Chimney height

[nissanneill]

Galvanising is only an alloy lead and tin. It is quite easily melted and then gone. Heat will bare the metal and rust (oxidation) set in. Look at the timn cans put into a campfire and how quickly they then rust.
It is rare that you should ever get flames coming from your oven and into your flue/chimney void let alone up your chimney.
A pot bellied stove has the chimney directly off the firebox and it often has fire in it and possibly burning the build up of resins/residue that builds up over time.

Neill

[Groves]

Let's not forget that the inhalation of the fumes from that galvanizing burning off will kill a person, too. Not immediately, but the symptoms of this "metal fume fever" will seem flu-like, until you die a few days later, of course.

Obviously, it takes a certain amount, but it never hurts to know what you're up against.