copper leaching in solar thermal system [RE-wrenches]

[matthew tritt]

Tom,

What you say is true, but. As a peripheral service to solar and wind stuff,
I do water treatment systems (ozonators, green sand filter, chemical
injection systems, softeners, etc.) in this part of the country. We seldom
see ph levels below 6.7, but often will encounter copper corrosion when
copper and other metals are connected in the same plumbing system. More
often than not, water softeners will be the culprit! Since softeners are
exchanging ions of salts for ions of calcium carbonate, it's often the
salinity and increased electrical conductivity that wastes the copper, not
the ph level. I have pulled sections of copper pipe out of houses which were
bleeding water through the pipe wall in areas of 7.2 ph levels. Also, many
homes will have a ground wire attached to the cold water inlet or some other
buried steel part of the water system. I believe that there might be some
connection between low levels of electrical current and damage to the copper
part of the system.

I persist in my observation that dielectric unions can (not guaranteed)
prevent many corrosion problems
inherent in plumbing systems with mixed steel and copper pipes in spite of
your experience in your lower ph part of the country. It could be that both
acidity and salinity can result in the same problem?

Matt
----- Original Message -----
From: "Tom Lane, Energy Conservation Services" <tom at ecs-solar.com>
To: <RE-wrenches at topica.com>
Sent: Sunday, October 20, 2002 8:44 AM
Subject: Re: copper leaching in solar thermal system [RE-wrenches]


> Matt
> Dielectric unions will effect metal connections but not water quality,
they
> aren't the cause of green water.  Copper corrodes often turn green when
> a) the ph is 6.5 or lower. ANSI/NSF standards require the water to be 6.5
or
> higher to use copper.
> b) there is too much dissolved oxygen or CO2 in the water with copper
pipes
>
> A city may meter sodium hydroxide into water at 5.1 ph to regulate the ph
> over 7.5, but local wells will still be 5.1 and corrode copper pipe.
Hanna
> Instruments at www.hannainst.com makes ph testers and CO2 and O2 testers
fir
> dissolved CO2 or O2.  Copper and Brass Development Ass. has excellent
> information and technicians to assist with copper problems.  They have two
> web sites - www.ccbda.org and www.copper.org.  You can send a water sample
> for water quality.
>
> Gaator Tom
>
>
> ----- Original Message -----
> From: "matthew tritt" <solarone at charter.net>
> To: <RE-wrenches at topica.com>
> Sent: Saturday, October 19, 2002 3:03 PM
> Subject: Re: copper leaching in solar thermal system [RE-wrenches]
>
>
> > Todd again,
> >
> > Di-electric incompatibility is what's happening. Electrolysis happens
when
> > dis-similar metals come in contact in or with a conductive media (hard
> > water?) and one of them loses! But you probably know this. Have you
water
> > checked for high TDS. I bet that's the culprit
> >
> > Matt
> > ----- Original Message -----
> > From: "Todd Cory, Mt. Shasta Energy Services"
<toddcory at finestplanet.com>
> > To: <RE-wrenches at topica.com>
> > Sent: Friday, October 18, 2002 10:35 PM
> > Subject: copper leaching in solar thermal system [RE-wrenches]
> >
> >
> > > I have a personal concern about my home's solar thermal system. Ever
> since
> > I
> > > put it in 5 years ago the hot water appears to be carrying large
amounts
> > of
> > > copper as is evident by the shower walls and floor (and my wife's
blond
> > > hair) turning a light shade of green. I am totally baffled by why this
> is
> > > happening.
> > >
> > > The system is a simple 2 flat plate, 2 pump, glycol system, all copper
> > with
> > > SS flat plate heat exchanger. I maintain the water heater's anode and
> just
> > > replaced the old one with a new magnesium one... so what would be
> causing
> > > the copper to be leaching from the pipes into the hot water?
> > >
> > > I rarely do solar thermal systems for others, but when I do I want to
> make
> > > sure they are configured so they will last. I worry that copper
leaching
> > > will eventually leave the pipes thin and prone to leaking. Anyone have
> > > experience with this situation or have a clue on what might be
> happening?
> > >
> > > Todd
> > >
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