Why Does Mark Harris Homes Not Use Ventless Gas Logs In Homes They Build?

Updated: Aug 15, 2019

Types of Gas Logs

There are two types of gas logs that can be used in gas fireplaces: vented and ventless (or vent-free). Ventless gas logs are built so that they burn gas cleanly. Similar to the gas stove in your kitchen, ventless gas logs produce almost no exhaust, and thus, you can burn them with the damper closed.There are several benefits to using ventless gas logs. The first is that almost all the heat the logs produce enters the room, so they are substantially better at warming rooms than vented logs. Also, they are better for the environment and more sustainable, because they create less pollution and use less gas.However, despite the benefits that accompany ventless logs, our company chooses not to use them in the homes we build. This is because the logs have a number of drawbacks that make them dangerous and challenging, including the issues below.

Associated Health Risks

There are several serious risks associated with using ventless gas logs, especially when they’re used improperly. First, you cannot burn ventless logs inside with the windows closed for very long or they deplete your home’s oxygen (and once you open the windows, much of their heat escapes). Ventless logs are required to have an oxygen depletion system built into them (as well as a CO2 detector), but if these systems malfunction, you won’t be alerted about some potentially serious health risks. Next, ventless gas logs are known to cause eye irritation and coughing spells, especially to those who are sensitive. Finally, ventless gas logs pose enough of a risk that most companies recommend not using them when pregnant women or small children are in the room.

Bad Odor

Ventless gas logs create a smell reminiscent of kerosene when burned.

Potential Mold or Mildew

When ventless gas logs burn, they create carbon dioxide and water vapor. While these byproducts are clean, they can cause excess moisture in your home, resulting in unwanted mold or mildew.

Required Professional Care and Logistical Difficulties

Ventless logs are not a DIY job. Instead, they must be installed by a professional who can test to make sure your gas pressure is sufficient and that your building meets the codes and specifications required. Ventless logs are illegal in the state of California as well as other cities in the United States. Where they are legal, they require different combustible clearances than wood burning stoves, and they may also require a hood to divert heat away from a mantle. Also, they often cannot be installed in bedrooms or confined spaces. Finally, ventless gas logs should be cleaned and reset by a professional each year.

Aesthetic Drawbacks

In a fireplace with ventless logs, the flame is low in height and blue (not yellow) and it does not dance around like a real fire — in fact, the fire does not actually touch the logs in the fireplace.


At Mark Harris Homes, we highly recommend that you purchase a home that uses vented gas logs. Not only will you be able to relax by the side of a more beautiful, traditional fireplace, you can avoid any health risks or discomfort and simply enjoy the warmth it produces.

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