Vented Gas Logs
Easy and inexpensive fireplace retrofit
If you already own a traditional wood burning fireplace and want to enjoy the convenience of gas with the conventional beauty of burning logs, then vented gas logs are a great option for you. Basically, the logs are put into your existing fireplace where actual wood would normally go. Your existing chimney is used for exhaust ventilation, so the damper is always kept open when burning a natural gas fireplace of this kind. If your chimney has previously been used for wood-burning activities of any kind, then there is some creosote buildup – the chimney must be professionally cleaned before using it for burning natural gas, or else a chimney fire could result. Never take chances with the safety of your family and home.
It's important to note that use of vented gas logs are absolutely not a solution for a problem chimney. If your chimney is damaged, undersized, or otherwise insufficient for burning wood, then it is also insufficient for burning natural gas. Fortunately, there are other options for the exhaust ventilation of a gas fireplace – the use of a chimney is normally referred to as a simple top-vent, but there are also options of a top-vent pipe or a direct vent. The top-vent pipe uses a dual-layered pipe (often steel) to directly vent the combustion gases out of the house. This option is used most often in homes which do not have any kind of existing chimney – it is essentially the installation of a mini-chimney. The other choice is a direct vent, which uses two pipes that simply go through a nearby wall – one is for intake air for combustion while the other is for the exhaust air from the combustion.
Vented gas logs tend to be more visually appealing than ventless gas logs or some direct vent fireplace inserts. Many of these can even burn with a yellow flame like the flame one would expect from a "traditional" wood-burning fireplace – however, this flame is inefficient and represents a lower level of combustion, which can still cause creosote deposits in the chimney. Most ventless gas logs and other natural gas fireplaces burn with a blue flame, which is more efficient and offers better combustion, without deposits on your chimney.
So, although vented gas logs are less efficient, they tend to be more aesthetically pleasing and offer you the ability to continue using your existing fireplace - not a bad tradeoff overall.