copper leaching in solar thermal system [RE-wrenches]

[Graham Owen]

Matt,

Is the heat exchanger double walled?  I am wondering if there is any
chance of the solar loop having higher internal pressure than the
potable loop?  Did you use clear non-toxic glycol (propylene) or the
regular toxic green stuff (ethylene) sold at automotive stores?  Has
there been any pressure drop in the glycol loop?  What size is the
copper pipe?  The flow rate needs to be less than 5 feet per second to
prevent corrosion.

The rarely-encountered copper corrosion problems are of five main types:
(1) aggressive, hard well waters that cause pitting (which contains
sulfates and chlorides, high total dissolved solids and a pH range of
7.3 - 7.8 or carbon dioxide at more than 10 parts per million); (2)
soft, acidic waters that do not allow a protective film to form inside
the copper tube; (3) system design or installation which results in
excessive water flow velocity or turbulence in the tube (burs left
behind at tube end cuts which upset the streamlined flow resulting in
localized high velocity and turbulence); (4) lapses in good workmanship
(too much flux which becomes polymerized) , and (5) aggressive soil
conditions (most natural soils do not attack copper but "cinders" in the
soil create acid when it becomes moist.

If the water source is the problem sometimes simple aeration is
treatment enough.

Graham Owen
GO Solar

- - - -
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

T O P I C A -- Register now to manage your mail!
http://www.topica.com/partner/tag02/register
==^================================================================