- Vented log sets are designed for externally vented fireplaces (chimneys) and operate more closely to a real wood fire, than do vent-free logs. Operating with the damper fully open on a wood-burning fireplace, vented gas logs can be used in either masonry with an open flu and chimney or a prefabricated firebox with vent pipe. Vented gas logs do produce heat but are not as efficient as vent-free logs and use more gas.
- Vent Free logs are very efficient, burning less gas because the damper is closed which keeps the heat in the room. However, vent free logs are not as realistic as vented gas logs. Vent free logs can be used in an existing masonry or prefabricated wood-burning fireplace with the damper closed.