Gas Fireplaces: Vented vs Vent-Free (or Unvented)

Are you thinking of adding a new gas fireplace to your Salt Lake City home? Well, you have a lot of options to choose from!

Is a gas fireplace, gas insert, or gas logs the best choice for your home? Will they be vented or unvented? Which brand will you choose?

To help you decide which gas fireplace will be the ideal choice for your home, we’re covering the difference between vented and unvented fireplaces in this blog.  


When you think of a traditional fireplace, you typically imagine a smoking chimney, which acts as an outlet for the smoke. Although gas fireplaces are fueled by either natural gas or propane, and therefore do not produce the thick, foggy smoke of burning real wood, they do generate harmful fumes. In a vented gas fireplace, two vents run up through the chimney — one to bring in fresh outdoor air and the other one to exhaust the fumes. Fireplaces using two vent liners are often referred to as “direct vent.”

Obviously, the biggest benefit of a vented gas fireplace is that it’s the safest option. With a direct vent to the outdoors, this gas fireplace ensures that carbon monoxide never lingers in your home. However, the downside is that they are more expensive to install because of the firebox construction and the two required liner vents. Although direct vent fireplaces are not quite as efficient as ventless models, their ratings are still very high. Not to mention, they are cleaner and safer. 

Vent-Free (Unvented)

A vent-free fireplace, on the other hand, does not require any venting. It pulls oxygen from the room to feed the fire. The fireplace has a regulator that produces a fine mixture of gas and air in a way that allows the gas to burn cleanly, and distributes the burnt fumes back into the room. 

Is that safe? Yes and no. Although there is much controversy surrounding the safety of unvented fireplaces, each product has to be tested to meet the federal health and safety requirements before it can be sold to the customer. Most, if not all, vent-free gas fireplaces come with additional safety features, such as oxygen detector sensors (ODS). This sensor measures the oxygen levels in the room and immediately shuts off the fireplace if the oxygen levels drop too low. It is also recommended that homeowners install additional carbon monoxide detectors throughout the home. 

Since vent-free fireplaces don’t release any air outdoors, they have an incredibly high efficiency rate of 99 percent. For some homeowners, the benefits outweigh the risks. 

Gas Fireplace Safety Tips

Whether you choose a vented or unvented gas fireplace, here are some safety tips to keep in mind.

Would you like to learn more about gas fireplaces from Utah’s leading fireplace experts? Contact the Croft Fireplace team today! We’re happy to help any residents of Salt Lake County, Davis County, Summit County, and the surrounding areas!