AC circulator vs. PV driven DC [RE-wrenches]

[Tom Lane, Energy Conservation Services]

Reply. your observations are correct. However do not use more than a 30 watt
module with this pump. average run time is about 4.5 hours per day and only
about 2 to 3 hours at full speed in   the US 12 to 16 years is about the
life expentcy of  Hartell, March, and Ivan lab pumps.
Ivan labs has an EL SID 20 PV that is designed for 30 to 40 watt modules. It
is critical to keep the pressure drop low and not to use more 80 to 120 sq
feet with a single pump. Pressure drops through heat exchangers must be low.
gator Tom.
----- Original Message -----
From: "Todd Cory, Mt. Shasta Energy Services" <toddcory at finestplanet.com>
To: <RE-wrenches at topica.com>
Sent: Sunday, April 13, 2003 12:57 PM
Subject: Re: AC circulator vs. PV driven DC [RE-wrenches]


> The Hartell brushless DC motors are rated at 30,000 hours. Their brush
version
> is rated at 7000 hours. 30K is basically the bearing life... and when  run
for a
> yearly average of 5 hours a day = about 16 years... long time.
>
> Todd
>
>
> "Tom Lane, Energy Conservation Services" wrote:
>
> > DC pumps require precise matching of the amperage voltage curve of the
PV
> > module curve to the real motor requirements of the  DC  motor --the
reason
> > you are having problems is that you do not know how to match  THE  pv
module
> > to the DC  motor--the march WILL last 15 years PLUS   if the pv module
is
> > not over 16 volts AND the amperage is not over 1,4 amps -- the brushes
will
> > ride on an air  if you over power the 12 volt motor   gator tomGlobal
> > Resource Options" <jeff at globalresourceoptions.com>
> > To: <RE-wrenches at topica.com>
> > Sent: Wednesday, April 09, 2003 10:08 PM
> > Subject: RE: AC circulator vs. PV driven DC [RE-wrenches]
> >
> > > Peter,
> > >
> > > If we had great DC pumps, I *might* go along with the DC
recommendations
> > in
> > > this climate, but probably not.
> > >
> > > We've gone almost totally away from the DC pumps. Either too small
(ElSid
> > > 10) or too noisy (Hartell), or too much maintenance (March). Perhaps
the
> > > Dankoff are better, but they are still brushed pumps, and at 12V, do
not
> > > have great brush life. And who needs to remember to get the brushes
> > replaced
> > > BEFORE the collector stagnates?
> > >
> > > Yes, AC grid failure can result in a problem with an AC powered pump
> > running
> > > off an AC powered diff temp controller. Guess we've found that to be
less
> > of
> > > a problem than the DC pump non-power, PV panel covered by snow, PV
panel
> > > clear/solar thermal collector covered by snow, flat plate panel
running at
> > > low startup temps while full sun is on the PV, etc. problems.
> > >
> > > Certainly for a larger system, getting enough DC pumping will be a
> > > challenge, unless the tank and pumps are right at the collectors. This
> > will
> > > result in a "small plethora" of DC pumps and PV's. Just seems simpler
to
> > put
> > > in an AC pump. And then when the unskilled plumber goes to "fix" it in
5
> > > years, he'll have a clue. (Not an unimportant consideration.)
> > >
> > > Enjoy spring!?
> > >
> > > Jeff
> > >
> > > -----Original Message-----
> > > From: Peter Talmage [mailto:ptalmage at yahoo.com]
> > > Sent: Wednesday, April 09, 2003 6:15 PM
> > > To: RE-wrenches at topica.com
> > > Subject: AC circulator vs. PV driven DC [RE-wrenches]
> > >
> > >
> > >
> > > I am designing a solar heating system which will use
> > > 10  4'x10'collectors. I had planned to use a single AC
> > > pump operated by a differential controller. The system
> > > uses antifreeze so there is only modest head to
> > > overcome. My customer likes the reliability of a DC
> > > pump driven by a PV. I usually do this with small
> > > systems, but this one would need 4 Hartell pumps to
> > > get adequate flow, considering head loss. Anyone have
> > > any thoughts ?  Thanks.
> > >
> > > Peter
> > >
> > > __________________________________________________
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>
> --
> Todd Cory
> KE6SXS
> toddcory at finestplanet.com
> Mt. Shasta Energy Services
> License C-10 # 811428
> P.O. Box 689
> Mt. Shasta, CA. 96067
> (530) 926-1079
>
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