Generally speaking, if they are operated as the manufacturer intends, no. Soot occurs when the flames are impinged by a misplaced log or if the unit is not cleaned regularly. In addition, we have learned that burning scented candles in the same room as the appliance will cause the candles to generate an excessive amount of soot. The reason for this is that the scent is usually made from an alcohol-based distillate and, when mixed with the warm moist heat that the vent-free appliance provides, the candles will soot more than normal.
American Hearth and Home
1905 Boulevard
Colonial Heights,
VA
23834