Vent-free gas logs can be used in an existing fireplace or a vent free firebox.  If you are looking for a log set than can add a considerable amount of heat for your room, then vent-free is the answer.  Vent-free logs are used with chimney damper closed.  Due to this the heat from a vent free log set is much greater than the heat from a vented log set.  Vent-free logs come in a variety of sizes and styles.  These logs can be run on manual control or with a remote.