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BAB Member Posts: 118
I do not know about the wisdom on copper, or no copper, on returns, ... but I do know that any two unlike metals will always cause galvanic action (corrosion). Also the proximity of heat, or static electricity, or steam, or alkaline materials (concrete) will accelerate said galvanic action. If you must then I suggest the use of dielectric unions to isolate the unlike metals. Bromley


  • Daniel_3
    Daniel_3 Member Posts: 543

    Well, not really a surprise at all since it was just a matter of time before a little jolt on the wet return would cause that rotted iron to give. You can see the steam rising in the picture below the lowest horizontal. It's a good thing this happened at the end of the heating season for there's not that much money to do a complete new boiler install just yet. I can't wait to change all the piping below the water level to copper to avoid this in the future. Whoever did that weak wet return install used a combo of galvanized, copper, and iron; nice work, eh? I'm going to drain the boiler in a couple days keeping an eye on the leak. Maybe I can do a quick repair job, but I think I'll just wait until this summer when the new install will occur. I have learned boatloads of things concerning my heating system thanks to this website and all you guys who take the time to share your enjoyment of steam systems. Enjoy the pictures! The Lord bless you all!
  • Mike T., Swampeast MO
    Mike T., Swampeast MO Member Posts: 6,928

    I think it safe to say that those wet returns are shot!
  • Mark Hunt
    Mark Hunt Member Posts: 4,909

    Wire mesh would hold water better than that!

    Blessings back at ya'!!

    Mark H

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  • gerry gill
    gerry gill Member Posts: 3,078

    and when you put the copper wet returns in, you'll create a battery, and the insides of the boiler will someday look like those pipes..but the copper returns will look fine..

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  • Jim Bennett
    Jim Bennett Member Posts: 607
    Don No...

    if I buy that Gerry. One of the buildings I work in (a 500,000 sq ft industrial plant) Has ALL copper returns. (up to 6") Built in 1974. The returns that I have tapped all look great as does the Cleaver Brooks steam boiler. (tended to by a doting operating enginner)

    Jim Bennett
  • I don't buy it

    either . Probably 1/2 our steam accounts have some copper on the returns . The vast majority of our replacement steam boilers are still up and running when we change 'em out . 50 - 60 year old boilers are a common sight .

    I would like to know of any study that proves copper return pipes were the cause of premature boiler failures .
    Do any manufacturers specifically forbid the use of copper for return piping ? And personally , how can I check to see if I made a battery by using copper ? I'd like to test that on our next steamer ( hopefully this season ) .
  • gerry gill
    gerry gill Member Posts: 3,078
    sure seems to me

    that it would set up a cathode/anode relationship.

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  • Daniel_4
    Daniel_4 Member Posts: 5

    If I use iron again though it will still corrode fast but I guess the returns are better to rot than the boiler so who knows what's the best thing to do?
  • Larry Weingarten
    Larry Weingarten Member Posts: 3,286
    It's all a matter of...

    ... distance. The farther apart the different metals are, the less effect they can have on each other. Now if copper chips get rinsed back into the boiler, that's bad.

    Yours, Larry
  • Paul Fredricks_3
    Paul Fredricks_3 Member Posts: 1,557
    Yeah, but...

    What about every cast iron water boiler tied into baseboard radiators? And every steam boiler that has copper lines on the feeder, probably every one of them.
  • BAB
    BAB Member Posts: 118

    Galvanic corrosion is an electrochemical process in which one metal corrodes preferentially when it is in contact with a different type of metal and both metals are in an electrolyte.

    When two or more different sorts of metal come into contact in the presence of an electrolyte a galvanic couple is set up as different metals have different electrode potentials. The electrolyte provides a means for ion migration whereby metallic ions can move from the anode to the cathode. This leads to the anodic metal corroding more quickly than it otherwise would; the corrosion of the cathodic metal is retarded even to the point of stopping. The presence of electrolyte and a conducting path between the metals may cause corrosion where otherwise neither metal alone would have corroded.

    Even a single type of metal may corrode galvanically if the electrolyte varies in composition, forming a concentration cell.

    Metals (including alloys) can be arranged in a galvanic series representing the potential they develop in a given electrolyte against a standard reference electrode. The relative position of two metals on such a series gives a good indication of which metal is more likely to corrode more quickly. However, other factors such as water aeration and flow rate can influence the process markedly.

    Galvanic corrosion is of major interest to the marine industry. Galvanic series tables for seawater are commonplace due to the extensive use of metal in shipbuilding. It possible that corrosion of silver brazing in a salt water pipe caused a failure that lead to the USS Thresher sinking with all men lost.

    Preventing galvanic corrosion
    There are several ways of reducing and preventing this form of corrosion. One way is to electrically insulate the two metals from each other. Unless they are in electrical contact, there can be no galvanic couple set up. This can be done using plastic or another insulator to separate steel water pipes from copper-based fittings or by using a coat of grease to separate aluminium and steel parts. Use of absorbent washers that may retain fluid is often counter-productive.

    Another way is to keep the metals dry and/or shielded from ionic compounds (salts, acids, bases), for example by painting or encasing the protected metal in plastic or epoxy.

    It is also possible to choose metals that have similar potentials. The more closely matched the individual potentials, the lesser the potential difference and hence the lesser the galvanic current. Using the same metal for all construction is the most precise way of matching potentials.

    Electroplating or other plating can also be help. This tends to use more noble metals that resist corrosion better. Chrome, nickel, silver and gold can all be used.

    Cathodic protection uses one or more sacrificial anodes made of a metal which is more active than the protected metal. Metals commonly used for sacrificial anodes include zinc, magnesium, and aluminium. This is commonplace in hot water heaters. Failure to regularly replace sacrificial anodes in hot water heaters severely diminishes the life time of the tank. Water softeners tend to degrade these sacrificial anodes and tanks more quickly.

    Finally, an electrical power supply may be connected to oppose the corrosive galvanic current. (see Impressed-Current Cathodic Protection)

    all above cut & pasted from the internet
  • ttekushan_3
    ttekushan_3 Member Posts: 958

    Do you have any idea how many rolls of friction tape I have to use to repair a leak like that?!

    Its almost worth installing new pipe at this point.


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