Having been down this rabbit warren, where I got to was that in general, the right answer is to take all the chimney breasts out, and the chimney up top if you can, as they are a liability when they are unused, and a costly and somewhat frowned upon luxury when they are used as intended to burn wood or coal or gas. And in smaller houses they take up space, that you need. If you want the cozy feels, burn bio eth that requires no flue.
If you really want to use them or like the aesthetic they really should be lined, but this is costly and messy work. At minimum a fireplace company or chimney sweep can test them for integrity but they will always suggest getting them lined.
Having been down this rabbit warren, where I got to was that in general, the right answer is to take all the chimney breasts out, and the chimney up top if you can, as they are a liability when they are unused, and a costly and somewhat frowned upon luxury when they are used as intended to burn wood or coal or gas. And in smaller houses they take up space, that you need. If you want the cozy feels, burn bio eth that requires no flue.
If you really want to use them or like the aesthetic they really should be lined, but this is costly and messy work. At minimum a fireplace company or chimney sweep can test them for integrity but they will always suggest getting them lined.