Chimney questions

robredneck said:

I have a Blaze King Princess installed in a manufactured home. It has double walled black pipe from the stove to below the ceiling support and Selkirk Metalbestos through the roof. I was told once you switch to the Metalbestos you have to continue that clear up to the cap because they don't make an adapter to switch back down to something else. I have found that single wall black pipe mates easily inside the Metalbestos. Is there a major safety concern doing the above roof chimney this way? Please let me know and explain in detail as I am new to this and trying to learn. Thank you.

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It's not because there isn't an adapter. It's because (like you were told) the Metalbestos or Class A chimney is required to run from the first penetration (wall or ceiling) all the way to the cap.
It's designed & rated to withstand both the exterior weather conditions & the hostile internal environment created by burning solid fuels (ie. wood).
It is also designed to reduce clearances to combustibles when it passes thru them.
From the stove to the Class A is called connector pipe. It's either single-wall or double-wall. That is the only place it is designed to be used.
If you were to run that outside, it would either rust away or deteriorate from the inside out creating a hazardous condition.