Gas log sets are available in both vented and vent free units. The myriad of choices of styles of logs, size of burner, features and functions or even an array of contemporary designs using glass media or even spheres all you to customize these units to your tastes. Vented log sets use your chimney’s flue to vent exhaust naturally. Vent free gas log sets require that the damper remain closed in your fireplace. This has the added benefit of keeping more heat in your home.