Get Facts About Vented Gas Fireplaces

How much do they cost, and how effective are they?



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Gas fireplaces might be an ideal choice for anyone who wants to enjoy the warmth of a fire without the chores of hauling wood and cleaning ashes. Gas fireplaces grow in popularity every year, and manufacturers offer a wide selection of appliances, including gas logs and contained fireplace units that are mounted to a wall.

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

Using a Traditional Hearth

Vented gas logs can take the place of wood in a traditional hearth and chimney. You can choose a unit that burns either natural or propane gas, but both types are always burned with the damper open. Keep these important safety tips in mind:

  • Gas fireplaces are not a solution to a problem chimney. If the chimney is damaged, dirty, or doesn't draw air well enough to burn wood, it is not suitable for gas logs.
  • Chimneys previously used to burn wood should be professionally cleaned to remove creosote before gas logs are used.
  • Building codes may require the damper in your chimney to 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 produced as a byproduct when fuels such as natural or propane gas, kerosene, and wood are burned. Follow the manufacturer's instructions exactly when using any type of fuel-burning appliance.

Other Venting Options

If you do not have a chimney for top-venting, a special pipe can be installed to vent the appliance.

If a top-vent isn't practical, consider direct venting, which uses a two-layer pipe running 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. The inner pipe takes waste to the outside.

Direct venting is considered a safe system, since 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.


How much you need to spend on converting a traditional hearth or installing a new gas log fireplace depends on multiple factors and can range from less than $1,000 to more than $5,000, according to

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 is 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.

If you aren't converting a traditional fireplace, 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 is not available.

Natural gas often is more convenient because it is piped directly into your home, and no tank needs 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 are in—even large living rooms or family rooms. Most will have adjustable settings, so a 40,000-BTU fireplace does not need to be operating at full capacity all the time. While actual rates depend on how much you pay for gas where you live, estimates that most fireplaces should cost less than $1 per hour to run. Gas also has advantages over wood, according to, primarily in the ability to more precisely control temperature almost instantaneously.

Burning wood, on the other hand, takes time to light and get to a temperature that can be maintained. Even then, the fire needs constant attention that is not necessary with a gas fireplace.


The care required for a gas log fireplace is significantly less than that of a traditional wood-burning fireplace. Most of the work that needs to be done is simply making sure all systems, such as ventilation, pilot lights, ignition switches, etc., are operating properly. The fireplace also will 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 per year and perform routine maintenance.

This should cost about $150.