Mind Your Mantel­

For gas and wood inserts, be sure to follow the unit’s mantel clearance guidelines unless you have a noncombustible mantle. Even if the mantel can’t go up in flames, the paint used on it can discolor if it isn’t heat-resistant.­

Gas Fireplace Inserts

Homeowners who have access to natural gas can put a gas insert in their fireplace.

These inserts must be professionally installed. A gas line needs to be run to the fireplace. If you already use gas in the house, this could take a few hours, depending on how far away your gas source is. Two small, flexible tubes run down through the chimney; one brings fresh air into the insert for combustion, and the other is for exhaust [source: Kaufman].

Gas fireplace inserts are extremely efficient, typically kicking out between 25,000 to 40,000 BTUs, which is enough to comfortably heat a medium-size room. Their energy efficiency ratings run from 76 percent to 83 percent. Prices range from $1,400 to $3,000 for a top-of-the-line gas insert. Because they're great for zone heating, they can help homeowners keep their gas bills down.

Once the gas insert is installed, it won't need much maintenance aside from cleaning the glass door. There's no need to refuel, and the chimney doesn't need cleaning because gas burns so cleanly. However, because gas burns so cleanly, it can be difficult to determine if there's a leak. That's why a carbon monoxide detector is so important -- it can let you know there's a problem before it's too late. These run about $20 at any home improvement store [source: Kaufman].

"Logs" for gas inserts are made of ceramic or ceramic fiber; they're placed over a burner to give the look of a traditional flame. Vented log usually come with most units. Vent-free log sets are offered on inserts that use an oxygen depletion sensor, which further boosts efficiency. This technology isn't approved for use in all states and can't be used in bedrooms because it requires a closed damper.

Although gas fireplace inserts don't need electrical power, models with a fan or a blower will need to be plugged in to work. Some models come with remote controls and can even run on wall thermostats.

Like your flames the old-fashioned way? Read on to hear about wood fireplace inserts.