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Vented Vs. Ventless Fireplaces: Pros and Cons

If you’re thinking of getting a gas fireplace, you’re probably considering whether you want to get a vented gas fireplace or a ventless gas fireplace. There are good reasons to go with either one and some reasons not to, depending on what you want to use a gas fireplace in your home for.

In general, vented fireplaces are better in terms of safety and function. However, most of the heat is lost through chimneys, so consider using a direct vent. Ventless fireplaces are still a great option and are safe when used properly. Check with your local laws first as some areas don’t allow ventless fireplaces.

While a controversy continues to rage about whether or not ventless gas fireplaces are safe, 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 a viable choice.

Continue reading to learn the facts. 

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What is the Difference Between Vented and Ventless Fireplaces?

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

  • Functionality: vented fireplaces have to be vented to the outside of the home, requiring either a chimney or a pipe to an exterior wall, whereas ventless fireplaces do not require venting to the outside of the home because they burn cleaner
  • Aesthetics: because vented fireplaces do not burn as clean as ventless, their flame looks more like the flame of a wood burning stove, whereas ventless fireplaces have more of a blue looking flame, like the flame of a gas range in a kitchen, so for some people they do not have a cozy appeal
  • Preference: because ventless fireplaces do not vent outside that means they produce a chemical smelling odor in the home that may be annoying or unpleasurable to some people

Vented fireplaces differ a little. There are natural vented fireplaces and direct vented fireplaces. Natural vented fireplaces pull air from the home and vent it outside through a chimney, much alike a wood burning fireplace. Direct vented fireplaces are sealed to the inside of the home and both pull air from and vent air to the outside.

Of course, both fireplaces function to produce heat and give the feel of a fireplace in the absence of a wood burning stove. But they each differ in how they are able to pull it off.

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

Are Ventless Fireplaces Safe?

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

That said, ventless fireplaces can cause these safety concerns:

  • Emission of fumes in the home
  • Depletion of oxygen
  • Increased chance of mold growth

Ventless fireplaces emit fumes into your home. Now what is also true is that those fumes contain safe levels of carbon monoxide, considerably more than vented fireplaces because they burn more cleanly.

Even so, it is a standard recommendation to not run your ventless fireplace for long periods of time and to crack a window.

Ventless fireplaces also tend to deplete oxygen, so it is best to bring in fresh air periodically. New ventless fireplaces come 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 do not keep track of it.

Are Ventless Fireplaces Legal?

While ventless fireplaces are legal in many states, they are banned in California and Massachusetts, and several other states dictate modifications on their use or they are abolished in certain cities within the state. Internationally, Canada as well as other countries have banned ventless gas fireplaces.

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

If they are banned then you will not be able to have them installed, and it’s not recommended to try to install this kind of unit on your own.

Vented vs Ventless Fireplaces: Pros and Cons

To make the two types of gas fireplaces a little easier to compare, below is a table with some pertinent facts set side by side. Here is a quick look at a vented vs. ventless fireplace stand up against each other. You may be surprised at the benefits and drawbacks of each:

Vented FireplaceVentless Fireplace
Average Cost to Install$3,500 – $8,000$1,000 – $5,000
Average Cost to RunNatural Gas $.52/hourNatural Gas $.25/hour
Which is Safer?Generally saferGenerally less safe
Better Heat OutputLess heat outputBetter heat output
Easier to InstallGenerally harder to installGenerally easier to install
Average Lifespan15-25 years15-25 years
Environmental RatingNot as energy efficientMore energy efficient

Cost to Install

Generally speaking vented fireplaces cost more to install than ventless for one simple reason. In most cases, if you don’t already have a chimney, you have to create a “vent” for the vented fireplace. That means creating a hole in your roof for a chimney or your wall for a wall vent.

Of course it is not as simple as it sounds. The hole in the roof has to navigate the ceiling, insulation and duct-work in the attic, as well as being to code for the county and the state.

A wall vent is sometimes an easier way to go, and as allowable thanks to the fact that a direct vented gas fireplace can have horizontal ventilation.

The one exception to this is if you already have a wood burning fireplace in your home, which would come with a chimney.

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

Average Monthly Cost to Run

It was probably clear from the data above that ventless fireplaces are cheaper to run than vented fireplaces. This is even true if you are using liquid propane. On average:

  • Liquid propane for a vented fireplace costs a little over $1 an hour
  • Liquid propane for a ventless fireplace costs $.50 an hour

The reason for this goes back to the way that a ventless fireplace burns gas. Because it allows fumes into the home it must burn the gas cleanly, which results in better energy efficiency and cheaper usage.

Which is Safer?

In a side by side comparison, vented fireplaces come out safer for the obvious reasons. Even clean as they are, ventless fireplaces allow enough carbon monoxide into a room that they are:

  • Recommended not to be used for long periods of time
  • Recommended not be used in bedrooms where the carbon monoxide can build up faster.

It is a matter of the very simple difference between the two fireplaces. One vents outside and one doesn’t. No matter how clean the fumes are, there will always be a degree of caution needed when using a ventless fireplace. That said, because of the other advantages, some people accept a degree of risk.

Which Has a Better Heat Output?

One of the other advantages ventless fireplaces have is that they create more heat than vented fireplaces precisely because they vent inside. When the fumes go outside the home, some of the heat goes with it.

By contrast, ventless fireplaces keep much of the heat in the home by venting that heat (and light smoke and fume) inside the home.

So with a degree of risk comes a cheaper and hotter fireplace. It is worth noting, however, that if you follow the guidelines and open a window periodically to let air into the home (thus replenishing oxygen in the structure), the cold air you let in might cool down the warm air the stove created.

Which is Easier to Install?

The ventless fireplace is also usually easier to install. Because it doesn’t vent outside, you do not need to create an opening for a chimney or for a wall vent, which is why vented gas fireplaces cost more to install.

Another benefit of the ventless fireplace in terms of installation is that it doesn’t need to be in a certain place of a room, such as an exterior wall or a place with specific roof access. You have a lot more leeway aesthetically as to where you can put the unit.

The only additional work that may need to be done is routing propane lines to the place where you want it to be installed. That may limit your choices if you do not want to add the additional expense of rerouting propane lines.

Also, both units need to 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 about 15-25 years as noted above. This is for both kinds of units. The variance probably accounts for how often and how well you use your fireplace. 

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

If your gas fireplace is sealed, it’s best to let professionals replace your logs.

  • For vented fireplaces, ceramic logs can last up to 10 years 
  • For ventless fireplaces, they tend to last between three to five years.

What is the Environmental Rating of Each?

Typically ventless fireplaces are considered better for the environment because they burn cleaner and do not release as much carbon dioxide into the air.

Vented fireplaces, on the other hand, do vent carbon dioxide outside the home, so they do not have to burn as cleanly. For that reason they tend not to be considered as environmentally friendly as ventless. To put it into percentage terms:

  • A vented fireplace burns with 85% efficiency
  • A ventless fireplace burns with nearly 100% efficiency.

Which is Better–Direct Vent or Ventless Gas Fireplaces?

As with so many things, when answering which item is better than the other, you have to know as much about what you want as about the differences between the two items. As much is true of vented versus ventless gas fireplaces. The big question to answer is if you are comfortable with ventless.

Remember that ventless fireplaces exhaust fumes that are within the safe levels for breathing. You simply have to know the limits of how long the fireplace can run before you should let in some fresh air.

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

But of the two choices, ventless fireplaces are the best heat source, so if you are looking for a cheaper source of heat, a ventless may be the way to go.

There are also other things to consider that may matter to you that a direct vent fireplace has. Being completely sealed to your home, it takes air from and vents air to the outside.

If you are looking for a fireplace to be a cozy and comfortable feature in your living room, a vented fireplace is going to be preferable. It doesn’t burn as clean so the flames look like the flames of a wood burning fireplace.

How to Know if Your Fireplace is Vented or Ventless

You should be told at the time of purchase whether your fireplace is vented or ventless. Because ventless fireplaces are banned in some areas, the distinction should be made very clear.

But maybe you have bought a home that has a gas fireplace and you do not really know for sure whether it is vented or ventless.

There are a couple ways to tell:

  • 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 vented fireplace, it will have a solid glass panel sealed to the front of the unit. This is because the air traffic going in and out of the fireplace is all going to and coming from the outside, so no exhaust comes into your home.

Another way to tell is to turn the fireplace on and look closely at how the flames interact with the logs. If it is a direct vented fireplace, the flames will surround the logs so as to look like the log is actually on fire.

But in a ventless fireplace, the flames cannot touch the logs, so they will look as though they are coming through gaps or holes in the logs.

Can a Ventless Gas Fireplace be Converted to Vented?

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

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

Sadly, it’s not a good option. Ventless fireplaces were not made to have vents. What that means is that their whole construction and way of burning is for the sole purpose of being ventless. So it isn’t a matter of simply connecting a pipe from the fireplace through the roof.

That really is only the start. If it could be done it would also involve sealing a glass panel to the front of a fireplace that was not made to be sealed. There is also the issue of how it burns. If you were changing it for aesthetic reasons, you still would not be able to put vented fireplace logs into the ventless fireplace.

The best and only way to change a ventless to a vented gas fireplace is to remove the ventless fireplace and have the vented fireplace installed in its place. That could cost between five and twenty grand or more.

Conclusion

If the decision is yours to make, then both vented and ventless gas fireplaces are viable options for your home. Keep the controversies surrounding the ventless fireplaces in context.

They are best used when used wisely and within the precautions that the manufacturers suggest. Do so and they may be a good source of heat for your home.

But for pure good looks, the vented fireplace is still the winner. A direct vented or naturally vented gas fireplace portrays the warmth of a real wood burning fire.

If you set up a fan system with a direct vented fireplace you can get a little more heat production out of them as you cozy up before your clean burning fire.

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