Galvanized or Black

[Ryedale]

After two years of EKO ownership but never installed.... and an almost selloff of the equipment and final decision to move from the original planned location (Basement) to a corner of my pole barn.....I am going forward with my boiler project, with a target completion of the end of Dec (it will more likely be into February with my busy schedule).

My questions are regarding piping.
I have a Ridgid 535 pipe threader and planning to do most of my piping in iron pipe. I can use either galvanized, or black iron. What are the arguments for or against each type.
I like copper but the price has gone through the roof, as I'm sure some here have experienced.

I'm using my original plan of a 1500 gallon Stainless Steel tank, and it will have copper heat exchangers (coiled type) which will be set up for summer solar hot water as well.
I'd like to do all the piping outside the boiler and to the tank in galvanized or black, but need to understand better about corrosion. A friend said stay away from black iron. but I see many commercial applications in black. One argument for black is that I'm surely going to be using some chemicals to keep corrosion down, afterall the whole EKO boiler is carbon steel, so black iron pipe would be no change.
Thanks for any input.
Andy

 

[Pat53]

I think galvanized is not something you want to use in heating systems. I have heard that it is harmful to certain components and circulators.

 

[pybyr]

Definitely avoid galvanized, given your copper heat exchangers.

Zinc (the galvanizing layer) and copper with fluid in between makes a primitive battery, which will exacerbate corrosion.

 

[Singed Eyebrows]

Sounds like your tank is non pressure so you do need the chemicals, mostly for your boiler. I like black iron piping as I'm old school. Try to get some quality piping because some of the stuff coming out of China won't take a good thread. Hopefully you use sulferized cutting oil with your threader. I have found 1 1/2" sprinkler pipe at the scrap yards that is like new inside & out, USA made. Good luck, Randy Don't use galvanized!

 

[RobC]

Andy I know this subject has been talked about a bit before so you may want to search old posts. Here are a couple articles on dissimilar metals. A real problem you may have is the copper coil immersed in the stainless tank. If you were to change from one kind of pipe to another you could use an isolator fitting that would keep the 2 dissimilar metals from touching. But that's different than immersion. I'm not an expert but I think you could corrode your coils. The solution may be as simple as hanging some Zinc in the tank so that is corroded before the copper ( sacrificial anode ). Again I would not know, would you wire ( bond ) the Zinc to the Copper coil or the Stainless. ( Copper I think ).
http://www.engineersedge.com/galvanic_capatability.htm
http://www.corrosionist.com/galvanic_corrosion_table.htm
Rob

 

[Ryedale]

This is all excellent information, Thanks for the link to the corrosion table. I'm studying this a little more.
By the sound of things the black iron pipe would be the very best option. I know that most water heaters have a sacraficial annode, so I think it's probably a good idea to include one in my tank as well, and possibly on the boiler side somewhere too.
Thanks again for all the feedback everyone.

Andy