Gas fireplaces are often found installed within existing masonry fireplaces because they can be far more efficient than the open wood burning fireplace they replace.
Many gas fireplaces are able to utilise the existing chimney found as part of an open masonry fireplace, but do gas fireplaces need a chimney to be able to be installed and operated?
Natural vent gas fireplace inserts will require the use of a flue system, which can be installed within a chimney to facilitate installation of a natural vent gas fireplace. Direct vent and ventless forms of gas fireplaces do not need a chimney.
We have a natural vent gas fireplace in one of our of masonry fireplaces and it utilises the chimney to exhaust waste air, and we’ve recently removed a gas fireplace insert from another open fireplace that also required natural venting.
We’ve therefore put together this article using our own gas fireplaces as examples whether:
- Gas fireplaces need a chimney.
- You can put a gas fireplace in without a chimney.
This article discusses the use of a chimney in order to exhaust waste air from a gas fireplace from a home. For more information on venting requirements for gas fireplace covering supplying air to a gas fireplace see our article on whether gas fireplaces need venting.
Do Gas Fireplaces Need A Chimney?
Not all types of gas fireplaces will require the use of a chimney. Most gas fireplaces in the form of direct vent and ventless gas fireplaces can be installed in a home without a chimney, but natural vent gas fireplaces will need a chimney.
Whether a gas fireplace needs a chimney or not will depend on the type of gas fireplace.
Not all homes will have an existing masonry fireplace with attached chimney in which a gas fireplace can be installed. There are therefore other options available for gas fireplaces that don’t require the use of a chimney in order to facilitate their installation in a home.
As gas fireplace technology has progressed over recent years the requirement to have a chimney in order to be able to install and use a gas fireplace has become less common.
The main types of gas fireplace are:
- Natural vent (B-vent) gas fireplaces
- Direct vent (balanced flue) gas fireplaces
- Ventless (flueless) gas fireplaces
We’ve discussed these main types of gas fireplaces and their potential requirements for a chimney in more detail below.
Does A Natural Gas Fireplace Need A Chimney?
Natural vent gas fireplaces need a chimney in order to operate safely. Waste air from a natural B-vent gas fireplace installed within an existing masonry fireplace is exhausted out of a home through a chimney.
Natural vent gas fireplaces, also known as B-vent gas fireplaces, are types of gas fireplaces traditionally installed within existing open masonry fireplaces to convert them from a less efficient wood burning fireplace to a more efficient gas fireplace.
Natural vent gas fireplaces take air from inside a home to feed the flames.
B-vent gas fireplaces also need to remove waste air generated from the combustion of the gas in the gas fireplace. This is done through the existing chimney above the masonry fireplace in which the natural vent gas fireplace sits.
As an example, our gas fireplace is a natural vent gas fireplace.
It sits within the living room masonry fireplace and utilises the existing chimney to exhaust waste air from the fireplace when in use.
Waste air from the combustion of the gas inside this natural vent gas fireplace rises up through the hood opening at the top of the fireplace and up through the chimney.
A B-vent gas fireplace cannot be used without a suitable chimney in which to exhaust waste air.
We therefore couldn’t move our own natural vent gas fireplace to another location in our home unless it was into another open fireplace with chimney. If we wanted to be able to install and use a gas fireplace in another room in the house we would need to look at other types of gas fireplace, which we discuss further in this article.
Although our own particular chimney doesn’t have a damper, a damper would need to be open when using a natural B-vent gas fireplace. For more information see our guide on fireplace dampers.
Natural vent (B-vent) gas fireplaces therefore require the use of a chimney in order to operate safely but must be installed in line with the building codes and regulations for your particular area of residence.
Does A Direct Vent Gas Fireplace Need A Chimney?
A direct vent gas fireplace does not need a chimney. Direct vent gas fireplaces can vent directly through an external wall of a home or up through the roof and does not need to be sat within a masonry fireplace with chimney in order to do so.
Direct vent gas fireplaces differ to natural vent gas fireplace in that both the air used for combustion and the waste air from combustion of the gas is directly vented and exhausted to and from outside.
A direct vent gas fireplace does not need a chimney in order to achieve this and can therefore be installed in more locations around a home compared to what is possible with a traditional B-vent gas fireplace.
Common venting arrangements for direct vent gas fireplaces include a dual vent pipe out the back of the unit that goes horizontally through an external wall of a building, but the waste vent can also be placed higher up a wall or sent vertically through the roof if required.
Direct vent gas fireplaces are sealed systems and so the air to and from these gas fireplaces does not mix or interact with the air within a home.
If your home doesn’t have an existing masonry fireplace with chimney, you’re looking to install a gas fireplace in another room of your home that doesn’t have a chimney or want to keep your original open fireplace for wood burning purposes, a direct vent gas fireplace is a popular option.
Direct vent gas fireplaces therefore do not need a chimney in order to have one installed, but must be installed in accordance with your local building regulations and codes.
Do Ventless Gas Fireplaces Need A Chimney?
Ventless gas fireplaces do not need a chimney and do not need to directly vent fresh or waste air in or out of a home. A ventless gas fireplace burns the fuel cleanly enough for there to be no direct vent requirements.
Ventless gas fireplaces, also known as flueless gas fireplaces, differ from both natural vent and direct vent gas fireplaces in that they don’t need either a form of chimney or a direct form of vent in order to operate.
Whereas B-vent gas fireplaces will need to be installed within a masonry fireplace with chimney and direct vent gas fireplace with need dual external vents for both fresh and waste air, a ventless gas fireplace requires neither and will exhaust waste air back into the air within a home.
This is possible because ventless gas fireplaces burn the fuel cleanly enough for there to be a very minimal amount of waste by-products and so they are considered suitable for use in homes in many countries.
Even through ventless gas fireplaces don’t directly require a form of external vent or chimney, depending on your area of residence and specific codes and regulations, an external vent may be required somewhere in the same room as where the ventless gas fireplace is located, which you can find out more about in our article on whether gas fireplaces need to be vented.
A ventless gas fireplace isn’t restricted to a chimney like natural vent gas fireplaces or external wall venting like direct vent gas fireplaces and so are suitable for use in more locations around a home.
A ventless gas fireplace therefore also doesn’t require a chimney, but must be installed as per your local building regulations and codes, such as with additional external air vents within the room if required.
Can You Put In A Gas Fireplace Without A Chimney?
Direct vent gas fireplaces and ventless gas fireplaces can be put in a home without a chimney but may require their own form of venting such as through an external wall. Natural B-vent gas fireplaces cannot be put in without a chimney flue.