Question: I'm looking at installing Vent free Gas Logs in my fireplace but heard that this set-up produces up to 6 gallons of moisture per day into the room. Is this possible? Have you any information regarding this? Answer: Depends on how much gas you burn. It is true that gas vent-free produce quite a bit of moisture into the room, but you should keep these points in mind: 1. vent free are only designed for a few hours use a day 2. Most homes can use a few gallons a day of extra moisture in the winter time. As long as you do not use the logs in an improper way, the moisture problem should not come into play.