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Bob Vila and the Vent-Free Gas Fireplace — A Sorry State of Affairs

Fireplaces Produce Exhaust Gases. If They're Not Vented Outdoors, You're Breathing Them.

A few days ago I ran across an article about gas fireplaces on Bob Vila’s website. Naturally, I wanted to read their take on vent-free gas fireplaces (sometimes called ventless, unvented, or just plain stupid). “Vent-free technology, once considered controversial, has now won wide acceptance,” wrote Merv Kaufman.

Wrong! Wrong! Wrong!

If I can go online and find a lot of people saying otherwise, there’s still controversy. For example, Building Science Corporation has a paper in which they wrote, Ventless gas fireplaces should never be installed.” Yes, it says ‘never.’

A company called Fireplace Creations by BMC, which sells gas fireplaces, writes on their website, After doing research, we decided we would never put a vent-free (room vented) appliance into our home. Because of this decision, we didn’t believe it would be right to sell them to our customers.

A fellow who calls himself The Gasman on writes, Choose a vented space heater or gas fireplace, and prove to our future generations that we have indeed learned something from our cave dwelling ancestors.” His article in the Choose a Space Heater section, is titled Is Choosing A Vent-Free Gas Fireplace Stupid or Foolish?… You Decide.

Sorry, Bob Vila, you’re wrong. There is definitely still controversy surrounding vent-free gas fireplaces. Now, I know you didn’t write the article yourself, Bob, but still, if it’s on your website, you’re endorsing this nonsense.

In a nutshell, the reason folks who understand building science oppose vent-free appliances is that:

  • Even when working perfectly, they put a lot of water vapor into the house. (See my recent article on combustion.)
  • Drafts, fans, candles, and tight houses can mess up the combustion process.
  • Many homeowners don’t understand how to operate or maintain them.

Yeah, they may have fancy technology built into them now (oxygen depletion sensors and catalytic converters), but the bottom line is that the risks can outweigh the benefits. It’s not that hard to build a chase and cut a hole to install a direct vent model, so why take that risk?

Still not sure? Read these letters from homeowners who suffered the consequences of having a vent-free gas fireplace in their home.

Come on now, Bob Vila. Prove that you’re not just a has-been by helping to turn vent-free gas appliances into has-beens. It’s fine to endorse products, but you’ll gain a lot more respect by coming out against products that have so many strikes against them.


Addendum: I just got reminded of another quote from the gas fireplace article on “Since no actual combustion occurs in gas fireplaces…” It came up in the comments below but seems so outrageous that it needed to be up here in the main article. It’s possible that this crazy statement is just a result of bad editing. Sadly, it’s also possible that whoever wrote it really doesn’t understand basic science and should not be writing about gas fireplaces at all.


Related Articles

A Ventless Gas Fireplace Is a Liability

3 Problems with Atmospheric Combustion Inside the Building Envelope

Unvented Natural Gas Space Heaters Should Be Removed


Photo of fire by Steve Paluch from, used under a Creative Commons license.

This Post Has 41 Comments

  1. There you go again, poking at
    There you go again, poking at big names just to get more attention. You media whore, you. Actually, I am just jealous that I didn’t pick up on this before you did. Good to call out Vila on these moronic devices. To me the fall into the category of “don’t kill your clients.” I was once called in to do a few hours of consulting on a very high end new house right before they started insulation. It had 5 Isokern masonry fireplaces, including 2 ventless ones. I suggested that they consider getting rid of them, but I don’t believe they did as I was not called back about the project. Hope they all survived.

  2. A few years ago a client
    A few years ago a client asked to have a non vented gas fireplace installed. I did some reading as it was a relatively new product and what i found I din’t like. I strongly suggested that they not install it and explained my reasoning. They insisted and had someone else install it.  
    I saw them years later as they wouldn’t do business with me since I didn’t do what they wanted and told me that the fireplace was a mistake and had taken it out. Ummh. I still don’t like them either.

  3. Curmudgeon
    Curmudgeon: I plead guilty. But I read and re-read the article several times to see if I left them anything to come after me for that I couldn’t defend.  
    Todd V.: It’s good to do your research and then hold fast to what’s right. It’s also nice to be told later by the client that fired you that you were right. 
    Chris K.: I almost mentioned the EdenPure scam but decided to stay focused on just this one topic. Here’s a direct link to your article: 
    EdenPure Heater Exaggerated Claims

  4. If I was called to audit,
    If I was called to audit, repair, or weatherize a home that had one of those things, the first line item in my report or proposal was “remove unvented gas heater” Usually at no charge. 

    This was not negotiable for us. We remove it, or you hire someone else. 

  5. Rob S.:
    Rob S.: Yep. Getting rid of ventless gas fireplaces is always a good move.

  6. Ventless are VERY popular in
    Ventless are VERY popular in new construction around here. Builders too cheap to install a real fireplace. I’d rather have the wall space, thank you very much…

  7. Nice post, a question I would
    Nice post, a question I would have is how is a gas oven and stovetop different (i.e. no-vent other than a range hood which may or may not be in use. Is it just a factor or overall BTU output and lower usage say than a fireplace? 
    Thanks for your thoughts.

  8. Bob: Yeah,
    Bob: Yeah, and some of those people who buy those homes might go back to their builder with complaints or, worse, lawsuits. 
    Steve E.: Great question! I wrote about gas ovens recently (link below), and the truth is that they can be very bad. Way too many of them produce unacceptable amounts of carbon monoxide. 
    Don’t Let the Turkey Get You Down! Carbon Monoxide alert

  9. One dirty little secret is
    One dirty little secret is that ASHRAE Standard 62.2 does not talk about these products because the industry was willing to block the standard rather than to have them banned. I know I was on the standard setting committee. 
    Here is what they had added to the scope:”2.3 This standard does not address unvented combustion 
    space heaters.” 
    One problem with them is the assumption that an oxygen depletion sensor will save you from CO. CO is generated at the exact point of combustion, generally it is not due to room oxygen being depleted.  
    Check this out 

  10. John P.:
    John P.: It is indeed unfortunate that ASHRAE 62.2, the residential ventilation standard, doesn’t address ventless gas appliances. The instruction manuals that come with the appliances reference other codes when discussing ventilation. One that I looked up today has a warning that reads: 
    If the area in which the heater may be operated does not meet the required volume for indoor combustion air, combustion and ventilation air shall be provided by one of the methods described in the National Fuel Gas Code, ANSI Z223.1/NFPA 54, the International Fuel Gas Code or applicable local codes. 
    Good point about the sensors! 
    Here’s a direct link to the article you referenced: 
    The Hearth, Patio & Barbecue Association (HPBA) Applauds Representative Cathy McMorris Rodgers’ Letter to Energy Secretary Steven Chu 


  11. From the article on Bob Vila
    From the article on Bob Vila’s site: “What has made them so is the technology and installation flexibility of gas-fueled models. Since no actual combustion occurs in gas fireplaces, zero-clearance installation is possible, …”  
    Since when is burning gas not combustion? 
    Serious mis-statement of fact, anyone? No wonder Bob thinks they are safe, he doesn’t understand basic physics, never mind building science.

  12. Lee:
    Lee: Thanks! I meant to mention that in my article and then forgot. That statement is so bizarre I can’t even figure out what they were trying to say. Maybe it’s a really bad editing job? I hope it’s not complete ignorance of what combustion is, but sadly, I can’t rule that out.

  13. Okay, we all know these are
    Okay, we all know these are bad, but what is the best type of “spot” or room only heating? Everyone hates to run whole house hvac when only one room is occupied.

  14. WOW! The worst part about
    WOW! The worst part about this is that he probably didn’t even write the article. One of his interns probably did and he signed it. 
    Nice jab there Curmudgeon! 
    Great catch Lee! DUH!

  15. Bruce L.:
    Bruce L.: Great question! I’ve added that to my list of topics to cover here. One answer would be mini-spit heat pumps for a more permanent installation. For portable heat, an electric strip heater would probably be the best option, though there are efficiency and safety issues with it. Unvented space heaters are a no-go.  
    The best answer is to improve the building envelope and have properly installed equipment that’s inside the envelope. We’re going to do that to our condo soon and install a hydronic furnace & tankless water heater, which will be much safer and more efficient than what we have now. In the end, that’ll result in much less energy use than dragging space heaters around the condo – an we’ll be less likely to burn the place down.

  16. Jon L.:
    Jon L.: Indeed, Bob Vila didn’t write or sign the article. In the byline, you’ll see the name Merv Kaufman, but it’s on, so his name is on the article indirectly.

  17. Vented range hoods? haha,
    Vented range hoods? haha, they haven’t been used for 20 years around here. Much easier install a recirculating model that doesn’t require ductwork. Modern house plans sometimes make it difficult to install ducts on range hoods. I would need to add a wall or use qty8 90degree turns to convert mine to vented.

  18. Bruce L.:
    Bruce L.: It’s best to mount heaters low because warm air rises. I haven’t heard of that company, but if it uses a fan, it’ll be less efficient than a passive electric heater. 
    Bob: Yeah, that’s certainly been the trend. I hope you don’t have a gas oven.

  19. So basically, I can get Bob
    So basically, I can get Bob Vila to endorse anything i have so long as I pay him enough money? 
    If only Oprah would return my calls and emails, I have this great T-shirt that if she could wear out in public. I tried Brad but he wouldn’t return my emails.

  20. Bruce wrote: 
    Bruce wrote: 
    > what is the best type of “spot” or room only heating? 
    I use a combination of an 80-watt floor mat at my desk and one of those oil-filled heaters that look like a radiator. I keep my house at 66 during the day while the wife is at work. The oil provides thermal mass, making it more efficient (and effective) than a heater with a fan.  
    For super-efficient homes with a mini-split heat pump (e.g., no auxiliary heat), I recommend the homeowner keep a couple of portable “radiator” type space heaters on hand for unusually cold days, and I typically specify electric floor heat for the baths (or a toe-kick heater).

  21. Great article. I’ve had one
    Great article. I’ve had one for 20 years. You can monitor for CO, & crack the windows. But- they put out micro-particulate which plates out on your mirrors and in your lungs. Never combust indoors, not even with a fireplace, except in a winter power emergency!

  22. The Bob Vila website has
    The Bob Vila website has become a content play to attract traffic from search engines and feed those visitors ads on the side. Probably hired a shwack of writers and gave them all a big list of topics to write about. The site editor may have more of an SEO (search engine optimization) background than a construction contractor background. 
    A trusted brand like Vila’s and the fact that many other large media sites link to it, and now this post does too, means the site and those hundreds of home product articles rank well in Google for a wide range of search phrases. Like many content farms- pumping out mass volumes of keyword rich content that attracts eyeballs is more important than content with truly reliable facts. 
    As well, pagenate those long articles so they span over 3, 4 or 5 pages to increase the number of page views and get those ads seen a few more times.

  23. Stever:
    Stever: That’s pretty much what I suspected. If it’s really true, it’s kinda sad that Bob Vila spent his career giving out lots of good home improvement advice and building a reputation, only to sell that reputation to and see it diminished.

  24. This is a deadly practice. A
    This is a deadly practice. A gas fireplace will never burn with a 100% efficiency and so the exhaust is a mixture of toxic smoke and un burned gas. Also from experience people tend to throw scaps of paper and cigarette butts at these fires, again causing poor combustion. Dont Do it!!

  25. I am interested in a ventless
    I am interested in a ventless insert for our fireplace. I checked out your website to understand concerns with these types of units, as much as the information was informative, most of of the consumer feedback on your site is many years old and I wonder if manufactures/various state government requirements have improved on these units?

  26. Marcus T.:
    Marcus T.: “Don’t do it” is right! 
    Katie: No, ventless gas appliances are still a bad idea. There’s no controversy about this among those who understand building science. Manufacturer or government requirements don’t change the fact that the combustion products stay in the house if the appliance isn’t vented.  

  27. I have a VENTED gas fireplace
    I have a VENTED gas fireplace. 
    There is no flue damper, and is therefore “open to the outside” all the time. 
    Unless it is actually running (burning gas), it is the coldest spot in the room, and doubtless raises my heating bill. 
    I’m not saying this to endorse ventless fireplaces… I wouldn’t have one of those either. 
    There used to be (maybe still is) AUTOMATIC flue dampers that figured out when there was a fire, and opened automatically, and then closed automatically when the fire was completely out. I never felt comfortable trusting it to open and close automatically. 
    Give me a fireplace with a flue damper that I can open when I’m using it and close when I’m not. 

  28. Glad I found this article. I
    Glad I found this article. I have been going back and forth on vented/non-vented for about a week. Since this is going into my basement, I’m still not sure how easy it will be to vent but I’m gonna find out!

  29. Ira: You
    Ira: You’ve pointed out another flaw with gas fireplaces, whether vented or not. I agree with you that I don’t want to have a damper that that I can’t close fully, or worse, as in your case, no damper at all. 
    Mike W: Glad we could help. Ventless gas fireplaces do not belong in homes. A basement would probably the worse place inside a home to put one, too, so I’m glad you’re going to find a way to vent it.

  30. You need at least one
    You need at least one dissenting voice on this site. Here goes: I am looking into buying an unvented gas heater for backup heat in my Vermont home. Two years ago we switched to wood as our primary heat and have used our vented gas heater as little as possible since. This saved us literally probably a little short of $10,000 over two winters. My wife wants a backup though. 
    Noting the objections to ventless heaters I have found on two or three websites, I am not very impressed. Water–> Mold? I run two humidifiers in the winter to put water back INTO the dry winter air. If I don’t, my throat is sore all winter and my guitars and violins dry out and sometimes crack. Bring on that humidity, we need it! Carbon monoxide? Detectors are available for $20 up. We have two nice expensive ones. I do run the kitchen oven some mornings while waiting for the wood stove to reach a useful heat. In this way I bring the house temp up by 5 or 6 degrees. Not a beep from the monoxide detectors. 
    Other dangerous poisonous chemicals in the gas: If this were a serious problem then many of us would have felt it by now when running our gas stoves and ovens, which are also vented into the house.  
    These issues seem to me to fall under the heading of “first world problems”, sort of like like the “heartbreak of psorisis.”  
    I have not bought the ventless backup yet, but am strongly considering it, it seems much like heating the up a bit house with my oven, only safer, what with the oxygen sensors, etc.  
    Higher efficiency in the use of hydrocarbons is a GOOD thing, Global warming worries me MUCH more than the problems you mention. 
    About Bob Vila I cannot comment, I do not watch TV.

  31. First this is a great site
    First this is a great site.This is the first article I’ve read here and I do intend to check it out more, and perhaps click a few ads.  
    Anyway, I found this article after researching a bill handed to my senior-citizen (only chronologically) parents after already having busted the installer of their new ducted nat. gas insert for trying to charge them $200 for a completely unnecessary chimney sweeping. It was already swept and not used since. Guy claimed it was caked with creosote. 
    Anyway, they went with ducted because the chimney was already there, but also because the place from which they bought the insert (best rep, longest in biz here) doesn’t sell the ductless and seems to have made it a practice to warn everyone passing through their door about them.  
    Ian: I understand your sentiment, but I don’t think this is a ‘first world problem.’ Breathing minute amounts of particulate matter might not affect many people negatively, if at all, no matter how long they are exposed. Others, it might take a decade or whatever. Some react very fast. Children are of particular concern.  
    Indeed, such interior pollution is a major health concern in both developed and developing countries. 
    As for psoriasis being a first-world problem? I dare you to tell me me that to my face, because my reaction might just affect yours. You obviously are an ignorant arse to make statements about medical conditions of which you know nothing. I bet you don’t believe in vaccinations either.

  32. OK, read the links and also
    OK, read the links and also read reviews on Amazon by people who bought unvented gas heaters and fireplaces and CO guages and detectors (yes there is a science of detecting and Measuring CO)and I think the people knocking gas stoves, gas burners, and other unvented gas fireplaces and heaters must be shills for the electric company and/or vented fireplace manufacturers and installers. I’ve spent 66 years living in houses and apartments where the gas stove burners and ovens ran for extended hours every day. No CO poisoning symptoms yet. Just spent 6 days without electric due to Sandy and the Nor’easter and ran simmering pots of water on the 4 burners of my gas range as the only source of heat. Presently looking into some sort of ventless gas source of emergency heat for when the next one hits. ANd I’ll buy one of those fancy CO and CO2 measuring devices to be safe. Thanks for an interesting topic.

  33. Hi 

    I have been using a ventless gas stove for over 12 years now and have never had any issues with the unit or health problems. At high heat it produces 33000 BTU which is more than enough to heat my 1700 square foot home most of the time. I also have it tied to a thermostat so that it cycles on and off depending on demand. 
    I do have several CO detectors, some as close as 5 feet from the stove and not once have they ever gone off.  
    The unit heats my whole story and a half home and moisture buildup has not been an issue.  
    Maybe it is because my home is 90 years old, has adequate air leakage due to plank sheathing etc.  
    The unit burns very clean. In fact I repainted the bright white ceiling after 10 years of use and I had a hard time telling where I was painting and what had been in place for 15 years. The only way I could tell was by the sheen of the paint. 
    If you have a very tight home, then the moisture and other issues may be a problem. But if an HRV is installed this should not be an issue either. 
    Besides the cats love to sleep in front of it on cold days and I do not have to mess with firewood, pellets etc. 
    Just my humble opinion.  

  34. Bob:
    Bob: Carbon monoxide poisoning happens at much lower levels than you may be aware of and sadly, the standard CO alarms you buy at the big box stores offer little to no real protection. If you’re interested in learning more, see my article, Don’t Compromise — Get a Low-Level Carbon Monoxide Monitor
    Rich: Ah, now there’s an interesting term: “adequate air leakage.” Air leakage isn’t the same thing as ventilation. Regarding ventless fireplaces, if you want to take the risk with your family, go right ahead. The law doesn’t prevent people from doing all stupid things.

  35. We have a vermont castings
    We have a vermont castings vent free (Radiance) gas stove which i placed in the family room fireplace (5′ feet tall, 6 feet wide). Burns a blue flame, and radiates a lot of heat. We kept the flue open for the first 30 or so hours of use, no odors what-so-ever. Condensation? We have whole house humidifiers on the 3 gas furnaces in this 7500 sqft house and run additional humidifiers in the master BR at night. I consider this aspect a myth. Anyone with a gas stove/heate in Orlando with problems… Oh, come on. As for “soot” , daaum, look at the flame silly. 
    … I’m reminded of the radon BS where the folks who measure also remediate. When i told these idiots that if you are on well water, venting your basement will not help the huge exposure in the shower, I think they went home and took a bath. I actually read somewhere on the web in one of these vent-free scare sites about the gas stove sucking in radon and releasing “nuclear radicals”. Really? I bet vent free stoves cause nut alergies in kids too. 
    It’s cold here in PA today, and our VC stove is burning clean, blue and hot. Nice. Much nicer and cleaner than the big-arse wood stove we took out. 
    We have gas, CO and smoke sensors throughout the house wired directly to the FD. 
    Use common sense.

  36. We have had a ventless
    We have had a ventless fireplace in our home for 7 years now. We have no problems at all and we love it .When Sandy hit Long Island our house was without electric for 9 days.We had no electric but we were very warm without it our kids would of been frozen. You all need common sense just install carbon dioxide detectors which should be installed anyway and maintain the unit.This ventless fierplace was the beat decision we have ever made. It has also save us $$ with the oil companies we have cut that bill in half.

  37. Come guys, Bob Vila has been
    Come guys, Bob Vila has been a has 
    been for a long time.


    bought a ventless gas fireplace and 
    become really sick,had to have oxygen for several days and still 
    not back to normal. bob Vila was  
    right.they are not for your home 
    they should be vented. 
    posted march 14 2014

  39. We had a gas ventless
    We had a gas ventless fireplace in our first home 7 years and another in or second home 15 years. Never had a problem with either one.

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