There are two types of gas logs available; the traditional vented type and the newer vent-free type.
The vented type must have a working flue (chimney) if they are to be installed.
The vent-free or un-vented type does not need a flue.
Vented Type Fireplaces
For regular vented gas logs the flue must be in reasonable condition to take the carbon monoxide out of the structure. Many older homes have poor chimneys/ flues and homeowners install these gas logs thinking that the chimney will not really be used because it is only gas. Unfortunately the exhausted gas creates a lot of condensation that in turn causes a break down or deterioration of the older brick lined chimneys.
When vented gas logs are installed the damper must be modified in such a manner that it is prevented from being closed fully at any time. Vented gas logs should only be used in conjunction with a chimney that is stainless steel lined or has clay liners that have not been compromised.
Direct Vent Fireplaces
Generally built into a pre-fabricated fireplace unit that vents to the outside using a short flue that goes horizontally through the wall of the house from the fire place. (These are very common in new construction)
Vent Free Fireplaces
Vent-free gas logs are often used where there is no chimney or flue pipe available, or where the flue pipe has deteriorated and there is a concern about its safety. While vent-free gas logs are approved for use in many states, there is no national consensus regarding the safety of their emissions indoors. These flue-less fireplaces exhaust pollutants such as carbon monoxide, carbon monoxide, nitrous oxides, and an enormous volume of water vapor directly into the living space.
NOTE: Vent Free Logs cannot be installed in any bedroom.
We do not recommend the installation of vent free logs due to possible health concerns from Carbon Monoxide poisoning.
The Gas Appliance Manufacturers Association recommends that gas logs should not be used for more than 4 hours per day.
Vent-free gas logs produce a tremendous amount of heat and can often damage or burn a fireplace surround that was designed for use with a wood burning fireplace.
Instillation should only be carried out by a professional, in many areas a building permit will be necessary. A gas shut off must be installed in the same room within 6 feet of the log unit.
Recommend: Installing a carbon monoxide detector.
NOTE: All references to gas, includes propane.