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Letters From Vent-Free Gas Fireplace Owners
Page 5 - Letters 101+

Page 1 (Letters 1-25)     Page 2 (Letters 26 - 50)    Page 3 (Letters 51 - 75)    Page 4 (Letters 76 - 100)    Page 5 (Letters 101+)

SweepyIf you're considering a vent-free (aka ventless, unvented or room vented) gas stove or fireplace, you should first read these letters, excerpts and E-mail postings written by unhappy vent-free owners. We've corrected spelling and grammar where necessary, and edited out some of the harsher language from the original text.


#101: Vent-free owner reports possible link to brain tumors

Hello, I have a 22,000-39,000 BTU vent free natural gas fireplace and have been experiencing unexpected memory loss since I installed it about two years ago. It is in an approximately 340 sq ft room with two separate doors leading to the kitchen and the hall, which leads to three bedrooms. But at times I used to close both doors to the room and found it would heat the entire room at its lowest setting in 10-15 minutes or so. Anyway, in addition to the relatively sudden memory loss, I found I was often getting overcome by sleepiness (and thus taking naps, which I have never done) when reading in the room. I bought a carbon monoxide monitor about a year ago and plugged it into a wall socket in the room, but it has never emitted an alarm.

Any suggestions on what I might be able to do to test the air quality and test my own health? I am a mid-level executive in my company and have fairly regular health physicals, so I'm wondering if there are medical tests that can be run to detect levels of carbon monoxide in the blood.

I also have a slightly older brother who lived for two years or so in a small townhouse whose only source of heat was a vent free fireplace. While he was there, he began experiencing fatigue and memory loss and was diagnosed with a stage four brain tumor a year or so after moving out of the house. I have no evidence, but I have done a lot of research on the impact of decreased oxygen levels on the brain and resulting brain tumors, so I'm now beginning to wonder if there could be a connection between his tumor and the vent free heater.

Also, is there a way to vent the existing fireplace? It is installed in the middle of a living room on an inside wall. Can some type of vent be run through the wall and out through the attic? In the meantime, I will likely greatly cut back my use of the fireplace and lean more on the central gas heating system.

Thanks for your help. I'd also appreciate any other authoritative sources I could consult on the health impact of vent free natural gas fireplaces.

In Jesus and Mary,

Sweepy Hi David,

As noted in a previous letter, your Carbon Monoxide detector won't sound an alarm until emergency life-threatening levels of Carbon Monoxide (CO) are present. It won't detect Carbon Dioxide (CO2) at all. The issue on the table is the possible consequenses of exposure to levels of these gases that are below the imminent life-threatening threshold, but still high enough to adversely impact your health over time.

Lethargy and fatigue are symptoms of both CO and CO2 exposure, so that could explain your need to nap. Both gases also interfere with oxygen transfer to the brain, which is known to cause headaches, confusion and memory loss. Your own research has evidently found another link we weren't aware of, to brain tumors.

There are tests for CO and CO2 levels in the blood, but they're not part of an ordinary physical: you need to specifically request them.

Finally, Here is the only one way we know of to safely vent your vent-free:

Disconnect the gasline.

Take your vent-free outside.

Leave it there.


#102: Feels like her head is in a plastic bag

Q: We purchased our home in 1976. Nearly every year since, we have experienced flooding on our property, during which time we can't use our furnace and need an alternative source of heat. Our home was built with a wood burning fireplace, and we had a wood burning insert we used for years. My sinuses and allergies have deteriorated over those years, so we replaced the insert with a set of vent-free gas logs, which we had professionally installed. We have the damper closed and the chimney blocked, as per the manufacturer's instructions.

It is unbelievable how quickly the vent-free fire can change your breathing capacity. Frightening, actually. The moment the gas logs are lit I instantly feel like someone has put a plastic bag over my head. It is not a smell so much as a feeling. We only burn the logs as an alternate source of heat when we're flooded and cannot use our furnace, but the pilot light stayed lit most of the winter last year. Now I realize that these vent-free gas logs must be why I was ill all last winter. I first thought it may all be in my head, but then one day the control knob broke and the pilot light went out, and I began to feel better.

Because of the broken knob, we exchanged our original log set for a new set, also vent-free. As soon as my husband lit the new logs he experienced the plastic bag feeling too! I would go for a vented insert if I could be assured it would not affect us this way. They might cost more, but I do not want to feel like I'm dying and that is what I feel like when these logs are burning.

Thank you,
Carol Davis

Sweepy Hi Carol,

If you've read the letters above and followed the links at the bottom of the page, you've already learned that vent free fireplaces burn away the available oxygen in the room, and replace it with carbon monoxide, carbon dioxide, nitrogen dioxide and other gases. This depletes the oxygen supply, and your description of feeling like you have a plastic bag over your head certainly sounds like a reaction to oxygen deprivation!

Even the manufacturers themselves don't recommend vent-free products for people with allergies and sinus problems. Given the profound affect your vent-free logs have on you, I strongly urge you to make a change.

Vent-free inserts are designed to heat the room with their exhaust. Unblocking your chimney and opening the fireplace damper will siphon away the exhaust, which will make you breathe easier, but also take away the heat.

Since you really need backup heat in your situation, I recommend you replace the vent-free logs with a direct vent insert. These are sealed from the room, so they don't affect your oxygen supply: they get their combustion air down the chimney, and vent their exhaust out the chimney, leaving your house full of fresh air. The heat is delivered to the room via heat exchangers that are completely separate from the exhaust, so you get the heat without the poisonous fumes.


#103: Left the checkout line to check out vent-free safety

Wow! I haven't even finished reading your entire page of letters from vent-free owners yet, but I am already so excited to have stumbled across this information. My husband and I have literally been at the store with a vent-free natural gas fireplace in our cart and walked away from it because we disagreed about its safety.

A decade ago, I was an office manager for a home inspection company in Upstate NY. I was in charge of typing up reports for the field agents who inspected each house for compliance to state-mandated safety codes. One of those codes required that any appliance which had a combustible means of operation had to be (A) properly installed with proper clearance from flammable materials and (B) had to be adequately VENTED (usually a vent pipe running a certain distance above the roofline and away from living space windows).

My husband, who just recently left a job where he worked alongside HVAC guys, said it was his understanding that the only difference between a vented fireplace and a vent-free fireplace is a removable, nozzle-type end fitting that screws on/off the gas line. Why do people remain so ignorant to the hazards and risks of vent-free products?

I'm now 100% convinced that I am right, and will use your website as ammunition to support my stand AGAINST vent-free units. I will definitely be shopping for a direct vent system! Thank you for preventing a lot of heartache, both emotional and physical, and for helping to ensure the safety of me and my family.

Keep up the great work - knowledge is power!
Ronda R. in Ohio


#104: Hearth product shop uninstalling vent-frees in multiple situations

I actually work for a hearth products supplier/installer and have an installation crew at a job today uninstalling an unvented gas appliance. The customer put it in her home and cannot live with the smells she is getting. She tried using it but could not stand to have it operating. I am not nearly as knowledgeable as any of those making posts on this site, but have had customers want us to take them out in multiple situations.

As for heating, I would still love to see more info on the comparison between heating with gas furnaces vs. (vented) furnace-rated fireplaces.

Love your web-site.
Eric Spencer
[email protected]
The Fireplace Place, Inc.

Sweepy Hi Eric,
Thanks for the input, and for the kind words about our website! You can read one man's comparison between his forced-air furnace and his heater-rated gas fireplace right here in our Sweep's Library by clicking


#105: Hearth product retailer has replaced over 400 vent-frees

At this writing, our company has removed and replaced over 400 vent-frees with direct vents. We have many more customer who simply don't use their vent-frees, and tell us as soon as they save up the money they will have us replace them with direct vent models. The complaints are still the same:

Water running down windows and walls.
Soot all over home. EVEN IN THE REFRIGERATOR.
Yellow goo on walls and windows.
Headaches all the time when the fireplace is burning.
Children stay sick all winter [Doctor's advice: get rid of the vent-free fireplace].
House is full of mold & mildew.

Quote from a customer: " We were moving a bed from the north wall of our bed room. I could not believe it when we found a perfect outline of our headboard on our wall. ALL MOLD . Now we know why we were sick all the time. The man from the gas company told us it was from our vent-free logs. He said they cause sweat, especially on the north wall. "

Some good news: many of the largest builders in the US are now not allowing the use of vent-free products in their new homes.

More good news: there is currently a code change up for vote through the ICC INTERNATIONAL CODE COUNCIL [ FG47 ] to prohibit the use of vent-free [ROOM VENTED] fireplaces in all new site-built and manufactured homes that meet the air leakage requirements in section 402.5 of the ICC ENERGY CONSERVATION CODE. This would basically include all new construction.

In the meantime, why do we keep having these problems? We have great direct vent products now, many of them Heater Rated. Eliminate the doubt and stop the madness: CHOOSE A DIRECT VENT GAS PRODUCT.

Perry Bumpers
Fireplace Creations By BMC
[email protected]


#106: Never wants to live with a vent-free again

I lived briefly in a rented house with a natural gas vent-free heater. The foul odor and reduction in air quality was apparent even when only the pilot was lit, and much worse when the heater came on.

To alleviate the air quality problem, I placed a portable room air filtration device equipped with a Hepa filter, a fan and an ionizer near the heater. Typically I kept the air cleaner running on low speed to eliminate the odor from the pilot, and I would turn it up to a higher speed when the heater came on. The vent-free was in a 4 seasons room with french doors, so I was also able to close it off from the rest of the house when I wanted to.

The homeowner had installed the vent-free and claimed to have never noticed the odor when he and his wife lived there previously. According to him, they left the french doors open and used it in conjuction with the forced air gas furnace to heat the entire house. They have since moved back in, presumably for life, and now have a young child. I wonder what kind of health challenges they might eventually develop, as they use the 4 seasons room regularly. After living there through only one heating season, I would never want to live with an unvented fuel burning device again.

Thank you for your expertise and willingness to be the best overall source of information for home heating products I have found on the internet.

Very truly yours,
Rick Sparks


#107: South African Dealer won't sell vent-free "rubbish"

Bless you. We have been the only dealer for years in South Africa who refuses to sell vent free fireplaces because we have a conscience. We will use your site to convince as many clients as possible not to purchase this rubbish and use it to stop Architects from specing this unacceptable product. Yes they make money for the dealer, however there is more to life than money. Keep up the good work.

Wrex Trollope
Fireplace City
P.O. Box 1805, Durbanville
South Africa


#108: Vent-free Making us Sick

Is there an option for converting a vent free Monessen fireplace to a vented? The vent free makes us sick.

Pamela Owen

Sweepy Hi Pamela,
I'm not sure if Monessen fireplaces can be vented, but here's their contact information so you can check at the source:

Monessen Hearth Systems
149 Cleveland Drive
Paris, Kentucky 40361 Phone: 859-987-0740
Toll Free: 800-867-0454
Fax: 877-867-1875
E-mail: [email protected]


#109: What about our gas range?

Q: Hello, just came across your site, and am glad I did as I've been considering a Vent Free Fireplace or Heater. I read through a bunch of the Posts and they really are eye opening! Are there any Vent Free Heaters or Fireplace that don't kill you or your house?

Why don't Ovens and Cooktops put out Soot or CO, even on Turkey Day?

Thank you for your Reply.

Sweepy Hi Peter,

All vent-frees spew the same poisons into your breathing space: the only difference is the amount, which varies with the size of the burners.

The burners in ovens and cooktops are much smaller than the burners in vent-free fireplaces, and are tuned to burn blue, which is the cleanest, most efficient setting. Vent-free heaters and fireplaces can be de-tuned to burn somewhat "dirty" so they'll produce yellow flames to better simulate a wood fire. Yellow flames = more soot and more CO emissions.

Aside from the de-tuning issue, the main difference between unvented gas cooking appliances and vent-free gas heaters is the amount of daily exhaust exposure. A household gas range produces the exhaust from an average of 6,400 btu of gas per day (this average is computed on an annual usage rate, and includes the peak usage season during the Holidays). Even if you limit usage of your vent-free to the recommended three hours per day, in those three hours a 25,000 btu vent-free introduces nearly twelve times as much exhaust into your breathing space!

Another factor about cooking with gas: these days, most gas ranges are installed with exhaust vent hoods, and more and more states now require them for all new installations. When used with an exhaust hood, a household gas range causes zero daily exhaust exposure.


#110: Can I turn my vent-free into a direct vent?

I would appreciate your thoughts as to installing a direct vent on my vent free unit. My thought is to install one or two ports (3", 4" whatever would be the proper size) on the top of the stove; bring them into a Y 12' to 20" above the stove and vent to the exterior wall of the chase. Do you think it would be wise to drill two, three or more 1" holes in the lower part of the rear wall of the unit to bring in air other than room air? Maybe the front lower louvers should be blocked off so less room air is drawn in. The present unit is installed in a chase so it actually sits outside the room inside the chase. Hope to recieve your thoughts.

Thanks again,
Wayne Hunt

Sweepy Hi Wayne,

The short answer is, you're not going to be able to make your plan work. The intake and exhaust patterns in a direct vent fireplace are an enormously complex engineering feat, and require tightly sealed fireboxes, carefully designed intake and exhaust flow rate, combustion air preheat chambers and delivery ports that don't exist in your vent-free. There are many, many safety and performance considerations beyond that simplified overview, but the bottom line is, even trained professional engineers working from scratch (without the limitations presented by your existing vent-free firebox) don't come up with safe, functional direct vent designs every try.


#111: Does the color of the flame make a difference?

I am reading all the bad stuff on your website about vent free gas fireplaces and how sooty they are. It’s true. We have one and it’s horrible. If I buy a propane heater that has a blue flame will I get the same soot? I pasted a picture of it below. Thanks for the totally awesome website. I believe everything you say about those ventless gas fireplaces…they are crap! Will I be getting myself into the same trouble if I buy the heater below to work with my propane?

Thanks so much for your time, I really appreciate it more than you can know.


Vent-free LP heater

Sweepy Hi Gen,

We don't recognize that heater, and can't read the label, but maybe we can answer your question anyway. If it is vented, you won't have any more problems with sooting, excessive moisture or exhaust poisoning. If it is a vent-free, you'll be taking a step sideways.


#112: Add me to your list

Add me to your unhappy vent-free owner page. I moved into my house in September 2008, and turned on the pilot to my propane vent-free logs in November. I noticed immediately that the mantel was sooting horribly even when the logs aren't lit. We recently had a cold spell, and I lit logs..... what a mistake! There is soot everywhere, even on my upstairs toilet. My question is, do I have to take out the logs or can I just turn off the gas? My filters were black and I will not ever use these logs again, I have three small children.

Also, can I switch to vented? I do not have a chimney. Thanks


Sweepy Hi Terri,

Permanently turning off the gas will absolutely eliminate your sooting problem. So will switching to a vented fireplace, but if you do that you will have to supply venting. This doesn't mean you need a chimney, though: today's direct vent fireplaces just need a short pipe through any outside wall, with a cap on the outside.


#113: Legal Recourse for vent-free victims?

This is probably a silly question but is there not some legal action that can be taken in regards to the damage that vent-free gas fireplaces are causing? I also purchased one and my home is full of soot and I am getting headaches, this has been a cold winter and what a mess. I would appreciate any info that you can supply me with.

Thank you
Gail True

Sweepy Hi Gail,

Like yourself and most folks, we don't have the foggiest idea if damage from a vent-free is even actionable. It seems the vent-free manufacturers have gone to pretty extreme lengths to protect themselves in their literature: ie, Don't heat your house with the vent-free, Don't use it more than a couple of hours a day, Get it serviced every month, Always have a window open, Don't paint, recarpet or use any hairspray, candles or cleaning products, etc...

Why not give the family lawyer a jingle and get a professional legal opinion?


#114: Can Vent-Free be vented?

Currently have a see-through ventless fireplace which I do not use because of high oders, headaches etc. whenever I try to operate. Can I convert this unit to a vented unit or is it better to start with a new unit? I do have room to install a flue.

Thanks for your help,
Ray Bradshaw

Sweepy Hi Ray,

Only the manufacturer of your vent-free can tell you if it can be vented. Try a Google search and give them a shout. Even if your model allows this possiblility, you'd be far better off replacing it with a direct vent model. Once you vent a vent-free, you not only lose 90% or more of the heat produced by the fire, but also the heated air that gets drawn out of your house by the rising exhaust.


#115: Landlord puts Vent-Free in studio apartment

My landlord has installed a ventless gas heater in my studio apt. Any advice would be appreciated! I have not even turned it on for all the negative info I have read so far but they expect this to be my sole heating for the Winter.

Kim Amundsen (Kansas)

Sweepy Hi Kim,

You need to do a little research. Google the manufacturer and download an owner's manual for your model. We're betting you find your vent-free heater is not approved for installation in a sleeping room (studio apt), or as the sole source of heat for any apartment. If the landlord won't switch out the vent-free for a vented model, seek lodging elsewhere.


#116: How do we clean this sooty mess?

Hello- I have been reading the letters on your website regarding the problems with the vent free products. I too have been experiencing terrible sooting all throughout my house. My question is this- how do you clean the soot? Is there a special product, or procedure for getting the walls clean? Thanks.

Julie Demo
Rochester, New York

Sweepy Hi Julie,

We get this question so often we've published our response on its own page.


#117: Proper Ventilation for Vent Free?

I live in a condo in Florida that has a vent free fireplace with natural gas logs. I run the fireplace for less than 2 hours but smell a gas odor and experience headaches whenever the logs are on. I do not know of any way to convert the fireplace to a vented unit as there is no chimney. Does running the "fan only" setting on my A/C help ventilate the fumes or opening a window? In FL, fireplaces are more for ambience than for heating purposes. I love the look of a fire but do not wish to make myself or my family ill.


Sweepy Hi Terry,
Don't run your AC fan; it will spread poisonous exhaust (and soot, if your fireplace drifts out of adjustment) all over your house. If you must use the vent-free, open a nearby window all the way.


#118: Sneezing Black Mucous

I just found your site and it was such a relief. I bought an Empire brand vent-free propane stove for my new log home in 2006. I began using it that November, when it started getting cold here in Southern Illinois. For the first time in my life, I was besieged by sneezing atttacks, during which I expelled black mucous. I went back to the store and they told me to let the stove burn for a few days with windows open. That did not help. I suffered through repeated sneezing attacks, swollen and itchy eyes and headaches far worse than I had ever experienced. I used the stove throughout that Winter, and it turned everything in my house black, TV screens, computers, you name it. The air filters in the forced air furnace would turn black after about 30 days of use. I used the stove sparingly in 07 and 08, but it was bitter cold last month so I ran the stove quite a bit. Now I am so tired and listless, and my newly installed furnace filter is so black one cannot see thru it.

Do you know if any class action lawsuits have been filed in this issue?

Larry, in Ill.

Sweepy Hi Larry,
Still haven't heard of a class-action suit, and I'm a little surprised. When a small website like ours gets 118 letters (so far) complaining about vent-frees, it would seem to indicate some pretty widespread dissatisfaction. Why not pay a visit to a high-powered law firm and get the ball rolling yourself?


#119: Condensation Causes Mold, Sheetrock Damage

Another dissatisfied consumer….I wish I could return our vent-free fireplace to the company who sold it to us and stick it where the sun don’t shine. It has taken us since we built our new home in 2003 to figure out what was causing all the condensation on our windows in the Winter. When I say condensation, I mean water running down the window panes in waves….we have had to repair sheetrock around our windows several times and also deal with mold. I don’t know what health problems this has caused besides high blood pressure, but I can say it has almost caused a divorce. Now that we know the problem, we have contacted a lawyer…we may not get anywhere but we are certainly going to check it out. These products should be against the law.

Dennis Olivier
Silsbee, Texas


#120: Persistant Odor, Evidence of CO Poisoning

We're only wishing we had seen this website before installing a Superior vent-free fireplace in our new home. The fact sheet called it a truly safe, clean combustion, A.F.U.E. heater rated, 99.9% efficiency gas fireplace, equipped with back up safety features including built-in CO sensor and "Oxygen Depletion Sensor" system.

We always had a terrible odor when the fireplace was burning, and called the company we purchased it from to come back to look at it several times. Their technician made adjustments and at one time replaced the catalyst. Nothing seemed to make a difference, although they assured us it was safe to use.

My daughter was 1 year old at the time, and her cheeks would turn bright red. I now know that is a sign of carbon monoxide poisioning in small children.

About 6 years later we kept hearing a faint beeping sound from the fireplace. We replaced the battery but it still kept beeping. My husband called the company again, and was told that Superior had issued a bulletin in 2000 because the CO sensors were going bad in so many of these units, and the remedy was to remove it. He assured my husband it was only a backup safety feature and not needed.

Many years later, after starting the fireplace for the first time one season I ended up with heart palpitations and a terrible headache even with the windows open! When the EMT's came they tested the fireplace and immediately shut it down because of the high level of carbon monoxide.

We contacted the Consumer Product Safety Commission to file a report, and learned that there had been 33 other complaints filed on vent-free gas fireplaces between 98-08. They did not feel there were enough complaints to investigate further!

We also contacted Superior, who has since been bought out by Lennox. After much arguing they finally agreed to exchange our unit with a vented fireplace, but only if we paid for the installation and signed a release to keep them safe from any claims, lawsuits or damages. The release would also prevent us from disclosing any of the facts of the malfunction of the unit. Of course we did not sign!

We have not lit the fireplace since, but worry about future health problems for our children and ourselves from exposure to the vent-free poisons in our home for so many years. We can't understand how these fireplaces can be banned in many states and other countries, but continue to be sold in so many areas of the US today?

Karen Shaffer
Tecumseh, KS

Sweepy Hi Karen,
What we can't understand is that the Consumer Products Safety Commission claims they received only 33 complaints from 1998 to 2008, yet there are 110 complaints that we received in the same period of time right on this page!

Gentle readers, please continue to tell us of your vent-free experiences, but then submit a report to the Consumer Product Safety Commission, where it might do you the most good.


#121: Insurance Company won't cover vent-free sooting

My company was called in recently to remove a vent-free fireplace and replace it with a direct vent unit. The vent-free had sooted the entire house! It was horrible. The soot had found its way into their forced air heating system and circulated throughout the house. We could see the outlines of the studs and rafters in all of the interior rooms. Soot was everywhere, even inside the kitchen cabinets. Heaven knows how much the homeowners inhaled. As they were giving me the tour of damage to their home, they informed me that their insurance company refused to cover the damage. The wife said that as soon as she told them there was soot in the house from a vent-free fireplace, the insurance company said, "We don't cover that." I have heard of insurance companies refusing to cover damage from vent-free fireplaces throughout the years, but this was the first time that I had heard such a negative response from a company without even sending an adjustor to investigate. The insurance company was not a fly-by-night organization, but a major insurance company. I cannot say I blame them at all, but the lack of insurance coverage with vent-free products should definitely be considered before a homeowner buys one. They could be the ones holding the bag and paying for whatever damage might ensue.

Jeff Smith
Area Manager
Today's Fireplace and Outdoor Rooms, Inc.
Wilmington, NC

Sweepy Hi Jeff,
Thanks for sharing! Makes one wonder just how many sooting claims it might take to cause a major insurance company to adopt such a strict refusal-to-pay policy, doesn't it?


#122: Will adding a "fresh air plus kit" stop vent-free sooting?

Q: Need information on vent-free propane fresh air plus firebox and logset. Had a vent-free unit that sooted up entire house and now have a useless, but pretty, mantel. House is approx. 1800 sq. ft. very tight and well insulated. Can't vent outside due to it's being on inside wall - only place to put it. Can you help?

P.S. I was told that if I opened the window a crack, the soot would find it's way outside?

Nancy Wilson
Polk, OH

Sweepy Hi Nancy,
Your sooting problem occurred because the exhaust from all vent-frees, yours included, flows into the room, carrying the soot particals with it. It sounds like you've been told that adding a "fresh air plus" kit to a vent-free will alleviate that situation,
and that is not the case. The fresh air plus kit delivers outside air into the plenum surrounding the firebox, where it mingles with the already-polluted room air to "freshen" it a bit as it flows back into the room. The exhaust from the inner firebox, which is what caused your sooting problem, will continue to flow into the room unabated, just as it does now.


#123: Will opening the fireplace damper stop vent-free sooting?

THANK YOU for providing this site. I wish that we had been aware of it before we purchased our vent-free fireplace. We have been trying for years to figure out why our walls and ceilings have soot-like streaks. We have washed and repainted and, of course, the soot has returned. Now we have the answer as to the source of the streaks and why our efforts were futile, thanks to you.

Our vent-free sits in our original wood burning fireplace. In lieu of pulling it out and replacing it with a vented version could we just open the damper some to eliminate the problem or would we lose too much heat? Thank you for your help.

Patty Thies

Sweepy Hi Patty,
I don't know what configuration your vent-free fireplace might be. If it is indeed a fireplace, with its own enclosure, installed inside your existing fireplace, opening the fireplace damper probably won't do you much good. If what you have is a set of vent-free gas logs, with no barrier between the fire and the fireplace damper, by all means open the damper all the way whenever you have a fire; your chimney should evacuate all the exhaust.

The bad news: since vent-frees are designed to transmit virtually all the heat to the room via the exhaust, evacuating the exhaust will also evacuate most of the heat from the fire, along with much heated air from the room. A direct-vent gas insert, which is designed to lose the least amount of heat via the exhaust, would be a much better choice.


#124: Landlord Visits This Page, Removes Vent-Frees

Hi, I found your site while researching "danger of ventless gas heaters." My current landlord told me there was a gas fireplace in the apartment before I moved in. What he didn't tell me is it is ventless model, and that it is the only source of heat, save for another ventless gas heater installed in an upstairs bedroom (which has a manual that clearly states not to install it in a bedroom). Good grief! I posted the URL of your Vent-Free Letters Page to the building's yahoo group, where past postings revealed that every winter tenants had complained about the smell. My landlord and his wife saw my posting, and showed up soon after with electric radiant oil heaters, telling us not to use the vent-frees. I'm so glad I found your site and the links you shared.

Jen in Texas


#125: Can I Vent my Vent-Free?

How do I vent a vent-free system? Obviously not thrilled with the system, but don't want to spend the money to remove it.

I have a Temco ADL 36-2 that stinks up the house and we can't use it because we get headaches, etc. I simply want to vent the system and be done with it. It is on an exterior wall, so I have to think it is possible.


Sweepy Hi Eric,
A quick scan of
Temco's website didn't find mention of an outside vent option for the ADL 36-2, but you might want to contact the manufacturer to be sure.


#126: Fireman's Fiance Wants To Use Vent-Free: Should He Wear His Air Pack?

We bought a house that has a 32,000 btu vent-free propane fireplace in the basement. There is no other source of heat in our basement other than the fireplace (the rest of the house is electric baseboard). I am not a fan of anything gas powered other than my car, but my fiance wants to get the propane tanks filled and start using the fireplace. This situation is ready to send me over the edge... so I wanted to get your opinion on the matter (since you seem to be very smart and run a great website). My fears with a ventless propane burning fireplace center around the fact that it is burning something combustible, and the results get vented back into the room. I have been a firefighter for 17 years, and know for a fact that when something burns there are byproducts created (or else I wouldn't need to wear an air pack to go into a fire). Will this fireplace also create harmful byproducts from the combustion of propane? It is a newer fireplace and was professionally installed so it has the O2 sensor and everything... I just worry that we will be breathing in crap that we shouldn't. What do you think? Are vent-frees safe or should we put in electric baseboard heat like I want to??

David Fritz

Sweepy Hi David,
Your fears are not groundless: no matter what you burn, poisonous by-products are produced. Your oxygen depletion sensor, if it works properly, should shut your fireplace down before you keel over dead, but a growing number of scientists and medical professionals are concerned about repeated exposure to
below-lethal levels. On top of that, propane exhaust contains lots of other goodies like carbon monoxide and nitrogen dioxide. Have a look at the letters on this page, and follow the links at the bottom before you decide to start using the vent-free.


#127: Sooting in Rental Cabin: Typical?

We purchased a cabin six years ago and it has ventless fireplace logs in the main room. It is often rented and now our housekeeper tells us that there is black soot on the carpet of the loft, located above the fireplace, and that she has also found black soot on the upstairs bathroom fixtures. We have noticed extensive blackening of the chimney rocks located just above the fireplace opening, but this is the first time experiencing soot on the carpets. Has this really been an ongoing problem for folks with ventless fireplaces?

Kenneth Washio

Sweepy Hi Kenneth,
Sooting is actually one of the most common complaints we get from vent-free fireplace owners. You can read several such complaints in the letters above (check out the photos accompanying letters
#67 and #70).

You-Didn't-Ask-But Department: As you read about the headache, nausea, breathing problem and nosebleed issues in the letters above, you might want to reconsider the advisability of exposing your renters to the exhaust from your vent-free logs.


#128: Plaque or please

We have vent-less logs in our brick fireplace and an infrared vent-less stove in another part of our home. Home built in 1954, brick, block and plaster walls with high ceilings. Mold on the inside of the outer walls is a problem anyway just from no insulation. I run dehumidifiers to help. We are looking at closing off our fireplace and putting in a propane heater on the hearth. I have read that the plaque type heaters heat the moisture in the room and infrared heats the objects and that plaque type are a better buy for an older home. Will I still have the same problems from an unvented heater as I do with the logs (smelling, burning eyes etc)? We are looking at the newer models that are propane and natural gas all in one, what is your advice on these heaters. Your expertise would be greatly appreciated. Thank you.

Robbie Steele
La Fayette, Ga.

Sweepy Hi Robbie,
You asked for our advice, so here you go: don't try to heat your house with vent-free gas products, no matter which type. Aside from the immediate problems you're experiencing now (like bad odors and burning eyes), you will eventually face the effects of long-term exposure to gas exhaust.


#129: Vent-Free Gas Logs Gone:  Dizzyness, Drowsiness, Confusion Gone Too.

My husband and I moved from Florida to Tennessee and had an Empire VENT-FREE gas log set installed in our new home on 3/19/2010. That December, we began putting the fireplace to occasional use.  The smell from the logs was terrible, but the installers had told us repeatedly to expect an odor, so we dismissed this.

We used this log set, limited to only a few hours at a time, for 28 days  Within a week, with little use of the logs, all our beautiful house plants were dead.  Shortly thereafter, I noticed my husband was having trouble speaking his words correctly.  I, who am never sick, had  gotten to the point I could hardly stay awake for more than six hours at a time, except when we left the house.  On rising from bed I would be so dizzy, I could not stand without leaning onto the wall.  I kept thinking something is very wrong, but by then could not reason well enough to stop using the gas logs.

I am so glad I found your web pages about vent-frees.  Even after being so sick, my husband did not fully accept the problem was the vent-free logs till I showed him your site. 

January 14 was last day of use, and we both immediately started to feel some better. When we contacted the person who sold us the log set and told him we were being made sick by the vent-free gas logs, he danced all around the matter, saying he had never heard of this problem, and he has sold these for 25 years.  BUT he sent someone to our home to remove the logs, and refunded part of our money, enough said.  There is no doubt in my mind that if we had not stopped using that log set, we would have both been killed.

Thank you for your time and effort to make this info available to us.



#130: Extreme medical problems attributed to Vent-Free exhaust exposure.

My name is Ronald Bouthillier. In 2007 my wife and I  had a home built for us in Florida. We told the builder we wanted a gas fireplace in the family room, as shown in the model home we looked at. I explained that the fireplace had to be vented because I had COPD. At that time we lived in another state, but would travel to Florida occasionally to see how things were progressing.  During one visit we noticed that the fireplace the contractor installed was not vented. We pointed that out to the builder and were told that because we had cathedral ceilings and large windows and sliding glass doors it should not be a problem.

In January 2007 we were ready to move in: all that remained to be done was for the gas company to hook up the gas to the fireplace. The gas tech made a comment that there was little difference in the flame when turned on high or low, but did not seem concerned and said everything was working fine.

After living in the house a little over a year my wife and I both felt very tired all the time, and kept getting headaches while watching TV in the same room with the fireplace.  Eventually, I began to lose my voice and started coughing up blood. Went to see and ENT/Surgeon and he diagnosed me with throat cancer. After 35 rounds of radiation, it looked like I was cancer free. This was in 2008

During the next couple of years we used the fireplace very occasionally, and for only a few hours at a time because the odor from it was overwhelming and we kept getting headaches. Meanwhile I had been going to my ENT and radiologist regularly to be sure the cancer had not come back. As recently as December, 2009 my tests and examinations showed everything was fine.

The winter of 2010 was exceptionally cold, and we used the fireplace more regularly. Due to my COPD I sleep with an oxygen concentrator, and we noticed that the carpeting in the vicinity of its air intake had turned dark gray. I called the company who supplied my equipment and they took it away to check it out, leaving a replacement concentrator and new mask.  The smokey smell in my mask persisted, and when my wife cleaned the machine, the water was black. Only then did I begin to suspect that the problem was airborne soot from the fireplace, which I had been breathing in directly from the concentrator while I slept.

During this time my wife complained that the ceilings and walls were looking dingy. On closer examination we both noticed that the ceiling was showing shadows of studs and nails and corners were very gray, especially in the fireplace room. She called a painter to get an estimate to have the walls repainted and he asked if we had a fire in the house because it looked like there was soot on the ceilings and walls. He noticed our fireplace and asked if we were having a problem with it because he had run into sooting issues before. He chemically cleaned an area of the ceiling and we could see the stark difference between the cleaned section and the rest. He suggested we contact our insurance company as all the walls and ceilings in the house would have to be chemically sponged to get the soot off and then repainted.

Meanwhile I had been coughing up blood again and had to be taken to the ER because I could not breath and I had a rapid heartbeat. At the ER they found I had an irregular heartbeat, raging at 160 beats per minute. I spent about a week in ICU while the doctors tried to stabilize my heart with medication and, eventually, surgery. I had never had a heart problem like this and it does not run in my family. When I finally got out of the hospital I had an appointment with Dr. Brown, my ENT/Surgeon. Upon examining me he found that the throat cancer was "back with a vengeance", and immediately put me in the hospital and performed a laryngectomy (removal of my voice box) and a tracheotomy so I could breath. I remained in the hospital for 3 months. I will have to breath through the trach for the rest of my life, and must to use an electrical device to speak.

This all happened over the course of 3 years' exposure to the exhaust from the unvented fireplace.

The insurance company came to inspect our home, and after all was said and done agreed that the whole house had to be redone. The walls and ceilings had to be cleaned and repainted, all the rugs, curtains, windows and blinds had to be replaced because the soot had stained them. The forced air ventilation system had to be cleaned because the ducting was coated with the soot it had been carrying throughout the whole house. The total bill? $32,000 and never being able to speak normally again.

So if anyone says that non-vented fireplaces are safe let them read this and know what the consequences are. I will never have a normal life. I need to use oxygen all the time. I can’t walk across the street without getting out of breath. If anyone who reads this has any information or knows of any research being done on health effects of unvented gas fireplaces please let me know.

By the way, the insurance company gladly paid to have a new VENTED fireplace installed.

Ronald Bouthillier
[email protected]


#131: Moisture, Mold & Misery

I recently purchased a vent free infrared natural gas heater. After only two weeks of fairly steady use we had to stop using it due to high moisture levels in or house. We now have black mold growing in one of our bedrooms. We had to run a portable dehumidifier for three days to get moisture levels under control. The heater now sits unused. I would not recommend buying vent free products.

Keith Merrill


#132: Low CO Detector Readings, yet Headaches, Confusion Continue.

I bought a home about 15 months ago with a ventless propane fireplace. We used it last winter to help heat our home. I began having signs of CO poisoning such as irritability, confusion and severe headaches. I purchased a plug in CO detector alarm and have heard nothing from it. Last winter I eventually gave up on the propane fireplace, still believing it was causing the problems. My wife and I decided to give it another try this last fall. This time I bought a CO meter that reads down to zero ppm and up to who knows. I cranked on the ventless propane fireplace and have gotten nothing much as far as readings go on the meter.... sometimes one or two ppm. I took the meter to my shop where I burn wood and held it over some smoke coming out of the door..... and it zoomed way up quickly.... so I presume the meter is calibrated fairly accurately and is working properly. Since we were believing the tests, we decided to use the ventless furnace again, this second winter. I am getting bad headaches, feel confused, and am unreasonably irritable. I think it must be the furnace, but am baffled about my low or nonexistent readings on my CO meter. My wife, is skeptical about the furnace being the source. Am I just getting crankier in my old age. I just don't feel right or feel like myself... my mental status is degraded during prolonged us of this furnace. Help me understand what is going on.

Logan Swanson, Jasper, Arkansas

Sweepy Hi Logan,
Your confusion stems from the fact that you're chasing the wrong bad guy. Although vent-free fireplaces produce some CO (carbon monoxide), the big criminal is CO
2 (carbon dioxide), which your CO detector can't detect. To sniff out the real cause of your symptoms, invest in a CO2 detector, or an indoor air quality meter with the ability to sense CO2. Google CO2meter to view some options.


#133: Logan Responds

As you suggested, I purchased a home air quality sensor found on Google.  After setting it up outdoors where the CO2 was reading about 260 PPM, I brought it inside where it very quickly went into an alarm and then an error mode when the PPM display rose above it's 10,000 PPM maximum.  I have no idea how high the CO2 was, but it was up there.  Thanks for steering me onto the right path.  The propane fireplace is off (even the pilot light) now.  I will look into replacing it with a vented one.



Page 1 (Letters 1-25)     Page 2 (Letters 26 - 50)    Page 3 (Letters 51 - 75)    Page 4 (Letters 76 - 100)    Page 5 (Letters 101+)


Read about how much CO2 a vent-free fireplace exhausts into the breathing space

Read about a recent study of the effects of long-term exposure to CO gases

Read about respiratory irritation from vent-free exhaust in the breathing space

Read a posting about vent-free gas appliances from an indoor air quality scientist

Read what Consumer Reports Magazine has to say about vent-free products

Read letters in defense of vent-free products

Read our opinion about vent-free gas appliances

Read about a 2016 ASHRAE standard that could eliminate the entire vent-free product category in the US

Have a vent-free experience you'd like to report?  Here's a link to the Consumer Product Safety Commission website.


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