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Solar Water Heaters and Electrolysis

March 21, 2009

Hi,

My name is Adrian Chessman and I own a Solar Water Heating company in South Africa.

We recently installed 3 SWH on a commercial building and connected our copper piping from the system into galvanised piping which delivers hot water and feeds cold water to our system. The entire building has galvanised piping.

The owners of the building are worried about electrolysis causing corrosion and have asked that we find a way to avoid this. From what I understand, electrolysis will only occur if 3 things are present, 1) 2 different metals, 2) an electrolyte and 3) an electrical current.

My questions are therefore, if one of these elements is missing will electrolysis occur. Logically, no. And, if the connection between the copper and galvanised piping is interrupted by say a plastic fitting or short length of plastic piping, will electrolysis still take place. i.e. Do the two metals have to be in direct contact.

Any feed back on this would be greatly appreciated.

Adrian Chessman
Business Owner - South Africa

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Hi, Adrian. I would say there will be no electrolysis because there is no metallic path. For metal to electrolytically move from one place to another you need an ionic path (the liquid) through which the cations can migrate, and you need a metallic path through which the electrons can travel.

Regards,

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
March 22, 2009