Do Gas Fireplaces Need to Be Vented?

When I was first shopping around for gas fireplaces, I wasn’t sure if I had to install a vent for it. After all, that’s either a lot of money or work, and I wanted to weigh my options before deciding. So I did some research to find out – do gas fireplaces need to be vented?

Gas fireplaces need to be vented by a chimney or other vent, unless you have a ventless gas fireplace. Ventless gas fireplaces do not need ventilation and are designed to burn cleaner with a lower flame that will not smoke. If your gas fireplace is not a ventless model, then it will likely need a vent of some sort.

First, knowing a few more details between vented and ventless fireplaces can help you to decide if you need to install a vent in your home. Here’s everything you need to know.

Vented Gas Fireplaces: Pros and Cons

Pros

• Larger flames
• More realistic
• Less fumes

First off, the temperature of vented fireplaces is higher and more controlled due to the increased airflow from the vent. This also results in showing more realistic flames that are similar to that of a traditional wood-burning fire. 

Also, because vented gas fireplaces have a vent or chimney, the fumes are funneled upward and not into the house (assuming you have the damper open). This means you don’t really need a C02 or carbon monoxide detector, although it’s always a good idea to have one just in case.

But aside from these perks, there are also some disadvantages to owning a vented fireplace.

Cons

• Heat loss
• Yearly chimney (or vent) inspection and cleaning
• Higher gas bill

The biggest con of using a vented fireplace is heat loss. Heat naturally rises, and when the fumes head up the chimney, so does a lot of the heat. Gas fireplaces can still put out a lot of heat to warm a room, it just won’t be as fuel-efficient as ventless fireplaces.

Another disadvantage of vented gas fireplaces is chimney or vent maintenance. Generally, chimneys and vents need to be inspected and/or cleaned at least once a year. This will help prevent buildup or blockages in the ventilation and greatly reduce the risk of fires. It’s also a good idea to get the fan, thermostat, pilot light, and other components inspected yearly.

Lastly, due to the heat loss through chimneys, vented gas fireplaces can lead to a higher gas bill than their ventless counterpart. However, some would argue that the heat loss is worth it as much of the fumes are also funneled up the chimney.

A solution to this is getting a direct vent fireplace. Not only is much of the heat funneled into the house, but the fumes are kept in a separate chamber and expelled through a vent outdoors (more on direct vents later).

If you’d like an idea of where to start with fireplace inspections, you can visit the National Fireplace Institute for guidance and professionals. To locate certified chimney professionals, you can visit csia.org.

Now, onto ventless gas fireplaces.

Ventless Gas Fireplaces: Pros and Cons

Pros:

• Cheaper to install
• More heat efficient
• Has an ODS (Oxygen Depletion Sensor)

Overall, ventless gas fireplaces are a viable option and can still heat your room or home. Generally, ventless fireplaces are cheaper to install (and run) as they cost about half of the price of vented fireplaces.

Not only that, but they have a built-in ODS which shuts off the fireplace if too much carbon dioxide and monoxide levels were to rise above safe levels.

While ventless fireplaces do have their pros, they also have a few cons which make them questionable when compared to vented fireplaces.

Cons:

• Less visually-appealing fire
• Increased humidity and mold
• Releases some fumes
• Illegal in some areas

A minor drawback is that due to the decreased airflow, and risk of fume buildup, the flames are smaller and generally give off less heat. While ventless fireplaces can heat up a room on occasion, they’re not meant to run for a long time or replace a central heating unit.

Lastly, ventless fireplaces commonly produce some carbon monoxide and water vapor. Higher amounts of water vapor lead to more humidity, which can mean a greater chance of mold growth in the home.

Are Ventless Gas Fireplaces Safe?

The safety of ventless fireplaces is widely debated. While there is a small volume of fumes and by-products that enter the home, some associations and states have advised against using these fireplaces. Among these are the American Lung Association, Mayo Clinic, EPA, and the CDC as well as California and Massachusetts.

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.

One of the biggest drawbacks to ventless fireplaces is that they’ve been shown to release a small volume of fumes into the house. This is generally expected since there isn’t a vent. However, it has posed a safety risk and has been banned in several states as well as Canada.

Among those who advise against ventless fireplaces and the fumes it creates are the American Lung Association, Mayo Clinic, Environmental Protection Agency (EPA), and Centers for Disease Control (CDC).

So, while you might be able to buy ventless gas fireplaces in your area, consider doing more research on their safety first, or at least installing an extra C02 and carbon monoxide sensor.

Can You Convert a Ventless Gas Fireplace to Vented?

While it is possible to install vents in a ventless gas fireplace, it is not recommended. There are multiple safety and construction challenges that can arise, which can make it more difficult than simply installing a new, already vented fireplace.

If you’re looking to upgrade your ventilation, one of the best types to consider is direct vent. Direct vent fireplaces provide a great amount of efficiency and safety without the large construction project of a chimney. Most times it can be installed horizontally through a wall.

However, there are many other variables that go into converting ventless fireplaces to vent, and generally, the cons outweigh the pros.

For best results, speak to a fireplace dealer or installer about your current setup and situation. They’ll be able to give you a more detailed answer about ventilation after looking over your fireplace and its placement in the house.

How to Vent Fireplaces Without a Chimney

Direct Vent

Direct vents are sealed systems that circulate the cooler indoor air around the fire and expel clean, warm air. Because it’s routed through a separate chamber in the fireplace, the indoor air never comes in contact with the fumes or the outdoor air.

Instead, direct vents draw the air the fire needs for fuel from the outside. They also funnel 100% of the fire’s exhaust outside the home.

Typically, direct vents have one vent with two chambers. One of the chambers takes in air from the outside, while the other chamber vents the fumes outside.

The majority of direct vents are installed through walls horizontally, but some can be vertical, or have a top vent.

Natural Vent

On the other hand, natural vents are what most traditional fireplaces use. These types of fireplaces usually have doors that open or no doors at all. The air to fuel the fire is drawn from the indoor air, which is then funneled with the exhaust up a chimney or vent.

Since heat naturally rises, fireplaces with natural venting, especially wood-burning fireplaces, can lose up to 90% of the heat.

The biggest downside to natural venting is this heat loss, as you’ll likely need to run your furnace alongside the fireplace since much of the indoor air is being lost.

Not only that but because the indoor air is being drawn to fuel the fire, you may need to slightly crack open a window to add oxygen back into the home. Depending on the outside temperature, this can be counterintuitive to how well your home stays heated.

Final Thoughts

When it came to my search about if gas fireplaces needed a vent, I found that direct vent fireplaces were the best choice. These fireplaces are generally a safer bet as they don’t use indoor air to fuel the fire, only the outdoor air.

Whether you’re looking at a vented or ventless fireplace, decide based on the safety features you want as well as how difficult it is to install a vent in your home.

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