We had an old back to back fire place in the house when we bought it. One in the living one in the dining room it had a brick wall that keep them seperate. We decited to redo the dining room we tore out the wall that was in the middle I had a steel box made and we beat it into the hole.this wall is 3 foot thick easier said than done. LOL I have no idea what the BTU of these are we really put them in for looks but they will heat the house 1800sq. Got the rocks out of a stream in the northern part of the state. Here are some pics.