Copper gas appliance exhaust pipe

Hello all, I’ve encountered a first (for me) that I can’t locate any information on. In an older home I discovered a gas water heater with, what looks like, a section of copper exhaust. I couldn’t tell if it was copper or copper-colored. I did observe some scratches on the pipe which lead me to believe it’s copper. I was wondering; is this acceptable? I’ve never heard of copper being used for gas appliance exhaust. Thanks in advance for any input or references. - Tony

Homeowner special, not approved (but the seller says it worked like this for 100 years).


No can use for that!

Hey Simon, thanks for the info. Yeah, I saw a lot of that in this house.

Thanks Larry, is it because it’s susceptible to damage when it gets hot, i.e., it becomes malleable, or brittle?

That looks like copper downspout from an outdoor gutter system - hard to tell from the pictures but the elbow looks crimped and the pipe has a visible seam. In that cast that would be a hard no - not recommended by manufacturer.

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Don’t know the technicalities. But, like Simon said, it is not approved for that use, Anthony.


That is a first for me.

Just a tip. I carry a small magnet with me because sometimes piping material (water, drain or in your case exhaust) is not always easy to identify. I also use it for my records when I call out galvanized pipe. A magnet will not stick to non-ferrous material such as copper, aluminum or high grade stainless.


Hey guys, thanks for all the info. It’ll definitely be called out in the report. I need to start carrying a magnet thanks fro the tip, Brian.

Get one of these, very useful when you drop one of the dead front cover screws in a cluttered garage…

Not lighted, but twice as strong and half the price…

Tip: At 29.5 inches long, fashion a hook for the end and use it for lifting sump floats for testing! Nothing beats a tool that multitasks!


Sweet! Thanks for the tips!!