Posted by Tony Conner on February 09, 2000 at 05:19:39:
In Reply to: copper pipes for steam heat ? posted by steve d on February 08, 2000 at 20:35:34:
: the person putting in my new steam boiler wants to use copper pipe between the boiler and existing cast iron.including the hartford loop in copper.he is using 95/5 solder. someone told me that the joints will give in time because copper expands 50% more than cast iron.should I be concerned?
Copper does expand a lot more than steel for the same temperature increase. There are some copper applications in steam service, like air coils, etc. The big potential problem is with copper return lines. Condensate can (not nearly always, but can) pull copper off the pipe walls, and dump it back into your boiler, where it will plate out. If this happens, you get a galvanic cell set up that will pit your steel or iron boiler. The resulting corrosion can look a lot like oxygen pitting. It's important to realize that this doesn't nearly always happen, and that some systems have had copper returns for years with no problems. Copper, in and of itself, won't cause a problem. Some other factor has to occur at the same time. However, if you already have copper installed, half of the equation is already in place. Why take the chance? After material & labor are considered, how much money has been saved? Little if anything.
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