Downing, Hurshtown Alt. Power solarman4 at yahoo.com
Sat Oct 18 14:54:47 PDT 2003


Darryl,

This particular job only, I am using a Laing pump which has actually been
discontinued.  Don't know the model number, but I bought a couple of them
from Bob-O maybe 6 years ago.  It draws less than 0.3A.  
The collector is a 30 tube Thermomax.  The glycol passes through the internal
heat exchanger in a 80 gallon tank and then through a 66 gallon exchange
tank.  Kind of a science project . . .
The water to be heated is delivered to the tanks via a 12V RV pump.  A
pressure tank is included so the pump doesn't spaz-out cycling off and on.
The power requirements for this system was very minimal before they
discovered showers.  This family of 10 was adequately supplied with power by
a single 40W module.  (This is an Amish household.)  Now that they use the
heated water for showers and the washing of clothes their PV needs have
grown.  I replaced the 40W module with a 100W last weekend.

Mark
--- Darryl Thayer <daryl_solar at yahoo.com> wrote:
> 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


__________________________________
Do you Yahoo!?
The New Yahoo! Shopping - with improved product search
http://shopping.yahoo.com

- - - -
To send a message: RE-wrenches at topica.com

Archive of previous messages: http://www.topica.com/lists/RE-wrenches/

List rules & etiquette: http://www.mrsharkey.com/wrenches/etiquete.htm

Check out participant bios: www.mrsharkey.com/wrenches/index.html

Hosted by Home Power magazine

Moderator: michael.welch at homepower.com
--^----------------------------------------------------------------
This email was sent to: michael.welch at homepower.com

EASY UNSUBSCRIBE click here: http://topica.com/u/?bz8Qcs.bz9JC9.bWljaGFl
Or send an email to: RE-wrenches-unsubscribe at topica.com

TOPICA - Start your own email discussion group. FREE!
http://www.topica.com/partner/tag02/create/index2.html
--^----------------------------------------------------------------





More information about the RE-wrenches mailing list