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What are Ventless Gas Fireplaces?

A ventless gas fireplace.
Some ventless gas fireplaces run on propane.
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  • Last Modified Date: 05 July 2014
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Ventless gas fireplaces are controversial but potentially beneficial sources of heat for a single room. Since they do not require a flue, chimney, or external venting ducts, they are much less expensive to install compared to traditional gas or wood fireplaces. Ventless fireplaces or heaters uses natural gas or propane as fuel and burns the gas with air from the room.

Some people install this type of fireplace to add an alternate source of heat to their homes, such as in a bedroom that gets especially chilly. Of course, the fireplace can also bring a cozy, decorative element to a corner, as they are available in many colors and styles. All that a homeowner needs is a line to deliver propane from a tank or a natural gas pipeline into the home, so they are gaining in popularity.

To choose from among the different types of ventless gas fireplaces, a homeowner should consider how he will primarily use it. Each has a rating for how much energy they consume and how much heat, measured in BTUs, they provide. Consumers should pay closest attention to the BTUs, because this figure will determine how large the room can be for the fireplace to function properly. A high-output fireplace should not be installed in a small room for the purpose of generating more heat.

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All kinds of combustion, whether gas or wood, requires the oxygen in air to create flames. Therefore, no fire could ever be truly "ventless," or it would extinguish itself. Ventless gas fireplaces are really using ductless or chimney-less technology, so they vent out into the room. That's why the volume of air in a room is very important. These fireplaces may take the place of central heating if the electricity in a home ever goes out, but most manufacturers recommend only using such a fireplace as a secondary source of heat.

Several states within the United States, as well as other countries, have completely outlawed such fireplaces because of health concerns. Canada, Massachusetts, and California don't allow people to install them because they could cause a build up carbon monoxide in a room, deplete the oxygen, and cause unconsciousness or even suffocate individuals in the room. Homeowners should check their local building codes before purchasing one of these appliances and make sure that they know how to use the device safely.

This type of fireplace also has other, milder health hazards. It can cause an increase in the room's humidity, for example, since burning gas or propane creates water vapor that can build up in a room. This may lead to mold and mildew growth, and although most forms of mold aren't truly dangerous, they will certainly increase allergies and could spoil fabric, photographs, and books.

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Discuss this Article

anon952490
Post 68

I have a gas wall heater in my florida room and have soot all over the wall ceiling and windows. What can I do to prevent this?

anon940448
Post 67

For all of the people who say they would never have a vent free appliance in their house, guess what? If you have a gas range in your kitchen, you already have a ventless appliance. There is no chimney for a gas range. Oeople try to argue with me by saying, "Well, I have an exhaust fan over my range." Honestly, do you turn on the exhaust fan every time you make a cup of tea or even every time you cook? The answer is no, you don't. Gas ranges have been in kitchens for decades, even in California and Canada, so I guess Canada and the states that have outlawed ventless fireplaces had better run into everyone's homes that have gas in the kitchen and tell them to tear out their gas ranges also.

Even the most advanced carbon monoxide detectors on the market, which I have in my house by the way, always read zero and my ventfree gas fireplace runs 24/7. The people who are complaining about soot and odors are the same people who do not change the filters on their primary heating system until they have a problem with that as well. Anything mechanical needs maintenance, of course. Let's all just blame the product when it fails or doesn't function properly.

Common sense, which I am not seeing much of in these posts, tells you problems will arise if you ignore the manufacturers recommendations. The people on this site who explain how they properly maintain their units and how great these units are, have brains and do not seem to be complaining because they will not pay a professional to properly service these wonderful, affordable, and yes, dependable heat sources.

I have been selling and servicing ventfree fireplaces for over 15 years now, and I even have a customer that has had lifelong problems with asthma and recently had part of a lung removed due to cancer. She uses her ventfree fireplace that I sold her 24/7 also. It kept her in her house after Hurricane Sandy for 11 days while she had no other source of heat. So, try to negate anything I have said! Good luck with that!

anon935366
Post 66

Why does the pilot make a bubbling sound?

anon321983
Post 65

My wife has been diagnosed with COPD, (Chronic Obstructive Pulmonary Disease). This was caused by smoking for years, but that's beside the point.

We bought a home that has two 'ventless' propane heaters built by Rinnai. It wasn't until she was diagnosed that we were able to put everything together to figure out that the unvented heaters were causing her to have terrible health issues, including lung infections, one after another.

I decided to purchase three 1500-watt electric heaters (and since the kids have left the roost) restricted all living to the upper floor of the house (which is great, as the first floor is an upgraded basement, all cement, and has a tendency to get moldy, perhaps due to all the cement blocks/floors).

Since switching to electric heaters plus adding 'sonic humidifiers' (and one negative ion generator), she no longer has any complications with her breathing. I am sure the unvented propane Rinnai is the culprit, (even with 'nearly zero' carbon monoxide output, according to my meters), because turning it on without her knowledge results in almost "instant distress."

Therefore, I do not recommend 'ventless' heaters to anyone. Common sense tells you they will deplete oxygen within your home (which is why you should always crack a window when one is running), and despite the “experts" saying they are safe, why would they tear up someone with a lung disorder if they truly are safe? That's my twopence worth. Thanks for reading and be safe! (Turn down your heaters to 50 and visit neighbors daily)!

anon313846
Post 64

To answer some of these "sooting/blackening" questions and remarks:

If your vent-free/ventless gas system is producing soot (which is actually carbon build-up as opposed to soot), what is happening is that the flames are being "impinged." The most common caused is the improper setup of the media kit on the burner. Check your user manual to make sure the logs/rocks/etc. kit is installed properly and the flames are rising up through the appropriate gaps. There are other reasons this can happen, but this is very common.

anon311355
Post 63

Can someone please explain how thermostats work on gas log sets? Say the thermostat is set to 68 degrees and the logs go off when the room reaches 68. What exactly 'goes off'? I'm wondering what controls the gas flow (as opposed to the flame).

anon294489
Post 62

I have a ventless fireplace with an electric rocker switch on wall beside it to open gas valve. If you lose electric power, this switch would not work to open the gas supply valve - right? What work around would have to be done in case where there is no power to supply gas to the fireplace for heat?

anon285259
Post 61

We want to install a ventless fireplace in a screened porch. Does anyone have experience with this idea and if so what are the downsides? With plenty of open air, I'm assuming that many of the problems discussed here would no longer be a problem.

anon268267
Post 60

I get nosebleeds when the air is too dry in the winter, so (within limits) humidity is a good thing. I would think carefully about ventless heaters as a primary source of heat (although my gas installer speaks highly of them).

However, as an alternative form of heating they're wonderful, both *because* they produce humidity and as a cost-effective backup to a primary heating source.

anon235178
Post 58

Those of you who are having problems with soot or odor need to read the manual. Ventless gas logs are extremely efficient and safe if used properly. Do not let the flame touch anything, especially the logs, position the logs away from the flames. Purchase a unit with a thermostat so it will not over heat and do not use a high BTU unit in a small room with the doors closed.

A little bit of common sense will go a long way, save a lot on the heating bill and keep your home comfortable and warm.

anon230340
Post 57

Ventless gas fireplaces are nice but we are on our second one because they tend to start to have trouble lighting the pilot light. Our biggest problem is trying to find someone to repair them! Beware. If you buy one, then you will have a had time trying to find someone to repair them. Everyone tells us they don't repair them because they are unsafe.

anon229217
Post 56

I am reading all these comments as I have had a flueless gas stove for several months now. It was installed by a registered gas fitter who actually sold me the fire from his own house. Have only started to use it since the weather turned colder. We leave the pilot on constantly and it keeps the room nicely aired. Had to have a vent installed through the wall

(regulations in UK).

Since using it more am getting a dry throat and irritating cough and have noticed that I look and feel flushed a lot of the time. I have the CO monitor next to the fire and it registers nothing. Any suggestions please? Also, my gas boiler has started to act up and is cutting out constantly. Could there be a connection? I will have to have it fixed but money is a bit tight right now. Any advice is much appreciated.

anon180719
Post 55

In my opinion, ventless fireplace is the best way for people who don't have chimney in their houses. Ethanol burning fireplace is ecological and environment friendly.

anon150484
Post 54

I just installed my vent free stove and LOVE it. The manual stated the smell would go away after the new logs were "broken in" after about three hours of burning, and it did. We experience the smell for 5-10 minutes after we start it, then it is gone.

We turn the furnace fan to ON causing the hot air from the stove to be sucked into the cold air return and circulate it through-out the house. Our heating contractor said the fan running constantly wouldn't cause an increase in electricity because the electricity used to keep it at a constant speed equals the electricity needed to stop and start numerous times a day.

With my stove set at the lowest level and my furnace thermostat set at 65 degrees (50 ft away from the stove and around two corners) my indoor temperature was 69 degrees! Over 2000 square feet! Because of the furnace fan circulating the warm air, we don't have any "cold spots". The warm air gets into the rooms that are closed. We don't notice an odor. If anyone is having problems with their vent free stove, have it serviced or get a new one. Our experience has been great.

anon149467
Post 53

I have a new ventless fire place and it is quite noisy. When burning it sounds like large waterline running inside a wall. Any remedies?

anon148659
Post 52

Help me, please! I have the same problem as everyone has posted, turn on ventless gas fireplace and the house fills up with gas. It's horrible. Now I hear from the hubby is we should have put in a real fireplace. Can someone please tell us the problem? I've had the fireplace people out they say there is nothing wrong with the system but everyone smells it.

anon147579
Post 51

just installed a new ventless natural gas log set when ever it turns on the odor is horrible it is 30,000BTU,I seem to be the only one to smell it or have any ill effects from it like headache breathing issues & sick to my stomach any suggestions? Thanks

anon146633
Post 50

We just got two ProCom ventless gas fireplaces from Northern Tool. 23,000 btu. They were the best price/value on the market. Even the surround is furniture grade wood.

Anyway, I turned off my central forced air gas heat. We've been heating our 1,200 sf first floor exclusively with one fireplace since about Jan 5th. Outstanding. No headaches. No respiratory issues. Looks beautiful. We are wondering what our gas bill is going to look like.

The only drawbacks so far are that the units we purchased don't run on a thermostat and we have to spend on electricity to run ceiling fans to distribute the heat around the house. But all taken, I wish we'd done this years ago. I'm very sorry for those who are not having the great experience we're having. I hope you can solve those issues and get a million times the pleasure we're getting. Best of luck, don't give up.

anon143891
Post 49

We moved in our new house back in november. We have two ventless fireplaces that we only use as secondary heat.

Up until this past weekend, we had experienced no problems other than my eyes feeling dry after running it more than 15 minutes. The other day we experienced a very slight odor and both of us starting having discomfort in our throats and chest like something was burning.

None of our three CO2 sensors registered anything. I cut the logs off, but the discomfort continued. We both feel a little sick even away from the house. I don't understand what's going on.

anon143082
Post 48

oil based finishes and polishes will cause soot and odor.

anon136052
Post 47

I have a ventless gas log insert that uses propane and it does a wonderful job as a supplemental heater. However, something to consider is, in any home where a flame producing heating product is used, be it the oil burner, gas stove, gas fireplace or otherwise, vented or not invest in a "good quality, UL listed CO/Carbon monoxide detector". If you experience headache, burning eyes, or other issues, stop using the unit immediately and have it checked by a professional.

Make sure you have the unit installed to the manufacturer's instructions. Clean and maintain the unit as if your life depended on it, because it may not just be your life, but that of your family too.

anon135635
Post 46

i have had a ventless fireplace for eight years and we had a new floor installed and then had to disconnect the fire place. we hooked the gas line back up now after a week if using it i have soot on the wall and in front of the fireplace. could someone please tell me what's wrong with it?

anon131680
Post 45

To post 44. That is very very bad. A headache could possibly mean you are suffering from carbon monoxide poisoning. I would get it checked out as soon as possible.

anon129803
Post 44

I have a new home with ventless fireplace, turns on and off with a thermostat. I wake up in the morning coughing and have a bad headache, so I'm starting to think the fireplace is the problem.

When I lived in CA we did the same with our fireplace but it was vented and never had any problems with coughing or headaches.

anon127310
Post 43

I have had two sets of vent free gas logs (in two different homes). I have had no problems, only slight light grey sooting when I didn't thoroughly clean the burner / logs before using them for the season.

I did the installs myself (I was a union plumber), read the directions and cautions (which are mostly common sense), paid attention to proper sizing, air exchange, etc. (and actually measured & calculated it). Result has been no odor, no sooting (other than when my fault), no condensation problems, etc.

Please pay attention to these details and use a knowledgeable installer, not just someone who opens a fireplace shop and hires kids to install them. Read the proper sizing and air requirements and ask the installer about them so that you understand (and don't take any BS or vague answers).

The key is proper size, location and installation through knowledge, not guesswork. Both of mine are natural gas, and I had to adjust the pressure to fall into required pressure. The second house was fine. Both sets work flawlessly. The older one is nine years now, and never had a problem with either. A little common sense goes a long way here.

anon127024
Post 42

Very interesting posts. I've had ventless gas logs for 8 years now and have had absolutely no issues with them.

What's up with all this soot? And as for moisture - a previous post said he turned off the humidifier on his furnace when he uses the ventless gas system. That's because in the winter you want humidity in the house, unless you like the static electricity that results in these very dry environments.

So I don't see a little humidity as a bad thing; I seldom burn mine more than six hours in any day and usually no more than two. As for odor, I don't remember when it was new but now I don't smell a thing.

I've got three other friends and none of them have any problems either and one of them lives in a huge house and heats exclusively with about 8 ventless gas heaters and has for about 10 years. Any others have this experience?

deuce
Post 41

is it OK to run a vent free lp gas fireplace without the logs in it?

anon124931
Post 39

My whole house is covered in soot. My husband and I called the company and had them take both of the logs out and cap off the gas. We are in the process of painting every room in the house because of the soot. I have lost two flat screen tv and a computer monitor due to the soot. I am at this point so mad. I will be filing a complaint with the BBB and consumer affairs and calling the manufacture of the logs.

anon124635
Post 38

We've just moved into a new house (12 days ago) and the off gassing of the entire house is horrendous. The ventless gas log: never again. I've lived in several new houses, but none with a ventless anything (and have never suffered so much with lung issues and headaches). People: Use your heads. If it sounds too good to be true, it is.

We're living in a chemical world loaded with carcinogens. We're all being sold a bill of goods that is damaging our health. If we can't get the air quality improved in our home soon, we're moving out.

anon102289
Post 37

I am an environmental hygienist who has seen several soot issues in homes with ventless fireplaces. It seems to be prevalent in homes where additional 'incomplete' combustion is occurring - namely from candles and/or plug-in air fresheners. Carbon monoxide is also an issue. Keep a window or door cracked open when using one of these devices.

anon79281
Post 36

I have a gas ventless fireplace. I recently took the gas out. Am I able to use gel fuel in the cans with my gas log set?

anon79126
Post 35

I have a ventless fireplace and realized I had soot all over the house, particularly ceiling and on windows. How can I avoid getting this or does it mean something is wrong with the fireplace?

anon77422
Post 34

Nice article about ventless gas fireplaces. But, ventless gel fireplaces actually accomplish the same at way more than half of the expense.

anon68681
Post 33

I have a ventless propane fireplace in my home that was built over a year ago.

I have been complaining that I smell a peculiar odor and cannot convince my husband nor the installer of the fireplace that there definitely is an odor.

I was not aware that others have experienced similar problems until my neighbor told me of this website. Please help!

anon68166
Post 32

Just moved into a home with a ventless propane fireplace that smells awful. Can ventless be converted to vented?

tomrains
Post 31

I have a similar problem like #1 anon4597. I was wondering the cure.

anon63427
Post 29

The terrible smell sometime experienced when using your vent free fireplace is from VOCs (volatile organic compounds) already in the air such as air fresheners. The plug in kind are the worst. Also candles off-gas even when not lit. The more fragrant they are, the more off-gassing. If bad smells or soot are a problem look for something in the home that is off-gassing VOCs.

anon63147
Post 28

My husband seems to think that he can safely heat his garage with an old natural gas fireplace unvented. It is a B vent. He is not convinced by me that it is dangerous.

Can someone please spell it out for me in plain English why he shouldn't do this?

anon58540
Post 27

I have a propane fireplace and have used it in previous years as backup. With the price of propane I have decided to convert to natural gas but they tell me it is not possible. Can a propane log be converted to natural gas?

anon58131
Post 26

I have a new set of Ventless logs. I can get the pilot light on, but they won't stay lit and burn, I talked to the guy who installed them two years ago, and he says they need to be cleaned with a shop vac? Any suggestions?

anon57711
Post 25

I moved into a house recently. How do you tell if a gas fireplace is ventless or vented? My house has a chimney with a flue but the fireplace's burner doesn't have any silica around it and it shuts off after 10-15 minutes which makes me think it has an O2 sensor on it.

I don't want to use it if it just vents out the chimney. I'd rather close the flue and use it for secondary heat if it's the ventless kind.

anon57113
Post 24

I have just installed a ventless gas fireplace in my home. I assumed the flames would have been silent or close to it. It sounds like a whoosh

of air when it's running. Is that just normal, or am I getting too much gas?

The gas line in my house is 1/2 inch and it is reduced to 1/4 before it gets to the fp. Are there any additional valves needed or is this a normal sound? I've seen plenty of vented gas fp's before but the flames are behind glass so I can't tell.

anon56077
Post 23

Do you have to have a large propane tank in your backyard for the ventless propane fireplace or can you use a propane tank like you would use for your gas grill, for occasional use? I know they make adapter valves for the smaller tanks but is there enough pressure in the small tanks?

ssandecki
Post 22

@anon4597: This is common with propane based ventless fireplaces; especially if they aren't close to 99.9 percent efficiency. I would consider getting a new unit that uses natural gas or gel fuel; you might be able to get a new burner set to correct the issues. Always make sure your ventless fireplace is near or above 95 percent efficiency.

anon50957
Post 21

I have a DECA ventless natural gas fireplace. It starts right up but goes out in about ten minutes. If you leave the logs out it will burn for ever. What's wrong?

anon49736
Post 20

I've sold and serviced vented and vent-free gas logs for nine years. Both have their place. In Alabama, we rarely have customers complain of odor. You should never smell gas. It's even rare to smell gas when lighting the pilot. When we do, some of the common causes we see are as follows: All new vent-free logs when first installed have to finish curing. Some manuals will say burn 4-10 hours. We tell customers, if possible, to open their damper, if they have one, or open windows or doors and burn on high for 2 to 2 1/2 hours. This is usually long enough to take care of that smell. Also, dust burnoff after they've sat all summer is common. Dusting as best you can usually helps but you still have some dust burnoff. If you experience sharp, stinging smells and headaches, we find that some people rearrange logs, which is a big no-no, or place lava rock or other items on the burner causing flame impingement. You should never see soot build-up on vent-free logs. I had one guy who had marshmallow dripping on the burner. Not a good idea. Another item with headaches could be something causing the pressure to be too high or too low. On propane units, the regulators on the tanks can cause this if they go bad. Other things we've seen that cause odors are candles on the mantel, painting/staining in the house, placing vent-free logs in a woodburning fireplace that wasn't cleaned. Old creosote that gets wet can make its way into the firebox and creates a horrible musty smell. I don't have all the answers but these are a few things i've noticed around this area. Hope it helps someone.

anon49155
Post 19

I have a ventless propane fireplace in big open room in my basement, but there is such a bad odor when we try to use it. I have had three different professional people come in to check, and they say everything looks good and there's no problem. Can these be converted to vented?

anon48484
Post 18

Anyone with a ventless fireplace should have it cleaned annually by a service professional or learn to do it themselves. Maintenance can prevent soot build up and odors. I have been servicing ventless fireplace units for over ten years, and have my opinion that they are efficient, but definitely do have downsides. I tell people to keep them immaculately clean and free of dust and spider webs to prevent harmful byproducts.

anon48002
Post 16

I have a 25,000 btu natural gas ventless fireplace heater in the basement. No soot or issues, but there is some odor if I don't clean it, so I clean the burner with a can of compressed air before fall start up and again in mid winter. I turned off the furnace humidifier because the fireplace adds water to the air. We use it for a couple of hours a day and if the power goes off. I crack two windows about half an inch on opposite sides of the house if the power goes off and the heater is used for more than a couple of hours. I have two CO monitors and neither has ever gone off. If you have a ventless fireplace that is sooting up your house something is really, really wrong. And I would never have one of these in my house without a CO monitor.

bcoleman
Post 15

I want to know the answer to the last post by anon4597. Our fireplace also has an odor. It smells like a bus drove through our living room. Does it just need to be serviced? Is it dangerous?

anon23705
Post 14

what can be done about window condensation caused by ventless gas fireplace?

smurdock
Post 13

My landlord installed a ventless propane heater woodstove style. I would like to know if it can be vented? I have a lung disease and refuse to use it.

anon21013
Post 12

There is a reason many states and Canada are outlawing these extremely dangerous fireplaces! If you read the instructions, it says to open a window before you light these "heaters". Not a great way to heat the house. They all should be banned. I work for a utility and have ran many tests for CO when these are running. Think about venting your furnace into your home. Please get a direct vent insert/ freestanding fireplace. They are a real heater, and no one will be poisoned, or possibly die.

tjthompson
Post 11

I have enjoyed ventless gas heaters for a number of years, but I now have a severe soot problem. It has affected almost every room in my house There is no question as to what is the problem, but I don't know how to fix it. I've cleaned the burner holes and the hole just before the nozzle, but I really didn't see a reason for the soot. I'm sure that someone has the right combination to cure this.

anon10108
Post 7

I’m only seeing info on propane ventless fire places but what about the ventless fire place that uses fire Gel and can be moved from room to room, home to home. They say their no maintenance no ash no mess “A portable gel fireplace is the safest ventless fireplace option available. Even when compared to a conventional wood burning or gas fireplace, a gel fireplace still comes out on top when it comes to safety. Wood burning fireplaces have hot embers popping out through the screen or floating up the chimney, and if your chimney becomes clogged a wood burning or gas fireplace can be extremely hazardous. Gas log fireplaces, whether vented or ventless, can accumulate deposits and clog the gas jets, causing it to fail to burn properly. Gas line fittings can come loose and leak harmful natural gas or propane into your home. All conventional fireplaces require annual service or repair in order to function safely. Gel fireplaces need no servicing. Their safety and longevity remains steadfast for as long as you own it. A gel fireplace is safer in your home than burning a candle!”

pkannon
Post 6

I am interested in buying a house that has vent-less gas logs in its great room. One of the other homeowners had their gas logs on and their mantle got very hot, so hot they could not touch it. What could have caused this?

anon7795
Post 5

Soot and smoke has been caused by my "ventless propane stove." My ceiling and walls are covered with a black film. Also the top of the stove is turning black.

anon7078
Post 4

Soot and smoke has been caused by my "ventless fire place." My kitchen cabinets inside and out and dishes are covered with a black film. Also the front of the fireplace is turning black.

anon6692
Post 3

Soot as well as bad air has been caused by my "ventless fire place." Whats up with that? We stopped using them and this house has 6 of them. They really are NOT safe!!

anon4802
Post 2

have enjoyed ventless gas logs in my fireplace for about fifteen years now.they keep my down living area of 1700 sq feet quite comfortable and yes they are great but mine are installed in a regular masonry wood burn fireplace and yes i always leave the damper slightly open and this vents the air just enough that i do not lose excessive heat up the chimney and this also prevents mold or condensate from collecting around my window sills, most definitely would have window sill mold and condensation issues without keeping that damper vent open one notch. when used in this manner i give them two thumbs up but from my personal experience operating in this manner is the only way i would consider their use regarding personal health and safety.

anon4597
Post 1

I have a ventless propane fireplace in my living area, roughly 30ft by 36ft with 18 ft vaulted ceilings. The problem I have when I use my fireplace is that is has an odor that is similar to the old oil burning furnaces, very rank. Do you know of a cause of this or a fix for it?

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