Ventless gas logs, often referred to as vent free gas logs, are designed to be installed in wood burning fireplaces where the chimney and fireplace are in good enough condition to safely burn wood, or in a vent free firebox that has been tested and approved for use with aftermarket vent free gas logs. You CANNOT install a ventless gas log in a prefabricated metal fireplace that has not been tested and approved for ventless logs. If you have a factory built fireplace, please be sure to refer to your owners manual to make sure it has been approved and that you can meet all of the criteria necessary for a ventless gas log installation. Often times, a special heat reflective hood is required to divert heat from an overhanging mantel if one exists. It is important to make sure you are going to be safe and satisfied with your gas logs before you decide to buy a vent-free gas log set, so we suggest you talk with our experts or read these important articles below first.