Was there an insert in this fireplace?

[gthomas785]

The bricks in my fireplace are stained black but the staining ends at a very straight boundary near the front of the fireplace. See the picture to understand what I'm talking about.

My theory is that there used to be an insert "slammed" into the fireplace which was later removed. The line would be where the surround met with the bricks. Any other thoughts on what might cause this?

 

[turbocruiser]

My guess is not an insert actually but doors (or perhaps a wire spark screeen) which were removed. I've seen several types of doors that are designed to seal the space and make it more efficient. I've also seen several types of wire spark screens to help reduce the risk of sparks jumping out of the fireplace. My guess is someone had something like that mounted to the edge and eventually removed it for whatever reason. The other reason my guess is this guess is because an insert shouldn't smoke externally so as to do that with the bricks at all. Lastly, if it was an insert in there at any time in the past, the original baffle of the fireplace would be missing or altered and there should be some placard somewhere that states the original fireplace was altered to accommodate the insert. Hope that helps.