Correct flue pipe material - galvanized or black, and why it matters?

Al Roethlisberger

I had posted a photo of my boiler installation some time ago, and it showed the DIY circa 1991 install that used "black" stove pipe from the boiler to the chimney thimble.  At that time someone had commented that "black" stove pipe should have only been used for solid fuels and which suggested it was the wrong material for my gas fired boiler.



Well, doing some maintenance on the boiler recently, I noticed that the 15 year old flue pipe was getting pretty rusty in a few places and was likely to leak in a season or two, so thought it might be a good time to replace it.



With the former comment in mind, is it more appropriate to use galvanized, black, or "other" flue pipe on a gas fired boiler, or it is really a non-issue?



The following may be the right answer to my question though, which is from the Dunkirk PWB installation manual:



[quote]



Use a 28 gauge (minimum) galvanized pipe to

connect to the chimney.



[/quote]



So I guess I'll plan to run down some 7" galvanized flue pipe per the specs for the PWB8-D



But I was still curious why it "matters" what the flue material is made from.



Al

Al Roethlisberger

Stainless OK as an alternative, double or single wall?

BTW, would a stainless flue pipe replacement be a good alternative for low/no maintenance?



Also I see a lot of vendors are offering dual wall(insulated) versions of standard flue pipe which ostensibly increases flue draft, etc.   Anything to consider, and is this an appropriate option?



Thanks,

Al

Unknown

Al,,,,

it depends on your codes, and chimney type,, if I`ts NOT a condensing appliance,, but may condense in the chimney,,, you will ABSOLUTELY need a proper liner installed.



As to your "boiler to chimney" issue(in the basement),,,,, (depending on how deep your pockets are),,,, SS is by far the best,,,, but the heavier gage galvanized, or (painted black) will do you no harm,,,, but again, check  your local codes