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Vented - vs - Vent Free Gas Logs
Find out which is best for your home...vented or ventless!

Similar Pages: Gas Log FAQs page | Why Do Ventless Gas Logs Smell

Basic Overview

Vented Gas Logs Require a Fully Functional Wood Burning Fireplace and must be burned with the damper open, Ventless (or Vent Free) Gas Logs can be installed in either a wood burning fireplace, or a ventless fireplace that is rated for aftermarket ventless logs and are burned with the damper closed. Ventless gas logs will produce more heat, while vented gas logs will look much more realistic. Read the Pros and Cons of each below:

Vented Gas Logs:

"Fully Vented" gas logs must be burned in a fireplace that is capable of burning real wood and must be burned with the damper open. The reason for this is that they do not burn the gas cleanly and create exhaust that is very similar to burning a real wood fire. This exhaust needs to be able to go up the chimney. The real beauty of vented gas logs is that they produce substantially more yellow flame than ventless logs which makes them look far more realistic. The downside is that most of the heat goes right up the chimney.

However, In most cases, you can offset this heat loss by slightly closing the damper...but you must be careful that the exhaust from your logs is not coming into the room because, just like burning real wood, it contains Carbon Monoxide. A good way to test this is to turn on your gas logs with the damper slightly closed. Hold a lighter or candle in front of the fireplace opening near the top. If the flame from the lighter (candle) is being drawn in toward the fireplace, then you are OK. If the flame is standing still or pushed out toward the room, then your fireplace is not drafting enough and you must open the damper more.

Positive Features of Vented Gas Logs:

  1. Extremely realistic flame pattern that looks like a wood fire.
  2. Flame is much taller than ventless logs
  3. Flame dances and wraps around logs like real wood.
  4. Does not require a CO detector
  5. Since the damper is open, most of the smell will go up the chimney

Negative Features of Vented Gas Logs:

Do's and Dont's for Vented Gas Logs
(Additional information you should read before buying Ventless Gas Logs)

  1. Less heat than ventless logs (probably won't heat your room)
  2. Uses slightly more gas than ventless logs

Check out some Vented Gas Log Installation Manuals Here before you purchase.

Ventless Gas Logs:

Ventless gas logs (often referred to as "Vent Free" gas logs) have specially designed burners that burn the gas cleanly and produce almost no exhaust...somewhat like the way a gas range in a kitchen works. Since there is little or no exhaust, they can be burned with the damper closed.

The beauty of this type of system is that 99.9% of the heat produced by the gas logs goes into the room, so they produce substantially more heat than their vented counter-parts. However, there are many negative features commonly associated with ventless logs that you must be aware of before you decide to purchase them:

Positive Features of Ventless Gas Logs:

  1. Much better heat output than vented gas logs
  2. Less pollution
  3. Slightly less gas consumption

Negative Features of Ventless Gas Logs:

Do's and Dont's for Ventless Gas Logs
(Additional information you should read before buying Ventless Gas Logs)

  1. The main byproducts of burning gas cleanly are Carbon Dioxide and Water Vapor. Because of this, ventless gas logs will introduce excess moisture into your home which can result in mold or mildew.
  2. You must be careful not to burn your ventless logs for extended periods of time with windows closed, otherwise they can potentially deplete the oxygen in your home.
  3. If you burn your ventless logs for more than an hour or so, you must crack open a window to allow air into your home to replace the oxygen burned by the ventless logs. This will introduce cold air into the room and offset some of the heating benefits that ventless logs claim to have.
  4. Ventless logs produce an odor that many people equate to the smell of burning kerosene. If you have a sensitive nose, you may not be able to handle the smell and will be greatly dissatisfied with ventless logs. On the other hand, we've heard some people who like the smell because it reminds them of their childhood days at Grandma's house. (Read Why Ventless Gas Logs Smell)
  5. Ventless logs can cause eye irritation and coughing spells to those who are sensitive.
  6. Ventless logs are not legal in California as well as some cities and municipalities. However, you can still purchase ventless logs from us if you live in will just have to burn them with the damper open (which really defeats the purpose).
  7. Ventless logs are required to have an ODS (oxygen depletion system) as well as a CO detector...which might tell you that there are some risks involved in operating them if these systems fail.
  8. The flame pattern with ventless logs is not nearly as realistic in comparison to vented logs. Because the gas must burn cleanly, the flame height is very low, it is more blue than yellow and appears to be more nervous and less lofty.
  9. Also, you will find that the flame does not dance around like a real wood fire and very little of the flame actually touches the logs. The reason for this is that when the flame touches the logs, it gets cooled off and does not burn cleanly and starts to produce soot and exhaust gases.
  10. Installing vent-free gas logs is not a DIY job. Installation must be performed by a professional who can do the proper tests on your gas pressure and make sure that the installation meets building codes and follows the specifications required.
  11. Clearances to combustibles is different than that of wood burning fires or vented gas logs. If there is a mantel above the fireplace, you may need to install a hood to divert heat away from it. You should check the Installation Manual for the Ventless Logs for clearance requirements before you order them.
  12. There are also BTU limitations based on the cubic feet of air available to your room. The maximum BTUs allowed is calculated using this formula: Room Width x Room Length x Ceiling Height x 20.
  13. Ventless gas logs may not be legal in a bedroom or confined space (differs with local building codes).
  14. Other restrictions apply with each of the various burner systems available, so again, you should read the installation manual pertaining to the ventless logs you are considering "Before You Purchase".

Bottom Line: We highly recommend that you purchase vented gas logs. You will be much happier with flame that they produce and less likely to experience discomfort from odors or irritation. We only recommend ventless logs when maximizing the heat output outweighs all of the other negative aspects.

Gas Logs Questions and Answers

We will respond to email inquiries within 24 to 48 hours. Our Experts can provide quicker and better service over the phone if you choose to include your phone number (not required)

Contact Information

Question: I do not really need the heat, and I have a fireplace already,but, the damper is either all the way open or completely closed. can I get that fixed so i can have it open part of the way so all the hot air does not go up the chimney thereby kind of making it silly to have one
Answer: Technically, a vented gas log is supposed to be burned with the damper completely open. Plus, you cannot ever completely close the damper just in case there is a gas leak, so there is a clamp that is included with the burner system that gets attached to the damper to prevent it from ever closing completely. So if you do not really need the heat, then the way your damper operates is sufficient for a vented gas log. Whether you close the damper slightly to preserve some of the heat will not make much difference, you will get most of the heat from a vented gas log radiated into the room from the ceramic in the logs themselves. If you are really concerned about getting heat (which you say you are not), then you should consider buying a ventless gas log.
Question: My daughter has vented gas logs in her bedroom which is about 24x36. It is her primary heat system. Recently we noticed that the ceiling and top part of her walls were becoming covered in black soot. Why would the logs start this and is it dangerous to them. They have a 1 month old that sleeps in that room as well. I have noticed that some of the baby toys that are plastic have the black on them also. I am very nervous about this. Would it be better for them to get ventless with a heatalator?
Answer: Please stop using the gas logs immediately, it is dangerous to use them if they are producing soot. Where there is soot, there is also carbon monoxide, which as you know is a lethal odorless gas. You need to have your gas logs serviced or replaced because they are no longer burning cleanly as vent free gas logs should. Some Heating and AC companies are qualified to service ventless appliances, so use your local yellow pages to call around. Or, you can use the resource on this page to locate a professional who is qualified to service your gas logs: Locate a Gas Log Service Professional.
Question: We are thinking about converting our wood burning fireplace to gas. We obtained 2 estimates from local companies. One company told us that in order to go ventless, we would have to change out entire fireplace, box, chimney insert, basically replace everything. The other company said it would be no problem to convert over and was much more reasonable. We want to make sure it is safe and no fire hazard, not sure which one to believe.
Answer: If you can email me some pictures of your fireplace I may be able to help clarify whether or not you can use ventless gas logs in it. If it is a prefabricated fireplace, the answer will be determined by the owners manual for the fireplace. In order to find the owners manual, we will need to know the brand and model number of the fireplace. To do so, look for a metal label somewhere around the fireplace opening. If you find it, send a picture of that as well. If it is a masonry fireplace, you should have no problem using ventless logs. In either case, email me some pictures and I will help you determine what you have. Email your fireplace pictures to:
Question: I have a set of gas logs in my house. They are after market logs. We want to make sure they are safe to use. House do I tell the difference between vented & ventless.
Answer: If you can email me some pictures of your fireplace and gas logs, I may be able to identify them. Email your fireplace pictures to:
Question: I live in the Nashville area. Do you have any contacts here who can quote me to install a wood burning fireplace? I have no flue, have ventless. I hate it- I smell gas and no oxygen. My kids and I are too sensitive to it, but we LOVE fireplace ambiance. Thanks!
Answer: I cannot give you a contact to install a fireplace in your local area. I suggest you check the yellow pages to find a local fireplace shop. They are going to be the best resource for getting a new fireplace installed. You may also do well by referring to the resources available online at the National Fireplace Institute.
Question: We have a ventless gas fireplace. It is located on an exterior wall of our brick home. The wall on the exterior is on our patio. What would be involved to convert it to vented? What do you think would be the approximate cost? Who should we call if it is a reasonable thing to do? Thanks very much.
Answer: For starters, you cannot "convert" a ventless fireplace to a vented fireplace per-say. You must remove the existing ventless firebox and replace it with completely different type of fireplace that has a chimney or vent. My suggestion is to replace it with a wood burning fireplace. This allows you to burn either wood or gas logs. It is also best for resale value since it allows the potential buyer the same options.

As far as the is all over the place depending on what you decide to do. You should have a local professional to come to your home and give you an estimate. When I sold fireplaces at a retail fireplace shop, the final cost including installation ranged anywhere from $7,500 to $25,000 depending on the complexity of the installation and the finished appearance of the fireplace. We also sold simple to very elaborate hand carved fireplace mantels that could cost as much as $10,000 just for the mantel. So how the fireplace is finished has a huge impact on the cost. The bare minimum would just be a fireplace with no decorative surround...maybe just a brick or tile facing with some wood trim...for a total of about $7500 installed (that is a prefabricated wood burning fireplace with a metal chimney).

I would suggest visiting local fireplace shops. They should at least be able to get you started in the right direction. These are the options you will need to explore. I would suggest you do some research online about the differences between these:

B-Vent (natural vent) gas fireplaces
Direct Vent gas fireplaces
Zero Clearance wood buring fireplaces.

We do not sell fireplaces (although I did for many years in a local fireplace shop). We sell only the gas logs that go into an existing fireplace. So if you like the looks of the vented gas logs you see on our website, they would require you to have installed a wood burning fireplace with a gas line piped into it. Vented gas logs are much more for enjoyment and realism than for heat.

Here is a link to our vented gas logs:

You may also want to use the resources at the National Fireplace Institute website. You can find qualified fireplace installers in your area using their resource locator. Here is a link to their website:
Question: do vented logs without doors remove oxygen from the air....?
Answer: Fire always consumes oxygen. The question is whether or not the oxygen gets replaced or depleted from the home when burning a gas log. When it comes to the depletion of oxygen in a home (or room), the difference between vented and ventless logs is this:

Vented gas logs are burned with the damper open, so just like a real wood fire, a draft is created that draws the exhaust up the chimney and outside your house. This draft creates a vaccuum which sucks air into your home to replace the air that is drawn up the flue. So with vented gas logs, the oxygen that is consumed is replaced by fresh air from outside...thus eliminating the worry about oxygen depletion. The benefit of this sort of combustion is that it does not matter whether or not the gas burns cleanly. This allows gas log manufacturers to starve the fire a bit, which means the oxygen to fuel ratio is not ideal and the gas does not burn completely. The result of this type of combustion is a very lofty natural looking yellow flame that looks much like a real wood fire that produces exhaust like carbon monoxide, carbon dioxide, carbon (soot) and water vapor. Hence the reason the damper must remain open.

Ventless gas logs are designed to be burned with the damper closed, so they must be designed to burn the gas completely (cleanly) so that carbon monoxide does not enter the room. When the proper air to fuel mix is used to burn gas completely, it produces a more vigorous blue flame that is not as realistic as the yellow lofty flame that vented gas logs produce. The benefit of ventless logs is not the appearance, but the fact that all of the heat produced goes back into the room instead of up the chimney. Because the chimney is closed, no draft is created, which means that air from outside the home is not pulled in to replace the oxygen that is spent during combustion. Also, the water vapor that results from burning gas is not vented outside the house either, so a lot of moisture is introduced into the home as well.

FYI: both vented and ventless gas logs cannot be burned with glass doors closed with the exception of one model designed by R. H. Peterson...or with a gas fireplace or gas fireplace insert that has special venting designed for that purpose.

For more information about the difference between vented and vent-free gas logs, read this: Vented Gas Logs - VS - Ventless Gas Logs.
Question: Can ventless logs be installed where vented logs are currently installed for more heat ?
Answer: Ventless logs have limitations on the type of fireplaces they can be installed in. If it is a masonry fireplace, the answer is most likely yes. If it is a prefabricated fireplace, you must refer to the owners manual or consult with the fireplace manufacturer to determine of ventless logs are approved for the model of fireplace you own.

There are also limitations based on building codes in your city. For example, ventless logs are not allowed in the entire state of California and in portions of Texas.

Can you email me some pictures of your fireplace? If so, I may be able to give you more direct answers. Also, let me know the city and state in which you live. Email to:
Question: Can I leave my vented gas log burning for long periods of time - 24 hours plus? Is there any thing that would cause a gas fireplace to "over heat"? We had an extended power outage and I wondered about burning the fireplace for that long of time.
Answer: There may be no issue with leaving your gas logs on for extended periods of time if you have a wood burning fireplace with a Peterson gas log in it. But I cannot say for sure without knowing the type of fireplace and gas log you actually have. Can you email me some pictures of your fireplace? If so, email them to: and I will try to give you more direct advice.
Question: I am trying to determine if the Glow Fire gas logs model 2 A is vented or non-vented. They are 24000 Btu and appoximately ten years old. Please respond to as sone as you can. Thanks.
Answer: Please email me some pictures of the logs and burner system so I can make the determination. Email pictures to:
Question: How much expense is involved in venting a fire place that now has vent-free logs. Can it be done with out replacing the existing logs. Our home has a vent-free fireplace in the living room, and a large vent-free fire place in the family room. The large fireplace also has a blower in it. Thanks SB
Answer: Unfortunately, there is no way to convert a ventless fireplace into a vented fireplace. Ventless fireplaces are not designed to have a vent added to them. Your only alternative is to tear out the existing ventless fireplace and replace it with a vented fireplace. You cannot use a vented gas log in a vent-free firepalce, nor can you burn wood in it. The cost to replace your fireplace with a vented fireplace will vary widedly depending on the location in your home. It can be anywhere from $5,000 to $20,000+.
Question: can you have an electronic ignition for a pilot light on vent free logs?
Answer: Yes, many of the Ventfree gas logs on our site are available with Electronic Ignition. To choose this option, simply view the product detail page of any of the Vent-Free log sets to see if the option shows on the page in the control options dropdown menu. You can also use this link on our search page to find all Ventless Gas Logs with Electronic Ignition.
Question: in nov 1995, i purchased a perterson 30 LP gas logs (g oak) with a wall switch. they were put in the fireplace in the great room--27X42- kitchen,eating area and den. the smoke was so bad tht they even smoked up the dishes and glasses in the kitchen. you could even see the smoke in the room. it was a big mess!!! I finally threw them in the woods. i am now looking forn something that will NOT smoke and thought that the vent-free set was the way to go. not sure since # 9 above talks about soot.
Answer: The fact that your original gas logs smoked can indicate a few things. Because Peterson gas logs are pretty much the best you can buy, smoking is rarely a matter of the burner system or logs themselves, but rather something to do with the fireplace or the installation of the logs. In most cases, the logs are simply stacked too close together, which starves the gas for oxygen and causes incomplete combustion. A poorly drafting fireplace is the second most common problem. A vented gas log will not draft any better than a real wood fire, so if a fireplace smokes when a wood fire is burning, it will most likely smoke with a gas fire. If you have a see-thru fireplace or one that is open on 2 or more sides, it is common that drafting problems occur. Another cause of sooting from a gas log is that not all propane gas is the same quality. Some propane is simply dirty and will cause more sooting. Installing a vented gas log will drastically reduce sooting if the fireplace drafts poorly because the chimney will be closed and you are not dependent on draft. Ventless gas logs also have specific instructions on the placement of the logs so that they do not cause sooting either. However, if your propane gas is poor quality, some sooting may occur...but it will be far less than what you experienced from the vented log set. Keep in mind that you may still experience an odor from ventless gas logs, which is to be expected. Please feel free to call and talk to our gas log experts for more details about your particular situation.
Question: I want to place a gas log into an existing wood-burning masonary fireplace. I only have access to LP. One fireplace store told me I should only install a ventless unit because of the LP or I would have excessive sooting and unrealistic flame and fire. Another store told me it did not matter. My wife and I have a wood fire almost every night and really enjoy a fire and want the gas log to be as realistic as possible. Your thoughts and suggestions, please. Thank you
Answer: After being in the fireplace business for over 25 years and personally installing over 3,000 gas logs, I can say without a shadow of a doubt that "Vented" gas logs are going to be much more realistic in appearance than ventless logs. However, all vented gas logs will create some soot, just like burning real wood does. If they are properly sized and correctly installed, the sooting will be minimal and will not cause any problems because it will go up the flue just like a real wood fire. Some soot will always be present on the surface of the logs as well, which is to be expected and even adds to the realism. Ventless gas logs will provide more heat and will not create soot (if properly installed), but they are far less realistic. They also produce an odor that many people dislike or simply cannot handle, so ventless gas logs are only recommended if heat is the primary reason for thier use. Keep in mind that when you burn wood, soot is a natual part of the process. If your wood burning fireplace is not sooting up your house, then a vented gas log will not either.
Question: In addition to smell, how do propane logs differ from those burning natural gas? After two vented sets, we are really interested in the ventless type,
Answer: The biggest difference between natural gas and propane is the cost! In most parts of the country, natural gas is about 1/2 the cost of propane, so if you have access to both fuel types, natural gas is usually the logical choice, but you should check the difference in price. Natural gas is generally sold by the "Therm" where as propane can be sold by the gallon or pound. Ultimately, to compare the cost of both fuels, you will want to convert the unit of measure to BTUs. So, how much you pay per 1000 BTUs is what you want to consider.

Here are the BTU conversions for both gas types:
  • Natural Gas: 100000 BTUs per Therm
  • Propane: 91500 BTUs per Gallon
  • Propane: 22000 BTUs per Pound

Read more here about: The Cost to Burn Gas Logs

Otherwise, there is little difference between burning propane and natural gas when it comes to gas logs providing you have good quality propane. Natural gas is generally quite pure, whereas propane has less consistency in purity. So the quality of the fuel can vary quite a bit between suppliers. Propane that is less pure (dirty), will tend to produce more soot and smell. Also, propane burns nearly twice as hot as natural gas by volume, the ventless gas logs are ported differently for each fuel type, so they end up producing the same amount of heat. With vented gas logs, the BTUs may be different between natural gas and propane, but the natural gas models tend to burn hotter than the propane burners due to the way the burners are ported and the gas is regulated.
Question: I currently have a Napoleon gas fireplace insert. Its17 yrs old and the mercury switch went on it and I cannot find a replacement or bypass so instead of buying a whole new fireplace insert I thought that I could buy a gas log set and install it in the box myself. The fireplace has a 4" chimney and a blower. It this possible. The inside of the box is 13" by 30" Thanks
Answer: You cannot install gas logs into a gas fireplace insert. Gas logs are designed to be installed only in wood burning fireplaces, or in some cases, a ventless firebox that is factory approved for aftermarket ventless logs. Your Napoleon gas fireplace can only be used with the burner system and logs that it came with. There are no options to change it to burn anything else. The main limitation is the 4" B-Vent and the thin-walled construction of the firebox. Gas logs require a chimney and firebox that is capable of burning wood in order to draft properly and burn safely.

So, either you will need to find someone who is capable of repairing the fireplace, or replace the insert. You may be able to find a qualified service technician using the resources here on our website: Certified Fireplace Installers and Service Technicians.

BTW, the term "gas fireplace insert" refers to a gas appliance that is installed into a wood burning fireplace that converts it into a gas fireplace. Many people confuse this term with the term "Gas Fireplace", which is a completely different type of appliance. so I am not exactly sure which one you insert or a gas fireplace. Can you email me some pictures so I can see what you actually have and possibly offer more advice? Email to: