Liners? Smooth wall? 306? 316?

[dvd1217]

Hi, I’m trying to figure what the best liner for given application and also best way to remedy the top of chimney.
What is better smooth wall flexible 316 ss vs just flexible 316 ss? Pre insulated vs insulation kit? 306 vs 316?
I have a 18 ft exterior fireplace.
Second I have my oil burner flue running up same chimney in separate flue than wood burning chimney but exits side by side than I have a slate covering. Any suggestions for installing? Do I need to remove slate and bricks? Then I would need to cover both the oil burner and fire place flues.

 

[Ctwoodtick]

You will want a med or heavy liner. 304 fine for wood. Stay away from liner that state they are “smooth wall”. That’s code word for thin liner with very thin inner wall that separates pretty easy and become a problem. Be sure to insulate any liner you choose.
Most med or heavy wall liners have a smooth interior anyhow.
The two flues should be a good few inches different in height to help keep exhaust from going down adjacent flue.

A new crown would be a good idea to and perhaps that could be covered with a cap designed to cover the area needed. Hers a pic of the cap I have for my 2 flues (I only use one for the wood insert).

 

[bholler]

Hi, I’m trying to figure what the best liner for given application and also best way to remedy the top of chimney.
What is better smooth wall flexible 316 ss vs just flexible 316 ss? Pre insulated vs insulation kit? 306 vs 316?
I have a 18 ft exterior fireplace.
Second I have my oil burner flue running up same chimney in separate flue than wood burning chimney but exits side by side than I have a slate covering. Any suggestions for installing? Do I need to remove slate and bricks? Then I would need to cover both the oil burner and fire place flues.

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304 is all you need for wood. Smooth Wall is good as long as it's midweight or heavy wall. The 2ply light wall stuff is junk. Pre insulated or insulated in the field is fine either way. And yes you will have to move the slate to install