Modifying a fireplace surround

Question:  We have a floor to ceiling brick fireplace that we want to jazz up. I bought an antique mantel surround but it covers the register that is built into the brick. The vent blows hot air and is supposed to be turned on with a switch which we never use because it is too loud but even switched off, hot air still comes from the vent. Can we close up the vent safely?

Jake's Answer:  I don't like the idea of not covering up the opening in some way.  I would suggest you remove the vent cover and install brick in place of the vent cover.  If your fireplace is wood burning, the heat may damage the mantel.  There really is not any code reference on an issue such as this.  The building code does call for a minimum of 12" clearance from the edge of the fire box opening to the start of any combustible material.