Black Iron and Copper in floor tubing

John B.

Does anyone know how long will black iron and copper tubing last in concrete in a in floor heating application.

hr

A real good question

So many factors come into play. Completely encased in the slab would be best. Often times, however, the tube gets pushed to the bottom of the pour. Here it will be effected by the soil type, ph, moisture content, ground movement, etc. Wall thickness play into the life span also.

In many areas fillers are added to the concrete mix. Fly ash is a very common additive. Fly ash from high sulfur coal may react, in moist conditions, with copper, I've read.

Of course cracking and movement of the slab would be tough on any rigid tube. The fluid inside the tube could effect the lifespan also. A neutral ph would provide the best life. Flow velocity, another factor.

That being said I have seen a number of 50 year plus copper and steel systems. Failures that I have uncovered have always been on the bottom plane where the tube contacts the earth, or cracks that have sheared due to poor base prep.

I see a bunch of plastic coated copper on the market these days. Fuel oil line material I suppose. If I were to consider a copper tube I would seek out a K grade, plastic coated material, be certain of the base compaction, elevate the tube on high chairs, quiz the batch plant about options for fillers, and cross your fingers!

I don't think I would consider steel,even with welded bends and connections. For all these reason PEX, at this point, still looks best for my money.

hot rod

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Dave Yates (PAH)

In my area

Most of the copper systems have long since failed. The black iron systems continue to chugg along because the BI and concrete have the same coefficient of expansion = no stress.

Next week I'm meeting with the owner of a BI system my firm installed in the 40's to see about cutting a new floor opening to accomodate an elevator. Fortunately we have detailed drawings showing the location of the piping. Should be an interesting dig and retro-fit re-routing piping job. Two floors of antique radiant to open.

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Dave_4

steel should last quite a while....

..they use it for hockey rinks, all welded pipe on chairs