Digest for RE-wrenches at topica.com, issue 1090 [RE-wrenches]

[Steve Willey, Backwoods Solar]

Magnetically coupled circulation pumps lose their coupling to the rotor if
overdriven by too large a PV module. Also the magnetic coupling can
sometimes lose strength, particularly when exposed to very high temperatures
for a long time. Some loss of circulation problems can be solved by reducing
the PV voltage. Diagnose simply by using a smaller panel, or temporary
cardboard over 1 cell (no harm to this at 12 volts) or a series resistor. If
it cures the no-flow, the magnetic drive has been slipping.  Replace the
drive or go to a smaller panel as specified for the particular pump and
motor.
Steve Willey       steve at backwoodssolar.com
www.backwoodssolar.com
Backwoods Solar Electric Systems

----- Original Message -----
> Date: Sun, 13 Apr 2003 13:49:03 -0400
> From: "Tom Lane" <tom at ecs-solar.com>
> Subject: Re: AC circulator vs. PV driven DC [RE-wrenches]
> >
> 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]

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