Get Facts About Vented Gas Fireplaces

How much do vented gas fireplaces cost, and how effective are they?

A divan with a fuzzy blanket and a book in front of a burning fireplace
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Gas fireplaces might be an ideal choice for someone who wants to enjoy the warmth of a fire without hauling wood and cleaning up ashes. Gas fireplaces grow in popularity every year, and manufacturers offer a wide selection, including gas logs and contained fireplace units that are mounted to a wall.

Some gas log fixtures are vented so that any dangerous gases produced during the burn will travel outside, just as they move up and out of a chimney in a traditional wood-burning fireplace. But there's more than one way to vent an appliance, so you can probably install vented gas logs in your home even if you don't have a usable chimney.

Using a Traditional Hearth

Vented gas logs can take the place of wood in a traditional hearth and chimney if you choose a unit that burns either natural or propane gas. Both types are always burned with the damper open, but you'll want to keep some important safety tips in mind.

Gas fireplaces aren't a solution for a problem chimney. A chimney isn't suitable for gas logs if it's damaged, dirty, or doesn't draw air well enough to burn wood.

Chimneys that were previously used to burn wood should be professionally cleaned to remove creosote before any gas logs are used.

Building codes might require that the damper in your chimney be permanently blocked open if you install gas logs. You can reduce drafts and heat loss by installing glass doors in front of the gas fireplace, but the doors must remain open while the fire is burning.

Carbon monoxide (CO) is a colorless, odorless, potentially lethal gas that's produced as a byproduct when fuels such as natural or propane gas, kerosene, and wood are burned. Be sure to follow the manufacturer's instructions exactly when using any type of fuel-burning appliance.

Other Venting Options

A special pipe can be installed to vent the appliance if you don't have a chimney for top-venting.

Consider direct venting, which uses a two-layer pipe, if a top-vent isn't practical. Run the pipe through a hole in the wall behind the unit, or positioned slightly above it. The outer pipe draws air in from the outside to create combustion for burning the gas, while the inner pipe takes waste to the outside.

Direct venting is considered a safe system because no air from inside is used in combustion, and all wastes flow to the outside. Both actions reduce the risks of carbon monoxide buildup within the house.

Costs to Convert or Install

The cost of converting a traditional hearth or installing a new gas log fireplace will depend on multiple factors. It can range from less than $1,000 to more than $5,000, according to costhelper.com.

Gas logs for a conversion project range from about $300 to $550, and installation generally costs between $200 and $350.

A more expensive option is a steel or cast-iron insert that's placed inside a traditional hearth and chimney. The insert contains its own gas log and pipe system for ventilation. These cost anywhere from about $1,200 to $2,900, with installation adding another $600 to $1,000.

A new direct vent unit can cost anywhere from about $1,200 to $3,200, depending on available features such as timers or remote controls. Installation can be done for as little as $600, but complicated setups can run as much as $5,000.

Natural Gas vs. Propane

Gas log fireplaces can be set up using the same natural gas that might be piped into your home to fuel other gas appliances, or they can be set up to use propane.

Natural gas is more common in urban or suburban settings, while propane might be the only option in more rural settings where municipal gas service isn't available.

Natural gas often is more convenient because it's piped directly into your home, and no tank has to be filled. Natural gas also tends to be cheaper than propane.

Heat Output

Gas log fireplaces generally are capable of heating the rooms they're located in—even large living rooms or family rooms. Most will have adjustable settings, so a 40,000-BTU fireplace doesn't have to be operating at full capacity all the time.

Actual rates depend on how much you pay for gas where you live, but bobvila.com estimates that most fireplaces should cost less than $1 per hour to run.

Gas also has advantages over wood, primarily in the ability to more precisely control temperature almost instantaneously. Burning wood, on the other hand, takes time to light and to get to a temperature that can be maintained. Even then, the fire needs constant attention. This isn't necessary with a gas fireplace.

Maintenance

The care required for a gas log fireplace is significantly less than that of a traditional wood-burning fireplace. Most of the work involves simply making sure all systems, such as ventilation, pilot lights, and ignition switches, are operating properly.

This type of fireplace will also generate soot that should be cleaned up, but this is far less than what a wood-burning setup produces.

This Old House recommends having a certified technician check the fireplace once a year and perform routine maintenance. This should cost about $150.