Where Can Gas Logs Be Installed?
Learn how to determine if you can burn gas logs in your fireplace.

Believe it or not...gas logs, are not safe to install in gas fireplaces (with few exceptions). Sounds odd, but it's quite true. Gas logs are actually made to be installed in wood burning fireplaces as a way of converting them to gas. They are not made to "spruce up" a poorly designed gas fireplace like those you see in many condos and apartments...and yes, maybe even in your home. Bottom line is, if you install a gas log in a gas fireplace that was not designed to accommodate them, you might end up asphyxiating yourself or burning your house down. So before you buy gas logs, you must know what type of fireplace you have...and if it is safe to burn gas logs in it. The information on this page will help you do just that.

VENTED GAS LOGS: Vented gas logs can be installed in most any fireplace that is fully capable of burning wood. Vented gas logs must be burned with the damper open. Vented gas logs can also be installed in outdoor fireplaces and fire pits that meet local building codes. You CANNOT install vented gas logs in any gas fireplace or gas stove including b-vent (natural vent), direct vent or ventless gas fireplaces. They MUST only be installed in an aproved fireplace that is fully capable of burning wood.

VENTLESS GAS LOGS: Ventless gas logs can be installed in any fireplace that is fully capable of burning wood and are burned with the damper closed. Ventless logs can also be installed in some approved ventless fireboxes, providing the firebox is specifically rated for the use of after-market ventless logs and does not have a specific proprietary ventless log and burner system supplied by the fireplace manufacturer. A ventless fireplace has no chimney, vent or damper. You CANNOT install ventless gas log in any other type of gas fireplace or gas stove including b-vent (natural vent), direct vent or ventless gas fireplaces. Important Note: Ventless gas logs are NOT legal in California and some other states, cities or municipalities. You must check with your local building department to see if they are legal in your area.

How do I know what type of fireplace I have and is it safe to burn gas logs in it?

You need to know if you have a wood burning or a fireplace that is only designed to burn gas. If it is a wood burning fireplace, then you can probably install gas logs in it. If it is not a wood burning fireplace, then you most likely CANNOT install gas logs in it (except for a few Ventless fireboxes as described below). If you do not know if you have a wood burning fireplace or not, the information on this page will help you make that determination, but first, look inside your fireplace to see if there are any metal parts aside from the damper. If there are, then it is probably some type of prefabricated fireplace. If that is the case, there should be a metal label with the brand name and model number located somewhere inside the fireplace. That label might also have some stipulations as to what you can burn in it. The label is usually somewhere near the opening, either on the sides (sometimes hidden by a mesh curtain) or on the upper front area just inside the opening. If you can find the label, try to Google the information on it to learn more about your fireplace. Often times you can find the owners manual online in a downloadable .pdf file. If you are still having difficulty determining what type of fireplace you have, just call us and we will help you figure it out. You can also take pictures of your fireplace and email them directly to me (the webmaster) at: gregt@hansenwholesale.com


Masonry Fireplaces:

Typical masonry firelace with a log lighter

Masonry fireplace with slate facing and gas log already installed

Masonry fireplace with brick chimney outside of house

Masonry chimney on roof top with 2 clay flue liners

Damper inside a masonry fireplace

OK for Vented Gas Logs
OK for Ventless Gas Logs

A typical masonry fireplace will have a hearth (firebox) and chimney that was built from scratch by a mason using some type of masonry. The inside of the fireplace will have special refractory bricks and the chimney outside the house will usually be made from brick as well, although it may be covered with stone or stucco. A "Tilt-up" fireplace that is made completely out of concrete and then tilted up to the house during construction would be considered equivalent to masonry fireplace. A masonry fireplace will usually have a heavy damper assembly with a long metal lever to open and close the damper (see picture). Although the chimney outside the house may be covered with stucco, stone, or any other building material, the actual inside if the chimney on a masonry fireplace is often lined with an oval shaped clay flue liner, although some older homes will have only brick. The flue liner or inside of the chimney of a masonry fireplace is usually rectangular or oval in shape and is normally 8" x 14" or larger (sometimes much larger). For larger size chimneys, there may be 2 or more flue liners (see picture left). It is rare that a masonry fireplace has a flue that is smaller than this, so if your flue is smaller, then you may not have a masonry fireplace. Don't be fooled into thinking you have a masonry fireplace just because there is brick or stone around the opening or covering the chimney outside...often times the brick or stone you see is simply decorative and has been applied over the face of a prefabricated gas or wood burning fireplace to make it look like a masonry fireplace.

Often times a masonry wood burning fireplace will have a gas line already installed with a log lighter attached to it (see picture left). The log lighter uses gas to start a real wood fire instead of using kindling. A log lighter is not an appropriate burner to be used with gas logs, but you can easily replace it with a gas log burner system.

If your damper is a wide rectangular piece that opens and closes with a lever and your fireplace is capable of burning wood, then you have a masonry wood burning fireplace and it will be capable of burning vented or ventless gas logs. Always have your chimney inspected before burning wood in your fireplace or installing a gas log. If you have been told that there are cracks in your chimney and it is not safe to burn wood, then you cannot safely burn a vented gas logs either because, just as with burning wood, the exhaust may get into the cracks and come into your home. In such cases, it may still be safe to burn a ventless gas log, but you must consult with a professional who is capable of inspecting your firebox and making the final determination.

Although ventless gas logs are ok to install in a masonry fireplace, they may not be legal to install in your municipality, so be sure to check with your local building department to make sure ventless gas logs are allowed.


Prefabricated Wood Burning Fireplaces:

Prefab fireplace with visible metal facing and refractory lining with a log lighter already installed.

Prefab fireplace with stone facing designed to make it look like a masonry firelace

Label Example inside a prefab wood burning fireplace

Typical prefab fireplace with 8" diameter round chimney and damper

Mosly OK for Vented Gas Logs
*May be OK for Ventless Gas Logs

A Prefabricated (or zero clearance) wood burning fireplace is a metal box that is lined with refractory panels and has a round metal chimney anywhere from 8" to 15" in diameter. The metal box and pipe are built-in to the home with 2x4 construction and the chimney outside the house is usually covered with stucco, siding, or sometimes brick veneer or stone. If you have a round damper that is 8" in diameter or larger and your fireplace is capable of burning wood, then you have a prefabricated wood burning fireplace.

Often times a prefabricated wood burning fireplace will have a gas line already installed with a log lighter attached to it (see picture left). The log lighter uses gas to start a real wood fire instead of using kindling. A log lighter is not an appropriate burner to be used with gas logs, but you can easily replace it with a gas log burner system.

If you have a prefabricated fireplace and want to determine what type of gas logs it can accomodate (if any), we suggest you first look at the installation manual. If you do not have a copy of the manual, find the model number of your fireplace and use google to find a .pdf copy...if it exists. The brand and model number should be stamped into a metal plate bradded to the fireplace somewhere near the opening on either side or at the top behind the mesh curtain (if you have one).

VENTED GAS LOGS: Prefabricated wood burning fireplaces can normally accommodate a vented gas log, which must be burned with the damper open. If the fireplace was designed to use vented gas logs, a gas line may already have been installed when the house was built. If there is no gas line installed, there will be knockouts for installing a gas line on either or both sides of the refractory liner inside the fireplace as well as in the sheet metal on the outside of the firebox, if in fact the fireplace was designed to be retrofitted with gas. If these knockouts do not exist, that suggests the manufacturer never intended to have a gas line run to the fireplace. If that is the case, you would need to find a copy of the installation manual to find out if any specific provisions are allowed for running a gas line to the fireplace. If you cannot locate a copy of the manual, we suggest that you do NOT install a gas log. FYI: Vented gas logs are usually referred to as a "Decorative Gas Appliance" in the installation manual and are not usually referred to as a gas log.

VENTLESS GAS LOGS: You may also be able to install a ventless gas log into a prefabricated fireplace depending on the manufacturer and model fireplace you have. You must check with the owners manual to determine if ventless gas logs are allowed in your fireplace model. If ventless gas logs are approved for your fireplace, the manual will say so explicitly and will state any limitations that are required...such as size or maximimum BTU. Ventless gas logs are often referred to as a vent-free heater or ventless heater in the owners manual. If the owners manual does not specifically state that you can install ventless gas logs, then you cannot install them.

If you are still having difficulty determining what type of fireplace you have, just call us and we will help you figure it out. You can also take pictures of your fireplace and email them directly to me (the webmaster) at: gregt@hansenwholesale.com


Ventless Fireplaces and Fireboxes:

NOT for Vented Gas Logs
*Maybe OK for Ventless Gas Logs

Ventless (or Vent Free) fireplaces are similar to prefabricated wood burning fireplaces in that they are a metal box that is framed into your house with 2x4s. The big difference is that there is no chimney at all. Most ventless fireplaces come with a factory installed gas log and burner system and you cannot change it without causing serious safety issues. However, there are some ventless fireboxes that are specifically designed to accommodate an after-market ventless gas log of any brand. If you have the latter type, then you can use any of the ventless logs on our site, but you must be sure to consult the owners manual of the fireplace to find out what the size and BTU limitations are because there usually are such stipulations set by the factory and exceeding them can create a potential fire hazard.

You cannot install vented gas logs in a ventless fireplace under any circumstances.

If you are still having difficulty determining what type of fireplace you have, just call us and we will help you figure it out. You can also take pictures of your fireplace and email them directly to me (the webmaster) at: gregt@hansenwholesale.com


B-Vent Gas Fireplaces:

Built-in burner system for a b-vent gas fireplace

NOT for Vented Gas Logs
NOT for Ventless Gas Logs

B-Vent (or Natural Vent) Gas Fireplaces are built-in to your home just like a prefabricated wood burning fireplace. Many people mistake a vented gas fireplace for a wood burning fireplace, so it is very important that you double check to make sure you know what type of fireplace you have. The first clue that a fireplace is a B-Vent fireplace is the diameter of the flue. If the flue exits from the top of the fireplace and is less than 8" in diameter, then it is either a B-Vent or Direct Vent gas fireplace. In either case, they are dealt with the same way (see direct vent fireplaces below). A few gas fireplaces will in fact have an 8" diameter flue, which happens to be the same diameter as the smallest flue used in some wood burning prefab fireplaces. So you if this is the case be sure to check the owners manual if you are not sure if it is a wood or gas only fireplace.

B-Vent cannot handle the heat produced by burning real wood or gas logs nor is it capable of exhausting all the fumes. B-Vent gas fireplaces will come with factory installed gas logs that cannot be modified or changed in any way. If you do not like the way your gas fireplace burns, you will need to replace the entire fireplace. Important Note: You cannot install any of the gas logs on our web site in this type of gas fireplace. Doing so creates an extreme safety hazard and can burn your house down!

If you are still having difficulty determining what type of fireplace you have, just call us and we will help you figure it out. You can also take pictures of your fireplace and email them directly to me (the webmaster) at: gregt@hansenwholesale.com


Direct Vent Gas Fireplaces:

Vent outside on the side of a house from a direct vent gas fireplace

Another direct vent termination outside a house

Direct vent fireplace where someone removed the glass front and burned the wrong type of gas logs.

NOT for Vented Gas Logs
NOT for Ventless Gas Logs

Direct Vent Gas Fireplaces are somewhat similar to B-Vent gas fireplaces except that the flue may be vented directly out the back and they have a sealed combustion chamber with a glass front that does not open. All direct vent gas fireplaces will come with factory installed gas logs that cannot be modified or changed in any way. If you do not like the way your direct vent gas fireplace burns, you will either need to replace the entire fireplace or contact the manufacturer to see if they have any available options for the logs. Important Note: You cannot install any of the gas logs on our web site in this type of vented gas fireplace. Doing so creates an extreme safety hazard.

If you are still having difficulty determining what type of fireplace you have, just call us and we will help you figure it out. You can also take pictures of your fireplace and email them directly to me (the webmaster) at: gregt@hansenwholesale.com


Wood and Gas Stoves:

NOT for Vented Gas Logs
NOT for Ventless Gas Logs

as logs cannot be installed in wood burning stoves or gas burning stoves. Wood stoves are designed to use far less air than wood burning fireplaces, so in most cases they have a 6" diameter vent that is not enough to properly exhaust the fumes given off by gas logs. Wood stoves generally tend to get hotter inside (because that is what they are designed to do) so the heat build-up can destroy the safety pilot assembly of a gas log. Wood stoves are also not tested and UL listed for use with gas logs, so not only will adding a gas log void the warranty of your stove (and gas log), if by chance the gas logs cause a fire and your home is damaged, it is possible that you will not be awarded any adjustment from your insurance company. Gas stoves are just like gas fireplaces in that they are designed only to accommodate the gas log and burner system that they come with from the factory. The venting systems are not designed to handle the heat of a gas log and cannot exhaust the fumes properly. Using any other gas log in a gas stove than the ones that came with it can create a fire hazard or potential explosion. Important Note: Bottom line for wood and gas stoves is...you cannot install gas logs in them unless the manufacturer offers such an option, in which case you can only use those made specifically for your particular stove.


More details

This information was copied over from another location on our website, so although it repeats much of what is said above, there are some other tidbits here that may help you if you are still unclear about anything above.

VENTED gas logs can ONLY be installed in a fireplace that is fully capable of burning wood. That means that the chimney must be in good condition. So if you want to burn gas logs because you had you chimney inspected and were told it was not safe to burn wood because it leaks or something, then it is not safe to burn gas logs either.

Ventless gas logs can only be installed in wood burning fireplace OR a factory built ventless firebox that is rated for use with after-market ventless logs. Every ventless firebox has LIMITATIONS to how many BTUs are allowed and how large a log set it can accommodate. If you have a factory built ventless firebox, you MUST refer to the installation manual to get this information before you can know what will work.

VENTED gas logs flat-out CANNOT be installed in any Gas only fireplace. Although this sounds strange, gas fireplaces are designed to accommodate ONLY the log and burner combinations designed specifically for the particular appliance. Vented gas logs produce far more exhaust and require more draft than a gas only fireplace is designed to accommodate. They also may produce more heat than the venting system is rated for. Vented gas logs are NOT rated to be used with B-Vent period!

VENTED and VENTLESS gas logs CANNOT be installed in any Direct Vent gas fireplace. Direct vent fireplaces are the ones that have a sealed glass front. These are even more finely tuned to work only with the logs that they come with and it is quite dangerous to install anything in them other than what the manufacturer supplied with the unit.

Neither vented or ventless gas logs can be installed in any Wood Stove! Most wood stoves do NOT have a large enough diameter chimney to create a proper draft for a gas log. Wood stoves operate at a very low draft, which is what makes them desirable and efficient. Also, most wood stoves made in the last 20 years are not designed to be burned with the doors open, so gas logs are not appropriate just for that reason alone. Also, wood stoves are designed to capture more heat inside the burning chamber, so a gas log set would OVERHEAT inside a wood stove. Those who believe that a ventless gas log can work in a wood stove would be incorrect because of this factor alone. It is also rare that you can find a gas log small enough to fit properly into a wood stove. Regardless, you cannot install a gas log in any wood burning stove.

Free standing wood burning fireplaces, most commonly manufactured by Malm, are treated just like a regular wood burning fireplace, so it is OK to install either vented or ventless gas logs in them if the fireplace and chimney is still in a condition that it is capable of burning wood.

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