Are Vent-Free Propane Gas Log Fireplaces Good or Bad?

Updated on September 15, 2019
John Dove profile image

John enjoys home improvement projects that improve the quality of home living.

image credit:   Dlvv |
image credit: Dlvv |

Fireplace Magic

There is something magical about sitting in front of the fireplace feeling the warmth of the fire's radiant heat and watching the dancing flames and glowing embers. It's cozy, and it's a welcome contrast to the bitter cold outside. It reminds us of happy memories and good times with family and friends.

Vent-Free Propane Gas Fireplace vs. Wood-Burning Fireplace

Vent-free, propane-gas fireplace sets can be an attractive alternative to burning wood. Consider the advantages:

  • Convenience: No more firewood to collect and store. No messy ashes left in the fireplace to remove. No fire-starting frustration.
  • Health: Burning wood produces gases, smoke, and small particulates. Hopefully, if the fireplace and chimney are working well, all this goes up the chimney. Unfortunately, some of these pollutants may find their way into your living space. This can exacerbate asthmatic conditions in some people, and possibly lead to respiratory ailments in others.
  • Cleanliness: Soot from these pollutants can settle on carpets and furniture.
  • Safety: A spark screen should be placed in front of the fire to prevent sparks from flying out onto floors and carpets. The fire must have the proper draft to draw pollutants up the chimney. The chimney needs periodic cleaning to remove creosote.
  • Environment: Gasses and pollutants from your wood fire leave the chimney and contribute to air pollution.

Advances in Propane Gas Log Fireplace Design

According to their manufacturers, advances in precision-engineered gas burners have allowed the design of vent-free firelog designs. They require no vent and no chimney. They are highly efficient: all the heat produced is released into the room to warm the air. No heat is lost up the chimney. In fact, a chimney is not required. You can seal up your chimney and save even more heat loss from your house.

Safety advances have been made in pilot light/thermocouple designs and oxygen sensors. If the thermocouple senses that a pilot light has gone out, it shuts off the gas. If the oxygen sensor senses that the room oxygen has dropped to a pre-set safety level, the gas is shut off.

The firelog design and materials are chosen so that the flames burn as cleanly as possible.

Other options available today are thermostatic and remote controls.

Propane gas is a clean-burning fuel. As long there is plenty of oxygen in the room with a propane gas firelog, the burning propane produces carbon dioxide (CO2), water (H2O) and heat. The amount of water produced is about 8 pounds (1 gallon) per 100,000 BTU's. A gas log fireplace burning at 25,000 BTU's per hour would add about a quart of water per hour to room air.

The added water vapor can be an advantage in cold winters when room humidity is extremely low. However, if the room humidity is high enough (about 70% relative humidity), the added water vapor from the burning propane will contribute to mold. Based on independent computer modeling studies the industry claims that only in Florida and along the Gulf Coast is this condition a possibility. For the rest of the U.S, the added water vapor is usually insufficient to cause mold, according to that study.

Vent-free gas heaters now come in a wide variety of designs that are attractive for any decor.

But, are they really safe?

Disadvantages of Vent-Free Propane Gas Firelogs

The room with the vent-free propane gas firelogs must have adequate oxygen and a source of fresh air to replenish the oxygen lost in combustion. That is why the size of the room must be taken into account when selecting the size of the firelog. That is also why it is usually recommended that a window be opened to allow fresh air.

If the propane combustion is not complete, the burn produces carbon monoxide and soot. That is why the firelog must have an oxygen sensor and why it is a good idea to install a carbon monoxide detector in the same room.

Soot produced from incomplete combustion can dirty wallpaper, curtains, and carpets.

Pollutants from incomplete combustion can be inhaled and lead to health issues.

All that is why the industry has worked to improve gas-burning technology so that there is complete combustion to the maximum extent. The industry says that today's vent-free fireplaces operate well within national standards and recommendations concerning these five byproducts of gas combustion: carbon monoxide, carbon dioxide, nitrogen dioxide, oxygen, and water vapor (humidity).

Is Vent-free Propane Gas Combustion Completely Safe?

Not everyone is totally convinced that vent-free combustion is completely safe. The American Lung Association recommends that gas firelogs be vented. ALA also argues against the use of wood-burning in fireplaces. Here are their recommendations:

  • "Declare your home a smokefree zone. Never let anyone smoke indoors." The admonition against "smokefree" includes smokers, but could be construed to include all sources of 'smoke.'
  • "Keep humidity levels under 50 percent." Note: According to InspectAPedia for Building & Environmental Inspection, Testing, Diagnosis, Repair, in order to avoid a mold and dust mite problem a "maximum indoor relative humidity of 55% RH may be acceptable, 50% RH better. . ."
  • "Avoid burning wood because it adds pollution indoors and out." That is their specific caution concerning wood-burning fireplaces and stoves.
  • "Make sure gas appliances vent completely to the outside. Do not use ventless stoves."
  • "Although both natural gas and propane stoves are much cleaner than their wood-burning alternatives, these devices must be directly vented outside the home to reduce exposure to carbon monoxide, nitrogen oxide and other emissions produced by these energy sources."

Some state and local codes in the U.S. prohibit unvented room heaters due to their inherent risks. The industry argues that these are unnecessary barriers to the use of modern, clean-burning vent-free gas heaters and fireplace log sets.

Finally, in the following video one experienced home inspector discusses vent-free gas heaters.

Home Inspector Discusses Ventless Gas Fireplaces and Heaters

Due Diligence Before You Buy a Vent-Free Propane Gas Log Fireplace Set

Bad Experiences With Ventless Gas Fireplaces: Testimonials by Users

Before you decide to install a vent-free gas log fireplace in your home, consider the experience of those who have actually used ventless set-ups. These experiences range from terrible health effects on family members to damage to interior walls and household furnishings.

If you are considering the purchase of a vent-free firelog unit, do your due diligence. Consider the pros and cons, and then:

  • Check with your local and/or state building code administration to see whether (1) a vent-free firelog unit is allowed in your home, and (2) if allowed, what standards govern its use
  • Consult with your dealer and be sure the unit you buy is fully compliant with applicable building code and ANSI standard Z21.11.02.
  • Make sure that it is properly installed
  • Make sure you understand and follow all safety precautions.
  • And make sure you know the risks associated with vent-free firelog units.

Dimplex Electric Fireplace Deluxe 23-Inch Insert, Black
Dimplex Electric Fireplace Deluxe 23-Inch Insert, Black
As for me and my wife, we would not go with vent-free gas fireplace systems. We chose this exact electric fireplace insert and installed it in our masonry fireplace. It has worked perfectly for years.

This article is accurate and true to the best of the author’s knowledge. Content is for informational or entertainment purposes only and does not substitute for personal counsel or professional advice in business, financial, legal, or technical matters.

© 2011 John Dove

What has been Your Experience with Vent-Free Propane Gas Fireplaces?

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    • profile image


      16 months ago

      Hey Jon, love the article very in depth. I agree without ventless gas can be dangerous if not installed correctly and overused. The added risk of moisture and mold is not good also.

      A great alternative you should consider would be an ethanol fireplace insert. They use eco-friendly fuel and have options safety sensors for extra safety. The benefit is they are easier to install and still give you real flames. I'd love it if you checked it out

      I know you mentioned you have an electric fireplace and those or great as well. Some people just prefer the look of real fire.



    • Azalea24 profile image

      Mercedus Long 

      23 months ago from Maryland

      One of the most important things people should remember is not to try and install these units themselves (unless qualified to do so). Installation of unit will require inspections by the county to ensure installation and operation.

      I agree with you that I would not choose a vent free unit. Primarily as they use the oxygen in the room and my boys have asthma.

      Great article. Looking forward to more


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