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In Which States Are Ventless Fireplaces Illegal?

In California, ventless fireplaces are completely illegal. However, some municipalities across the United States have also banned ventless fireplaces, and many states and districts have restrictions about how they can be used. So even if your state allows ventless fireplaces, you’ll need to check your local zoning laws.

After quite a bit of research, it seemed that California was the one and only state in which they were illegal. They were illegal in Massachusetts until recently but are legal now, and other states have restrictions on them but haven’t completely banned them. For example, in 2003 New Mexico passed a building code that only allowed ventless fireplaces to be used with liquid propane—not natural gas.

Additionally, everywhere in the United States has prohibited ventless fireplaces to be used or installed in HUD housing.

For more information, you can continue reading, and also consult this map. Also, don’t forget to check with your local zoning department to find out whether your municipality has additional restrictions.

But why are there any restrictions on ventless fireplaces? What’s the big deal here?

Let’s talk more about the details regarding the regulations, as well as the reasoning behind them—the potential dangers of ventless fireplaces—and any other alternatives you might have.

Why Are Ventless Fireplaces Illegal in Those States?

Ventless fireplaces are often restricted or illegal because of safety concerns, specifically due to the fact that they might introduce noxious combustion by-products into your home’s air supply. 

Because of their engineering, all of the gases that the fire releases go straight into your home—exactly none of the fumes go anywhere but into the room with the fireplace. 

On the one hand, this makes ventless fireplaces incredibly efficient. On the other hand, if any of the released fumes are poisonous or toxic to people, your ventless fireplace has become a huge danger.

Now you might be wondering, how can a fireplace that sends everything back into the home be allowed anywhere? Why would they even exist? How do they work?

How Do Ventless Fireplaces Work?

There are two main differences between a vented and a ventless fireplace—the intake vent and the exhaust vent.

On a traditional vented fireplace, fresh air comes into the fireplace through an intake vent, and all noxious fumes released during combustion (which, remember, is unavoidable—combustion is the whole point of the fireplace) leave via an exhaust vent.

But a ventless fireplace, as you might have guessed, has no intake vent and has no exhaust vent. Fresh air comes into the fireplace from the room, and post-combustion air is released out of the fireplace, into the room, through the same opening.

This setup has two advantages. Firstly, the fireplace operates at nearly 100% efficiency because all of the air that the fire heats releases into the room. None of the air gets vented out. Instead, 100% of your energy is used on warming air that will stay within your home.

Secondly, a ventless fireplace is easier to install in your home since there is no need for a flue. This results in fewer architectural restraints—your fireplace doesn’t need to have any access to the outside; it can be anywhere. A vented fireplace might cost $3,500 to $8,000 to install; a ventless fireplace might cost $1,000 to $5,000 to be professionally installed.

And as for any fumes that are released into the home, ventless fireplaces use some ingenious technology to keep you safe.

According to Allison A. Bailes of Energy Vanguard, during “perfect combustion”, oxygen molecules will combine with methane’s carbon and hydrogen, and the result (other than heat) will be H2O (aka water) and CO2 (aka carbon dioxide)—neither of which are poisonous.

The only trouble is when your fireplace isn’t getting enough oxygen. This can be caused by fans, candles, lack of fireplace maintenance, or even just a draft. When your fireplace doesn’t have enough oxygen, its combustion creates poisonous carbon monoxide.

To fight this, ventless fireplaces include built-in carbon monoxide detectors and oxygen detection sensors.

If carbon monoxide is detected in the home, the fireplace will automatically shut off. Similarly, if oxygen levels drop to an unsafe level, the fireplace will also be automatically shut off.

But if ventless fireplaces have these safety mechanisms built-in, then what’s the big deal? Why ban or even restrict them? Given what we just learned, aren’t ventless fireplaces perfectly safe?

Can Ventless Fireplaces Make You Sick?

On one side of this issue, the ventless fireplace industry says that ventless fireplaces are perfectly safe, so long as they are installed and used according to manufacturer instructions, “which is important for all home appliances.”

But on the other side of this issue, the American Lung Association has a pretty clear opinion: “Never use unvented appliances”, they say.

There are a few reasons that safety remains a concern for ventless fireplaces.

First of all, the ventless fireplace industry mentioned that not every fireplace owner follows the instructions in the letter. In a University of Illinois study of 30 homes equipped with ventless fireplaces, half of the homeowners didn’t follow the exact operating instructions of their fireplaces, and, as a result, the carbon monoxide levels of 20% of those homes were higher than what the EPA considers safe.

Additionally, many ventless fireplaces don’t come equipped with a carbon monoxide detector. Carbon monoxide is odorless and deadly. Without a detector, a person wouldn’t even know they were being poisoned.

And even among the models that do include carbon monoxide detectors, those detectors often aren’t enough. While the World Health Organization recommends no more than one hour of carbon monoxide (CO) exposure at concentrations of 26 ppm or more, the common Kidde CO detector won’t go off until ten hours of CO exposure at a concentration of 40 ppm. Most home CO detectors are built only to detect very high levels of carbon monoxide—so if your ventless fireplace is only poisoning you slowly, your detector won’t let you know.

According to people opposed to the use of ventless fireplaces, another risky gas emitted by them is, as strange as this might sound, water vapor. Now, what you’re probably thinking is correct: water is not poisonous to humans (not even to pets). But what is poisonous is mold, which this extra water vapor can cause. The vapor turns into water on cold surfaces in your home, and there, mold can grow. In addition to being a health risk, mold can damage clothes, books, and even the structure of your home.

However, the ventless fireplace industry says that the water vapor released by a ventless fireplace is not enough to cause mold, citing research that indicates that for 99% of US homes, ventless fireplaces don’t release enough water vapor to result in mold.

Some manufacturers recommend that you use your ventless fireplace with an open window. But then the efficiency of the ventless fireplace—one of its main advantages—literally goes out the window. Essentially, instead of a fireplace with a built-in, precise vent, you’ll be manually venting your whole room with the window.

Can Ventless Fireplaces Be Converted to Vented?

No, ventless fireplaces cannot be converted to vented. The two are completely different machines, and a ventless fireplace is not designed in a way that allows vents to be added to it.

All you can do is replace the ventless fireplace with a completely new, vented one. You can consider it an upgrade.

If you use unvented logs in a universal unvented fireplace, the logs might be reusable in a new vented fireplace.