Why Do Some States Ban Vent-Free Gas Fireplaces?

In most places in the US when you’re looking to build a new fireplace or update an existing masonry fireplace, you have the option to use a vent-free, or ventless, gas fireplace. Vent-free gas fireplaces are high efficiency and characterized by their lack of chimney or other ventilation. In fact, according to a paper from the Journal of the Air & Waste Management Association, nearly 23 million consumers use vent-free gas heating products. So, who bans vent-free gas fireplaces, and why?

Currently only the state of California has a complete ban against these fireplaces, with states like Massachusetts having recently removed their bans. So, these fireplaces are permitted in 49 states, with some states having more restrictions than others. Even then, every county has different codes, so what is permitted in one city may not be permitted in a city just down the road. It’s important to check with your county’s building standards on what is and is not approved for use in your home or business. In this article we’ll discuss perspectives arguing for the vent-free fireplace ban, as well as against it, to ensure you can make the best-informed decision for your specific needs.


The Case For Vent-Free Gas Fireplaces

The number one benefit of vent-free fireplaces is their improved efficiency compared to vented options, with vent-free reaching up to 99%. This higher rate of efficiency is achieved by complete, or perfect, combustion and retaining of heat within your home.

Complete combustion consumes the perfect ratio of oxygen and fuel to produce relatively harmless byproducts—heat, carbon dioxide (CO2), water vapor (H20), and nitrogen (N). Water vapor is of course entirely harmless to us (and ANSI certified burners do not create enough humidity for mold or mildew to grow in your home), and low levels of carbon dioxide and nitrogen are harmless as well. In fact, the air we breathe is made of approximately 20% oxygen and 80% nitrogen, with around 0.04% of air being carbon dioxide.

Pro Tip: If you’re looking to use vent-free, regardless of if it is required by your county’s codes, we highly recommend purchasing an ANSI certified unit, which will always include additional safety features such as an oxygen depletion sensor (ODS).

Vent-free gas fireplaces don't require expensive masonry chimneys, or any other venting system.

Because vent-free fireplaces do not use any chimneys or similar venting solutions, they have no connection to the outside, meaning that all the heat that the combustion creates is released directly into your room. You have minimal heat loss in this scenario. If you’ve ever been seated near a door on a chilly winter day, then you’ve experienced bone-chilling draft when that door opens. Leaving the door closed sounds a lot warmer, doesn’t it?

Another benefit of vent-free fireplaces is their ease, and low cost, of installation. Because these fireplaces don’t require any ventilation, you have a lot more flexibility on where you can install them within your home. And no ventilation means you spend less on materials for that installation. An additional plus for these fireplaces, and any gas fireplaces for that matter, is no ashes to clean up. Unlike wood burning fireplaces that use a solid fuel, gas fuel leaves no charred remains behind for you to deal with.


The Case Against Vent-Free Gas Fireplaces

We’ve discussed how efficient vent-free gas fireplaces can be when they accomplish complete combustion, but we also need to discuss what occurs when the combustion is incomplete.

Incomplete combustion occurs when there is either too little oxygen, or too much, within the air in your room. When there is less oxygen to participate in combustion, the byproduct carbon dioxide (CO2) changes to carbon monoxide (CO). Similarly, if there is too much oxygen in the combustion, you will be left with nitrogen oxide (NOx) instead of just nitrogen (N).

Carbon monoxide is an odorless, colorless, tasteless, and combustible gas that is dangerous and highly toxic. When breathed in, this gas reduces the oxygen your cells receive. Effects vary based on intensity and duration of exposure, but high levels of CO do cause cell suffocation and can lead to death. Nitrogen oxide is similar although not necessarily as dangerous. NOx primarily effects your lungs, and short or small dosage exposures are likely to cause temporary, general problems such as cough. Prolonged or high levels of exposure can cause significant damage to the lungs, with death possible in extreme cases. It is these two dangerous gases that have caused California to outright ban vent-free gas fireplaces, and why so many other states and counties have restrictions on them.

Both byproducts are a very serious concern, and absolutely something you need to consider when selecting the right fireplace for your home. It is for this very reason we so highly recommend only purchasing ANSI certified vent-free systems.

Real Fyre vent-free systems are ANSI certified, and a popular brand among vent-free customers.

These certified systems include an oxygen depletion sensor (ODS), which shuts off the gas if the oxygen level drops below what is considered safe. With the average oxygen concentration in the air at 20%, and these ODS systems set to trigger at 18%, there is little opportunity for the oxygen to drop to a level that will cause any harm.

Additionally, all burners that are ANSI certified go through rigorous testing to ensure the levels of any dangerous byproducts are exceptionally low. This paper from the Journal of the Air & Waste Management Association states it most clearly:

“Currently, no evidence exists in the peer-reviewed scientific literature to indicate that vent-free gas heating products manufactured in accordance with current ANSI codes and maintained according to the manufacturer’s instructions are the cause of any health-related issues in the home from normal anticipated emissions. Nor is there evidence that the small amounts of carbon dioxide, carbon monoxide, or nitrogen dioxide produced as normal combustion products from ANSI code-compliant vent-free gas heating appliances exceed applicable standards for indoor environments.”

The arguments against vent-free gas fireplaces are only valid when discussing non-ANSI certified burners, and we absolutely agree that those can pose a risk. When installed and maintained in accordance with the owner’s manual, ANSI certified vent-free gas fireplaces are unlikely to put you or your loved ones in danger. If you are looking at installing a vent-free fireplace in your home of business, do make sure it’s an ANSI certified one.


The Best Choice for Your Home

At the end of the day, vent-free gas fireplaces do have more risk associated with them than their vented counterparts—though even vented fireplaces still have some risk. However, utilizing only ANSI certified vent-free burners, and complying with the manufacturer’s instructions on installation and maintenance do significantly reduce the risks. Even better if you ensure your home or business is also equipped with a carbon monoxide detector. We still wholeheartedly support gas fireplaces, both vented and vent-free, as a viable supplemental heating solution. But do make sure you purchase ANSI certified for vent-free.

We’ve outlined the arguments for and against vent-free burners, but understand that these decisions are important, and want to ensure that you’re completely confident in your choice. Once you’ve done some more research, or if you just want to ask us some additional questions, we’re happy to assist you in any way we can. You can reach our NFI certified team by phone at 866-578-8538, via live chat on our site, or by filling out our contact us form.


Sources + Additional Reading

Probabilistic Assessment of the Potential Indoor Air Impacts of Vent-Free Gas Heating Appliances in Energy-Efficient Homes in the United States, Journal of the Air & Waste Management Association

Vent Free Gas Fireplaces: Are They Safe?

ANSI Z21.1.2-2016 - Gas-Fired Room Heaters, Volume II, Unvented Room Heaters


Main Image: Dog relaxes in front of a vent-free gas fireplace.


Emily Lozano