galvanized Vertical "chimney" off-gassing

Can i use Galvanized duct for my vertical chimney next to the bell? or will it get too hot and off-gas. How hot do vertical chimneys usually get?

I think you are referring to the heat riser. The temperatures reached will not only melt and vaporize the zink, the steel will also melt or be seriously distorted in short order. Fire clay or refractory cement should be used. Search for threads with heat riser in the title.

HI; I used regular black stove pipe to come up out of the mass, then i used thin wall hvac pipe to go the res of the way out. The black pipe seems to run around 130 degrees or so as it is in the mass as well as near the bell , the thin wall pipe that is attached to that runs around 100 degrees or less. I do not believe these temps are hot enough to gas your galvanized pipe but if it did it would only be the first time it got hot, Make sure that you have plenty of ventilation and you will be fine. If the zink burns off it would be a one time event , not every time you lite your stove.

Kailo Kanadian : Welcome to permies, and a big Welcome from all your fellow members in the Rocket and Wood stoves Forum/Threads ! With a total membership of over 19,000
members from around the world, you can come here nearly 24 / 7 and find someone who wants to talk about what you want to talk about, they will have widely,even wildly
different viewpoints and will generally stretch your mind as they show you a different way to look at your situation !

In your case this is Still not big enough, please go to our Sister Site, 'richsoil.com' , and click on Rocket Mass Heaters R.M.H.s. This will take you to a series of R.M.H. videos
of builds made by professional instructors, or under their direction, watch them all, about the 6th one there is a video that shows you how to prepare your barrel for use by
burning off the paint and cleaning any gunk inside it! Included as part of the process is how to heat the 1st 6' of the stovepipe to change the chemical bond of the zinc with the
stove pipe, so that it is permanently bonded to the pipe, when the zinc coating changes from shiny to dull this entire process is finished ! The rest of the stove pipe, that is also
buried in the Cob will never get hot enough for any zinc outgassing to occur ! Hope this helps, and is timely !

Think like Fire, flow like a Gas, Don't be the Marshmallow ! As always, your questions, and comments are solicited, and are Welcome ! PYRO - Logically Big AL !

Thanks Thomas that was just the info i was looking for, with pics too!