Monessen Vent-free logs continue to be the sensible choice when looking for a supplemental heating source. The high efficiency burner requires no outside venting, so all the heat stays in your home. Why are they the best? The most common complaint about ventless or vent free gas products is that the fire they produce is typically unrealistic. This is where Monessen differs from all other brands. With the exclusive burner technology pushes the envelope when it comes to creating a realistic looking fire yet maintaining the ability to operate in a vent-less environment.