I put in a vent free fireplace with gas logs in the new house I just built. The salesman kept trying to talk me into it but I asked "how can a vent free fireplace work without an odor"? The logs are porcelain instead of ceramic and are set where the flames never touch them and sure enough, it has ho odor or smell of any kind and man, it cranks out the heat! My furnaces down stairs and upstairs barely turn on.