Here they need to be enclosed by codeNot allowed here to encase steel chimney pipes except in a brick chimney. Codes. Else they almost always have to go outside or in non-used areas like attics. So you have to usually build a chimney around the steel in living areas, so it is simpler to just install a ceramic one. Unless the upper part of the steel goes through a non living space. Which is what I could do. See below.
Inside:
View attachment 270532
In the attic:
View attachment 270531
Both chimneys:
View attachment 270529