Vent Free / Ventless Gas Logs

At Chimney Mischief we have been selling and installing vent free gas logs (also known ventless gas logs or unvented gas logs) since they were widely introduced in the 1990’s. They bear very little resemblance to their vented counterparts in the way they operate or in how they can be made to look more aesthetically pleasing. The main difference is the burner, and with vent free logs it must be designed to burn the natural gas or propane almost perfectly, like a gas stove in the kitchen with burners that have a blue flame which is an indication of the close to perfect burn. Unvented gas logs are really nothing more than a gas heater (space heater) built in such a way as to allow the placement of concrete or ceramic fiber logs to wrap around it, and thereby to look appropriate in a fireplace. They don’t need a fireplace to operate properly like vented logs, again referring to the space heater concept as a space heater could almost go anywhere in a home.

Unvented gas log sets must be set up exactly as specified in the instructions, no exceptions ever. Failure to do so could lead to some level of contamination of the indoor living space, depending on the total volume of indoor air available and the types of products in that area. Burning one cubic foot of natural gas requires 10 cubic feet of air (oxygen and nitrogen) and produces 2 cubic feet of water vapor, one cubic foot of carbon dioxide (both greenhouse gases) as well as the flame you see and the heat you feel. Each living space consisting of paint, carpet, furniture, stored products for home maintenance, etc. is unique and will react differently. Through a process called outgassing different chemicals in the form of gases can be released from the products in the living space. The requirement is that enough air (makeup air) be available to reduce or eliminate the outgassing or dilute it to acceptable levels. What is acceptable is the center point of the entire issue of the safety or usability of unvented gas logs, for example at present they cannot be installed in homes in New York or California. Some people, especially smokers will almost never have a problem with unvented logs, while those with respiratory conditions or sensitivities have a higher level of incompatibility. There is the largest group of people where the outcome is unknown and for this reason we at Chimney Mischief like to view the space where they will be installed and talk to the homeowner and this usually leads to a prudent discussion about the plausibility of having an unvented log set. This process has allowed for mostly but not all successful installations. There is a 2 week trial period where the product can be returned for credit but the labor for installing the log set will not be refunded.

Rhpeterson company makes a very wide range of unvented log sets, some with the much desired glowing ember bed of a vented log set, and though nowhere near as large as its vented cousin it makes quite a difference. Their logs for these sets are also quite attractive in comparison with what you would see at the big box retailers, and like vented logs can be set up with several types of remote controls. Our favorite over the years has been the G10 Charred Aged Split Unvented log set available in 3 sizes: 16/18”, 24”, and 30”. As with all unvented log sets they have Oxygen Depletion Sensors that will shut off the burner if it detects an undesirable condition, or if it is not cleaned regularly so as to stop its detecting ability. Because of this sensor and other necessary controls unvented burners and logs are more costly then vented burners and logs, though this cost may be made up in other areas of the cost of the total fireplace system.

Our basic rule of thumb is what I call the 80/20 rule.

Vented gas logs are 80% for aesthetics and ambience and 20% for heat.

Unvented gas logs are 80% for heat and 20% for aesthetics and ambience.

There are products that will somewhat adjust this ratio if desired.

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Chimney Mischief
2064 Briarcliff Rd.
Suite 109
Atlanta Ga 30329
(404) 377-1254 ‎

Atlanta’s Chimney Company:

We are the chimney company in Atlanta, GA that you can rely on for honesty and reliability. Our Atlanta chimney sweeps have many years of experience in the chimney and fireplace industry. Call us today and get a consultation about your chimney maintenance or custom chimney construction needs. We also service Sandy Springs, Dunwoody, Marietta, and the surrounding areas.