Although a modern gas fireplace doesn’t produce any smoke or odor, it’s flames do create emissions.

• A direct vent fireplace Draws its air directly from outside and vents its emissions back out using the same two-part vent pipe, keeping radiant heat in the room and the emissions outside. No Chimney is required.
• A ventless (unvented or vent-free) fireplace draws its air from inside the home and directs heat and emissions back into the room. Ventless indoor units are tuned to burn extra clean and have a built-in oxygen sensor that automatically shuts the unit off if the room’s oxygen level dips below safe levels. The advantage of a ventless fireplace is that it can be installed anywhere in your home where a vent pipe might not fit.