Gas Logs: Vented vs. Ventless

Many homes I inspect have wood-burning fireplaces that have been converted to gas. The choice of many homeowners to convert to gas logs isn’t surprising when you consider how much easier gas fireplaces are to maintain than traditional wood. Of course, nothing beats the authentic look, sound and smell of a real wooden fire, but if you have chosen (or are trying to decide) to convert to gas, there are some key things you should know.

Gas logs come in two varieties: vented and ventless. As their name suggests, vented gas logs are vented, just like real wood fires. This provides a major benefit as well as a major downside. The benefit is that vented gas logs resemble a real wood fire in appearance. The flames dance around the logs in a varied and widespread pattern, similar to what you would see in a traditional wood-burning fireplace, providing a cozy and inviting ambiance. Because they are vented, though, they do not provide much heat as most of the heat goes straight out the chimney. Vented logs require that the fireplace damper be permanently left open, which provides other downsides.

Ventless gas logs are the exact opposite. They do a great job of providing heat, but they do not resemble the look and feel of a real wood fire. Typically, two or three small flames are present and come up through spaces between the logs, touching the logs very little, if at all. You can easily tell that gas logs are ventless by their inauthentic look. Another downside to ventless logs is that they use oxygen from within the home and add moisture to the air. For this reason, they should not be run for long periods and, ideally, only about an hour at a time. It is also advisable to open a window to allow fresh air into the home, which defeats the purpose somewhat of the heating benefit ventless logs provide. The fact that ventless fireplaces deplete oxygen and add moisture has led some municipalities to ban them altogether, and manufacturers have developed sensors for these systems that are designed to shut off the fire if oxygen levels are too low. Of course, these sensors are only effective if they are working properly. In any case, ventless gas logs should only be used for occasional supplemental heating and never as a primary heat source.

If you decide to convert to gas logs, consider what you want most. If you prefer the look and ambiance of a real wood fire above heat, go with vented logs. If your main concern is heat and you aren’t as concerned about the look of your logs and fire, you may wish to go with ventless logs. If you choose ventless, be sure that they are permitted in your area before making the investment, and be diligent in taking safety precautions when running the fireplace.

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Author: hillinspections

I am a Certified Master Inspector (CMI) and the owner and operator of Hill Property Inspections LLC, the top-rated inspection company in the greater Johnstown, PA area, based out of western Pennsylvania. I specialize in property inspections and environmental testing services and have a passion for helping my own clients and other families in learning to properly maintain their homes. I’m also the owner of Hill Pest Control, LLC and a pest management professional committed to helping our clients rid their homes and businesses of unwanted pests. I am an Army veteran, former State Farm Insurance Agent, and real estate investor with experience in all facets of real estate construction, transaction and insurance. I am also the founder and President of the Southwestern PA Chapter of the International Association of Certified Home Inspectors (InterNACHI) and an affiliate member of the Cambria-Somerset Association of Realtors (CSAR).

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