Many homeowners choosing gas fireplaces
For centuries, homeowners have gathered around a fire to keep warm, chat and cook their meals. Today, most American homes have central heating, but the allure of a fire hasn’t diminished — whether it’s a wood-burning fireplace, a free-standing gas stove or, in a pinch, even the image of a burning log on a midnight television screen!
While there’s something to be said for the sounds and smell of a wood-burning fireplace, a lot of homeowners are opting for the ease of a gas insert. Today’s gas fireplaces look realistic, need minimal maintenance and can heat an entire room.
There are three kinds of gas fireplaces.
Gas inserts: This is gas fireplace that can be fitted into an existing wood burning fireplace.
Built-ins: A fireplace that can be installed into the wall where there wasn’t one previously
Log sets: Gas burners that sit in existing fireplaces and are more for aesthetics than heat
Gas Fireplace Cost: $2,000 to $5,000 for the fireplace and installation. This is not a DIY project and should be handled by someone who can verify that the fireplace is vented properly.
Ventilation:
Although a gas fireplace doesn’t emit the smoke or leave ashes like a traditional wood-burning fireplace, they do emit carbon monoxide and other chemicals. Many gas fireplaces and inserts are vented versions that recycle air 
and exhaust directly through an exterior opening.
However, a vent-free gas fireplace can be installed anywhere because they don’t require access to an exterior wall opening. They are required to be cleaner burning and have an oxygen-depletion sensor that will shut off the fireplace if the level of oxygen is too low in the room. Vent-free gas fireplaces are not allowed in California, New York City and a few other places.
Pros of Going Gas:
A gas fireplace can be built nearly anywhere in your home and provides a clean, low-maintenance look of a fireplace. You can control the temperature of the fire with a built-in thermostat and can start the fire with a switch or button. Unlike wood-burning fires, gas fireplaces are efficient and return as much as “75 to 99 percent of a fuel’s energy back as heat,” according to “This Old House.” Some gas fireplaces have built-in fans which can heat an entire room quickly.
Cons of Going Gas:
For most people, the cost of installation and the gas or propane to run it is a big enough turn-off due to cost. Additionally, there are some environmental concerns with gas fireplaces, specifically vent-free versions due to carbon monoxide output.