Vented Vs. Ventless Chimneys: Pros and Cons (2023)

When you are thinking of buying a gas fireplace, you are probably considering whether you want a vented gas fireplace or a ventless gas fireplace. There are good reasons to choose one of the two and a few reasons against, depending on what you plan to use a gas fireplace for in your home.

In general, vented fireplaces are better in terms of safety and function. However, most heat is lost through chimneys, so consider using direct venting. Open fireplaces are still a great option and are safe if used properly. Check with your local laws first as some areas do not allow ventless chimneys.

While a controversy rages on as to whether ventless gas fireplaces are safe or not, the fireplace industry continues to vouch for their safety (with some precautions), even though ventless fireplaces have been banned in some states and some countries. In most places, both are viable choices.

Read on to get the facts.

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What is the difference between ventilated and unventilated chimneys?

There are some important differences between vented fireplaces and ventless fireplaces. The first difference has to do with functionality, the second with aesthetics, and the third with preference:

  • Functionality:vented fireplaces must be vented to the outside of the home, which requires either a chimney or pipe to an outside wall, whereas vented fireplaces do not require venting to the outside of the home because they burn cleaner
  • Aesthetics:Because vented fireplaces don't burn as cleanly as vented fireplaces, their flame looks more like a wood-burning stove flame, while vented fireplaces have a blue-looking flame, more like the flame of a gas stove in a kitchen, so for some people they have no cozy appearance
  • Preference:Because ventless fireplaces do not vent to the outside, they create a chemical-smelling odor in the home that can be annoying or uncomfortable for some people

Ventilated fireplaces are a little different. There are naturally ventilated chimneys and directly ventilated chimneys. Naturally ventilated fireplaces draw air from the home and direct it outside through a chimney, much like a wood-burning fireplace. Direct vented fireplaces are sealed to the interior of the home, drawing air in from the outside and exhausting air outside.

Of course, both fireplaces work to generate heat and give the feel of a fireplace when there is no wood burning stove. But they each differ in how they do it.

Open fireplaces produce more heat than vented fireplaces, but vented fireplaces look better. The different strengths of the two types of devices will appeal to different people.

Are Ventless Fireplaces Safe?

Before considering whether ventless fireplaces are safe or not, it is important to note that all gas fireplaces could potentially beleakcarbon monoxide into your home. Clogged chimneys, cracked glass panes, old parts, or leaking gas lines can all be responsible for gas leaks from gas fireplaces.

However, flueless fireplaces can cause these safety concerns:

(Video) Vented or Ventless Gas Fireplace (which one is better?)

  • Emission of smoke in the apartment
  • lack of oxygen
  • Increased likelihood of mold growth

Ventless fireplaces emit smoke into your home. What is also true now is that these fumes contain safe levels of carbon monoxide, significantly more than vented fireplaces because they burn cleaner.

Despite this, it is a standard recommendation not to use your ventless fireplace for an extended period of time and to open a window.

Ventless fireplaces also tend to use up oxygen, so it's best to let fresh air in regularly. New ventless fireplaces are shipped with oxygen monitors to guard against this possibility.

Another safety concern is that ventless fireplaces can increase condensation in your home, which can lead to mold growth if you don't keep an eye on it.

Are ventless fireplaces legal?

While ventless fireplaces are legal in many states, they arebanned in California and Massachusetts, and several other states are dictating changes to their use or abolishing them in certain cities within the state. Internationally, Canada and other countries have banned ventless gas fireplaces.

If you live in the United States, be sure to check if ventless fireplaces are legal in your city. They may be allowed in your state, but your city or county may ban them within the limits of their jurisdiction.

If they are locked you cannot have them installed and it is not recommended to install this type of unit yourself.

Vented vs. Vented Chimneys: Pros and Cons

To help compare the two types of gas fireplaces a little better, below is a table with some relevant facts side by side. Here's a quick look at a vented vs. a vented fireplace pitted against each other. You will be surprised at the advantages and disadvantages of each:

Ventilated fireplaceChimney without vent
Average installation costs$3.500 – $8.000$1.000 – $5.000
Average running costsNatural gas $0.52/hourNatural gas $0.25/hour
What is safer?Generally saferGenerally less safe
Better thermal performanceLess heat outputBetter thermal performance
Easier to installGenerally more difficult to installGenerally easier to install
Average lifespan15-25 years15-25 years
environmental assessmentNot that energy efficientMore energy efficient

installation costs

In general, vented fireplaces cost more to install than ventless ones for one simple reason. If you don't already have a chimney, in most cases you will need to create an "opening" for the vented chimney. That means creating a hole in your roof for a chimney or in your wall for a wall vent.

Of course it's not as easy as it sounds. The hole in the roof must be navigated through the ceiling, insulation, and duct work in the attic and coded for the county and state.

A wall vent is sometimes an easier route and than permissible thanks to the fact that a direct vented gas fireplace can have horizontal venting.

The only exception is if you already have a wood-burning fireplace in your home that would be fitted with a chimney.

In this case, it may be cheaper to install your vented gas fireplace as an insert for the existing fireplace. That depends on the size of your existing chimney and the size of the vented chimney.

(Video) Gas Logs: Vented or Vent-Free? How To Tell The Difference, and Decide Which One You Need.

Average monthly running costs

From the above data it was probably clear that unvented fireplaces are cheaper to operate than vented fireplaces. This is true even when using liquid propane. On average:

  • Liquid propane for a vented fireplace costs a little over $1 an hour
  • Liquid propane for a ventless fireplace is $0.50 per hour

The reason for this goes back to the way an unvented fireplace burns gas. As exhaust fumes enter the home, the gas must be burned cleanly, resulting in better energy efficiency and lower consumption.

What is safer?

In a head-to-head comparison, ventilated fireplaces are safer for obvious reasons. As clean as they are, ventless fireplaces allow enough carbon monoxide into a space that they are:

  • Recommended not to be used for a long time
  • It is recommended not to be used in bedrooms where carbon monoxide can accumulate faster.

This is the very simple difference between the two fireplaces. One vents to the outside and the other does not. Regardless of how clean the fumes are, there is always a degree of caution when using a ventless fireplace. However, due to the other benefits, some people take some risk.

What has better thermal performance?

One of the other benefits of ventless fireplaces is that they produce more heat than vented fireplaces precisely because they vent inward. When the exhaust gases leave the house, some of the heat goes with them.

In contrast, ventless fireplaces keep much of the heat inside the home by directing that heat (and light smoke and vapor) into the home.

So with some risk comes a cheaper and hotter fireplace. However, it's worth noting that if you follow guidelines and regularly open a window to let air into the home (thus bringing oxygen to the structure), the cold air you let in cools the warm air that the furnace produces.

What is easier to install?

The ventless chimney is also usually easier to install. Because it doesn't vent to the outside, you don't need to create an opening for a chimney or wall vent, which is why vented gas fireplaces are more expensive to install.

Another benefit of the ventless fireplace in terms of installation is that it doesn't have to be in a specific location in a room, such as in the living room. B. on an outside wall or in a location with special roof access. You have a lot more aesthetic freedom as to where to place the device.

The only additional work that may need to be done is moving prop guides to the location where they are to be installed. This may limit your choices if you don't want to add the extra cost of propane line diversion.

Also, both units must be installed by a professional contractor. This is not the time for DIY.

What is the average lifespan of each?

The average lifespan of gas fireplaces is approx15-25 yearsas described above. This applies to both types of units. The variance probably explains how often and how well you use your fireplace.

What is a discrepancy with the fireplaces is the lifespan of their logs. Gas fireplaces used to be made of cement, but today they are more commonly made of ceramic, which lasts longer in high heat. But even they eventually fade and look less like logs and more like ceramics and therefore need to be replaced.

(Video) Are Vent Free Fireplaces Dangerous? - eFireplaceStore

If your gas fireplace is sealed, it's best to have your logs replaced by professionals.

  • In vented fireplaces, ceramic logs can last up to 10 years
  • Ventless fireplaces typically last between three and five years.

What is the environmental rating of each?

Typically, ventless fireplaces are considered better for the environment because they burn cleaner and don't release as much carbon dioxide into the air.

Vented fireplaces, on the other hand, vent carbon dioxide outside of the home, so they don't have to burn as cleanly. Because of this, they tend not to be considered as environmentally friendly as ventless. To express it as a percentage:

  • A ventilated fireplace burns at 85% efficiency
  • A ventless fireplace burns with almost 100% efficiency.

Which is better - gas fireplaces with direct vent or no vent?

As with so many things, answering which item is better than the other requires knowing as much about what you want as you do about the differences between the two items. The same is true for vented versus vented gas fireplaces. The big question to answer is whether you're comfortable with ventless.

Remember that flueless fireplaces discharge exhaust gases that are within safe levels for breathing. You just have to know the limits of how long the fireplace can run before you should let in fresh air.

Another consideration is that theOdorcan be off-putting and also irritating to someone with allergies or asthma.

But of the two options, ventless fireplaces are the best source of heat. So if you're looking for a cheaper heat source, a ventless fireplace might be the way to go.

There are also other things to consider that might be important to you that a direct vent fireplace has. Because it's completely sealed to your house, it's taking out airandvents airtothe outside.

If you are looking for a fireplace that will be a cozy and comfortable element in your living room, a ventilated fireplace is preferable. It doesn't burn as cleanly, making the flames look like the flames of a wood-burning fireplace.

How to tell if your chimney is vented or unvented

When purchasing, you should be told whether your fireplace is vented or vented. Since ventless fireplaces are banned in some areas, the distinction should be made very clear.

But maybe you bought a home that has a gas fireplace and you're not sure if it's vented or ventless.

There are a couple of ways to say this:

  • Look for a sealed piece of glass over the front of the fireplace, or
  • Look at how the flames are in the fireplace

If it is a direct ventilated fireplace it will have a solid glass panel sealed to the front of the unit. This is because all air traffic going in and out of the chimney goes out and comes in from the outside, so no exhaust fumes enter your home.

(Video) Direct Vent vs Ventless Gas Fireplaces | What's the Difference?

Another way to tell is to turn on the fireplace and watch closely as the flames interact with the logs. If it's a direct-draught fireplace, the flames surround the logs, making it appear as if the log is actually burning.

But in a flueless fireplace, the flames cannot touch the logs, making it appear as if they are coming through gaps or holes in the logs.

Can a vented gas fireplace be converted to a vented one?

If you have a ventless gas fireplace and either regret buying it or regretting that it was in the home you bought, you may be wondering if you can convert it to a vented fireplace.

It sounds like a reasonable idea. It's a chimney, just cut a hole in the top, attach a pipe and stick it through the roof, right?

Unfortunately, it's not a good option. Fireplaces without vents were not made with vents. This means that their entire construction and manner of firing is for the sole purpose of having no vents. So it's not about simply running a pipe from the chimney through the roof.

This is really just the beginning. If it were possible it would also involve sealing a pane of glass at the front of a chimney that was not made to be sealed. There is also the question of how it burns. If you were to change it for aesthetic reasons, you still wouldn't be able to put vented logs in the flueless fireplace.

The best and only way to convert a ventless to a vented gas fireplace is to remove the ventless chimney and install the vented chimney in its place. That could cost anywhere from five grand to twenty grand or more.


If you have to make the decision, then both vented and unvented gas fireplaces are viable options for your home. Keep the flueless controversies in context.

They are best used when used with caution and within the precautions suggested by the manufacturers. If you do, they can be a good source of heat for your home.

But for pure looks, the ventilated fireplace is still the winner. A directly vented or naturally vented gas fireplace represents the warmth of a real wood fire.

If you set one upfan systemWith a directly ventilated fireplace, you can get a little more warmth out of them while you curl up in front of your clean burning fire.


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