I inspected a 2020 house today, and there was a gas only prefabricated fireplace with a built-in automatic lighting gas log located in an exterior patio. The patio had three walls and was covered by the same roof as the house. The top of the fireplace was just a metal sheet, no flew pipe or chimney. Is this allowed having in mind it’s somewhat exterior, was it required to have a flu pipe or chimney?
ventless gas fireplace…
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they put out quite a bit of heat…
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Yossi, I see unvented or ventless gas fireplaces all the time located in the interior of homes. Being on the exterior, it should have better air circulation if the open area is never closed off. I always recommend that they be operated according to the manufactures’ operating guidelines. With that in mind, certain jurisdictions may require all gas fueled fireplaces be vented to the exterior.
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Ventless fireplaces put out a lot of heat, but also a lot of fumes. As long as it remains an “exterior” fireplace they’ll be fine, but if they ever decide to close that wall off with a sliding glass door and or turn it into a 4 seasons room, then it could become an issue due to the fumes.
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I failed to mention that whenever I come across a ventless fireplace on the interior of a home, I also also recommend carbon monoxide detectors be installed in the same and adjacent rooms if they haven’t already been installed.
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Ventless gas fire log sets must be installed / positioned exactly per manufacturer’s instructions. Most log sets have metal instruction plates that have a diagram of log positioning. Improper installation of logs leads to soot and carbon monoxide being produced.
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Yeap, nuts to have in today’s tight construction unless it’s open to the outdoors like in the OP’s pic. Someone very clever decided to do away with a vent 
Inspected a $700k+ cabin last week and both internal fireplaces were ventless. Of course the nice outside deck fireplace was a wood burner. Makes you wonder doesn’t it? 
I just shake my head and move on. Never stop and wonder, it will kill you in the long-term.
Supposedly gas stoves will too. 16 years on cooking on it without ventilation and I ain’t dead yet. But if is proven that was the ultimate cause of my death, it will be addressed in my obituary… 
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my last two houses had ventless gas fireplaces, if the room is too small or confined You need to open a window slightly and they put off a lot of condenstion, the one I had in a three season room was too large for the area and a bit of a disappointment, The one i had in a large room was great and I miss having it. The vented gas fireplace I have in this house is nice to look at but that’s about it…
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That is what most manufactures suggest in their operation guidelines and why I recommend my clients to read them. I do give a brief detail on why they guidelines are recommended.
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The concern would be some future owner puts up a glass door, and creates a closed space.
The nitrogen dioxide (NO2) levels in the outdoor space are likely fine. Indoors? Meh. That’s like a really big gas cooktop.
Most recently, a study published last December found that 12.7 percent of childhood asthma cases in the U.S. can be attributed to gas stove use. (This result was found by essentially multiplying a measure of the previously reported risk of developing asthma from gas stove exposure by the proportion of children who live in housing with gas stoves.)
And yet our grandparents (at least mine anyway) cooked on a gas stove for 70 plus years and were fine. My granny died at 93 so I don’t think the stove did her in.
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Survivor bias alert.
If 50% of gas stove users literally died, and 50% were fine, you could still have a gas stove survivor at 93.
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