I dearly love a wood fire. But after heating our house with wood for nine years, back in the eighties, we were cured of ever actually having a wood fireplace again. Still miss it sometimes, but I don't miss the ashes, bark, bugs, smoke etc. Guess I'm getting old.

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By viable I mean workable, functional. A chimney sweep or a builder adept in chimneys will give you a report. Certainly enquire about a future gas fitting rather than logs if possible. I say this as a fireplace anywhere is delightful and, if downstairs, it could heat upstairs through the house, to a certain point too. If you look at the quality of the brick laying, you will see that its not meant to be a feature which is why it was rendered, but that is choice only. Certainly seal the bricks. Good luck and stay with it if you can. Everybody loves the romance of a fire.

Ah, I wouldn't think so. Photo B is the external side of the chimney, which would have originally been outside the house (the external wall). So i'm guessing your living room was added onto the house at a later stage. So it was never designed to be a double sided fireplace, like some are. And yes, it is a structural part of the chimney. By the way, your bedroom fireplace is a beautiful original mantle, I wouldn't touch it.