Unlike other gas fireplaces that are vented, full combustion of the gas must be achieved so that byproducts from the burn can safely be emitted back into the living space. To accomplish that clean burn, the flame cannot impinge on the log set which would disrupt the combustion completion. The flame from the burner must pass between the logs and not interact with them. This does negatively affect the desire for the fire to look as much like a natural wood burning fire as possible. But, it is a sacrifice that has to be made to bring you the advantages that Vent-Free Fireplaces possess.