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Articles > Gas Appliance Venting Options

9 Oct 2006


Understanding GAS APPLIANCE Venting Terms
Gas appliances offer venting options that make it easy  to install a fireplace or stove nearly any where you can dream of. When considering installing a gas appliance, consider the venting options that are open to you in choosing the right appliance for the right job.
In historic homes it's preferable to upgrade the existing fireplace if possible, and this will add considerable resale value to your home. Upgrading existing fireplaces and old chimneys will require the talents of an experienced chimney professional; we can often help locate chimney craftsmen across the US.
Installing a new fireplace or stove is an easier task that may be done by other tradesmen. Always use the services of the most experienced and qualified technician you can find. Gas lines should only be run by licensed plumbers or HVAC technicians (check your local area requirements). When searching for a chimney sweep or fireplace installer, ask if they are members or are certified by the National Chimney Sweep Guild or the Hearth Products Association.
Your venting options will help narrow down some choices:
Direct vent fireplaces have more versatile installation options, including a horizontal vent. Using a double wall pipe, combustion air enters the fireplace through the outer chamber and exhausts through the inner chamber. Direct vent systems use a glass window because it is a sealed system

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B-vent (Natural Vent) stoves use room air for combustion and send exhausts up the chimney. B-vent chimneys must run inside the house and exit the roofline, or can be installed inside of an exterior chase if installed at an outside wall.


Although they're rated at 99+ efficiency, low levels of carbon monoxide, nitrogen dioxide and high levels of moisture can cause health problems in certain people. The moisture (nearly a gallon of water per gallon of gas) can cause problems in your home such as mold and mildew which can damage the structure and irritate allergies and asthma.
We recommend a vented unit whenever possible and that you follow these general guidelines:
-DON'T USE if anyone in the house is pregnant, asthmatic, anemic, diabetic, intoxicated, smokes or has heart, circulatory or respiratory problems or around babies.
-DON'T USE more than 4 hours at a time nor more than 40 hours per week.
-DON'T USE as a sole source of heat
-DON'T USE in very air-tight homes
-DON'T install in a bedroom or bathroom
CHECK LOCAL BUILDING CODES as further restrictions may apply. Vent-free appliances may not be installed in bedrooms or bathrooms, or in small rooms defined as a "confined space".