A propane fireplace insert is a device that can be used to modify a conventional wood-burning fireplace to allow it to burn propane. Typically, a propane insert has artificial logs and a grate which propane flames burn around to simulate the appearance of burning wood.
There are direct-vent and ventless propane inserts. Direct-vent inserts draw in fresh air from outside and exhaust gases from combustion and water outdoors. Ventless inserts have a higher efficiency rating because heat is not lost in the exhaust process. They do, however, allow gases from combustion and water to stay inside a house. Some states ban the use of ventless propane fireplace inserts because of this.