Do Gas Fireplaces Need a Chimney?

We currently have a gas fireplace with a chimney, but as we’re looking at moving, we’re wondering if chimneys are really necessary. After all, wouldn’t it be easier to install a vent if you needed it? We did some research to find out. Here’s what we found.

A gas fireplace does not need a chimney. There are two main options to choose from, either a vented or ventless gas fireplace. Vented options are safer because they remove toxic fumes from the home and do not deplete the oxygen inside. For either option, you do not need a traditional chimney.

Let’s take a closer look at how gas fireplace ventilation works, the different types of vents, and how to maintain the vents.

By the way, if you’re interested in checking out the best fireplace starters and accessories, you can find them on this page on Amazon.

Can You Install a Gas Fireplace without a Chimney?

You can install a gas fireplace without a chimney if you have either a ventless gas fireplace or you install a venting system. For gas fireplaces that need a vent, a direct vent system is widely suggested. Direct vents can be installed either vertically through the roof, or horizontally through the wall.

Most gas fireplaces will rely on a venting system to help keep the home safe and to make sure carbon dioxide (and carbon monoxide) doesn’t get into the home. If you’re planning to put in a gas fireplace, think about what venting system would work best in your situation.

Here are some examples:

• If you have a chimney: you can simply run the vent up the chimney.
• If you don’t have a chimney: you can add a pipe (either vertical or horizontally, through the wall) that funnels the fumes outside.
• You can also choose a ventless gas fireplace if you do not have a chimney and want to keep costs down.

So, overall, gas fireplaces don’t need a chimney to work. You can hook up the gas fireplace to your chimney and place the venting through that if your home already has one. It is not required for you to build a brand new chimney to use a gas fireplace. 

What Kind of Chimney Does a Gas Fireplace Need?

Whether you choose the vented options or ventless, a chimney is not required for gas fireplaces. If you do choose to go with a chimney to help vent the gas fireplace, then the one already found in your home should be fine.

When using your chimney for a gas fireplace, remember:

• Check to see if the chimney is big enough to vent the gas fireplace you want
• Clean out the chimney before using it
• Set up a regular maintenance schedule to make sure condensation does not buildup

If you don’t have an existing chimney, it’s usually best to look into alternative venting options for your gas fireplace, such as direct vents (more on this later).

Do Gas Fireplaces Need a Chimney Sweep?

Unlike a traditional chimney, gas fireplaces, even the ones connected to a chimney, will not need a full chimney sweep. This type of fireplace does not have much smoke at all (if any) from burning the concrete logs, and won’t create too much of a mess. However, it is still important to check the chimney as recommended.

The biggest threat you may find with a gas fireplace is condensation in the chimney. Damp patches can stay there and may seep through to the walls or ceilings, causing damage inside. Servicing your gas fireplace can help check the chimney and other parts for issues including:

• Checking for cracks in the chimney
• Confirming the glass integrity
• Checking the deterioration of the fake logs
• Inspecting the gas ignition to see if it works
• Vacuuming the interior to keep it clean
• Checking the carbon monoxide detectors still work

The inspection should be done at least once a year, especially if you have the gas fireplace turned off for part of the year. These inspections will keep your home safe while using the fireplace.

If you’d to know where to start with fireplace inspections, you can visit the National Fireplace Institute and csia.org.

Do Gas Fireplaces Need to Be Vented?

Not all gas fireplaces need to be vented. There are some ventless models, but they’re decreasing in popularity due to safety concerns and bans in certain states such as California and Massachusetts, as well as Canada. However, most do need to be vented to help funnel the fumes out and keep the air safe in your home.

Update: it seems that Massachusetts may have reversed the ban on ventless gas fireplaces, but they are still banned in California. If you’re currently living in California, I wrote a post that you might find helpful. See: using fireplaces in California.

Ventless gas fireplaces do exist and can be installed in modern homes, but several safety concerns should be addressed:

• Only a certified ventless fireplace should be installed. If the fireplace was designed to use a vent, it must be vented.
• The fireplace should never be run without someone home.
• A carbon monoxide detector should be placed in the room with the fireplace. Burning gas releases CO, which is a deadly and silent killer.
• You should know the signs and symptoms of carbon monoxide poisoning, including dizziness, nausea, and falling unconscious.

When it comes to using a vent, there are several methods you can use to help keep your home safe. These include:

• Direct vent fireplaces
• B vent (natural) fireplaces

Both of these are seen as a safer alternative to using a ventless fireplace in your home. Let’s look at how each one works.

Direct Vent Fireplaces

Direct vents specialize in keeping the fire’s fumes separated from the indoor air. They achieve this with two separate chambers. One chamber is for circulating the indoor air around the fireplace, while the other expels the fumes outside.

Additionally, direct vent fireplaces draw in air from the outside instead of inside the home. Not only does this help keep things separated, but you no longer need a draft to keep your fireplace running.

For traditional fireplaces with chimneys, this usually means you need to crack a window open to replace the oxygen in the house. On colder days, this can be ineffective and create more cold air in the home than you’d like.

Additionally, direct vents with horizontal vents keep even more of the heat than vertical (since heat rises, it’s less likely to move horizontally). Horizontal direct vents can also be easier to install since you’re working with a wall and not the roof.

If you’d like to see a direct vent fireplace installation in action, check out this video by HandyDadTV.

B-Vent (Natural) Fireplaces

A natural vent works with a chimney or with a pipe venting system install through your roof. The pipe system allows you to remove the fumes from the gas fireplace without the costs of adding a chimney to your home. 

As previously mentioned, natural fireplaces need to draw the indoor air to fuel the fire. This air then needs to be replaced. If not, carbon dioxide can build up in the home. So you’ll usually need to create a draft from somewhere in the home, such as opening a window.

Unfortunately, with natural ventilation, the majority of the heat is lost as it’s vented along with the fire’s fumes. With wood-burning fireplaces and chimneys, this can mean up to 90% heat loss.

Lastly, if you have a natural vent, make sure that the damper is open when you’re running the fireplace so the fumes aren’t circulating back into the house.

In summary, natural venting isn’t nearly as great as direct venting when it comes to heat efficiency and maintaining healthy air quality. These two reasons are why direct ventilation is the preferred method of gas ventilation.

Ventless Fireplaces

Another option is to not use a vent at all and go vent-free. With this method, you can install your fireplace anywhere you would like inside your home. This makes it easier to get the fireplace you want, without all the mess. 

With a vent-free fireplace, you can do the installation without:

• A chimney
• Any type of piping system
• An external venting system

However, with this method, the pollutants will stay in the same room as the fireplace. On the other hand, most manufacturers who design these have strict safety regulations to follow. 

All of these machines have oxygen sensors available. The fireplace will turn off if it notices the oxygen levels are not safe in that room. The products used in a vent-free system are also clean burning so there are fewer harmful chemicals used compared to a traditional gas fireplace. 

If you choose to use a ventless fireplace, you should use some extra caution. Even though these fireplaces are meant to meet certain safety standards before they can be sold, there are still some risks to using a ventless gas fireplace. 

Some the issues with ventless fireplaces include:

• Depletion of oxygen: The process is slow, but the ventless gas fireplace can use up oxygen in the room. Only use it for short bursts and supplement with a central heating unit.
• Buildup of carbon monoxide: All gas fireplaces, including ventless, release exhaust fumes into the air. Again, using it for too long isn’t recommended. 
• Fire: Allowing the gas fireplace to overheat can trigger a fire. To help prevent this, have the fireplace and its components maintained once a year.
• Mold from moisture: These ventless fireplaces can produce heat and water vapor. Without proper cleaning, it may introduce mold into the home.

In summary, ventless gas fireplaces should be used on a limited basis. If you’re going to be purchasing a ventless fireplace make sure it’s a certified model and follow its runtime instructions. Additionally, cleaning and maintaining the fireplace will help avoid fire and mold issues.

Sources

• Chimney Sweeping – Do I Need to Sweep My Gas Fireplace? (restorationmasterfinder.com)
• 5 Common Safety Issues Associated With Ventless Gas Fireplaces | DoItYourself.com