The number one complaint I see on this sub about ventless gas units is the massive amount of moisture it puts in the air. That said, my in-laws have a ventless gas stove in their rather large family room and everyone loves it. It's great to stand in front of and warm your rear after you just came in from the cold. They don't run it for long periods of time so between that and the large size of the room, the extra moisture has no apparent effect. Edit: In summary, I'd say it's great for point of use (warming your buns, power out for a day) but I wouldn't use one for primary heat. More on reddit.com

Sounds equivalent to running your stove burners More on reddit.com

I believe the biggest complication would be that of additional CO2 buildup. Your bigger concern should be future liability though. If your inspector advised against it, and you sell your house in the future, the buyers inspector may well also catch it and you may be forced to either correct it as condition of sale or credit them the cost of the retrofit. I expect that adding a fireplace will add value to the home, but without doing it correctly you’re risking throwing that value away at resale. If it were me, I’d direct vent now, as doing it now (even if it adds cost now) will be significantly cheaper than retrofitting it later. More on reddit.com

Your other reply is INSANE and oddly biased. I am well aware tat this response it too late for you; but posting a real life reply for the next folks searching. This guy actually said ventless is bad, vented is bad, and then went on to recommend some specific model without mentioning which it was. It's like a failed angry sales pitch. Main difference Is that ventless have nozzles and air balanced so that the flames are a lower temperature which is prettier (more orange/less blue) whereas ventless burn at a more efficient temperature which causes less orange/more blue flame. The flame color is much less obvious if the flames are going into firelogs and ventless can make pretty flames, just not at every heat setting (crank it up to high and it's 50/50 blue/orange) Ventless setups are perfectly fine; aside from a teeny bit lower efficiency it's hard to fault them. The only real issues are that their complexity commonly outweighs their values. Only note is that a ventless setup WITHOUT a blower will provide no heat to the room (this is mostly seen in new homes where the builder went cheap and skimped out on the $100 blower, which can be added on later). The other poster listed dozens of inaccuracies. Some of the more egregious are that ventless are incresingly banned. As actual fact one state has a ban (CA) but that's largely based on not wanting amateurs to add gas lines in urban areas themselves. Massachusetts actually removed their ban recently, as no studies proved issue with ventless. Next odd statement was about returns. Having previously worked in logistics for a home improvement supplier I assure you that returns are not more common on ventless setups. ON TO VENTLESS: The cons folks harp on about are: moisture added to the air as a product of combustion. This is absolutely the case HOWEVER there are two considerations - One is that the amount of moisture added is incredibly minimal when used in an open environment such as an apartment or a house. The second is that the colder it gets, the less moisture the air holds; so in the coldest areas folks like me have a humidifier to ADD humidity to the dry air produced by our furnaces. Carbon Monoxide / smoke / fumes etc. Combustion of natural gas is so incredibly efficient that you've seen gas ranges for 75 years without ever thinking "do i need to open a window to boil water on the stove?". You must remember that; in this litigious age - if someone could have sued for problems due to ventless fireplaces they would have and they wouldn't be available. I know that sounds like a weak defense but it's realistic. I was raised in a family that used a ventless fireplace regularly and can confirm that moisture isn't a realistic concern - only evidence I saw in a decade was slightly fogged single pane windows - that stopped when nicer insulated windows were installed. As fast as as fumes: there was a carbon monoxide detector a few feet away and we added a low-oxygen alarm just in case and neither ever alerted; even when someone fell asleep and the fireplace ran all night long. Smells are non-existent after the first use, same with a toaster or a stove. Today my home has a wood burning fireplace that we rarely use and I don't own any gas fireplace at all. I don't sell them, I don't hate them - I just felt the need to list some more realistic information than what was already out there since I lived with a ventless one for more than a decade, and have in-laws with a vented model I've sat in front of for many years. Good luck and beware of insane oddly biased answers here on reddit; remember that just because someone has an internet connected device; they're not necessarily someone that should be listened to (feel free to include myself in there if you wish). More on reddit.com