About Unvented Logs

About Unvented Gas Logs

Vent Free System
	What is an Unvented or Vent Free Hearth Product? Unvented, or more correctly, "room vented" products are designed to operate with all the gases and other by-products of the burning process coming into the room. they use an ODS or Oxygen Depletion Sensor which may act as a safety shutoff should the unit not operate properly. In addition, several manufacturers of unvented hearth products also include a carbon monoxide detector as a part of the system.
Unvented Schematic
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Is Vent-Free Gas Heating Right For Me? While most states permit installation of vent-free gas heating appliances, a few states still prohibit residential use. Very often, that is because a state's building codes have not caught up with vent-free technology. Currently seven states prohibit residential use: ALASKA, MASSACHUSETTS, MONTANA, MINNESOTA, COLORADO, UTAH, CALIFORNIA. However, many local and state codes are currently revised to reflect acceptance of this new technology. *Several counties and municipalities in Colorado and Utah permit the vent-free product. Wisconsin restricts installation in homes built after 1980. Because states, counties and municipalities adopt various codes, please check with your installer or local code officials to assure the current code in the city where you plan to install permits vent-free gas heaters. NATIONAL BUILDING/MODEL CODES The following six model building codes permit the installation of listed vent-free products. • National Fire Protection Association (NFPA) • Building Officials and Code Administrators (BOCA) • Southern Building Code Congress International (SBCCI) • Council of American Building Officials (CABO) • International Mechanical Code (IMC) • International Fuel Gas Code Only the International Conference of Building Officials- Uniform Mechanical Code (ICBO-UMC) does not permit vent free products.
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Are Unvented Models Safe?
Yes when properly sized, installed and operated, they are listed to be safe by ANSI standard Z21.11.2. However, many building scientists and indoor air quality experts have voiced concerns that proper sizing and operation of vent less models is not occurring in all circumstances.
Although Vent-Free appliances are rated at 99+ efficiency, low levels of carbon monoxide, nitrogen dioxide and high levels of moisture can cause health problems. Some Recommendations: DO NOT Install if anyone in your house is pregnant, asthmatic, anemic, diabetic, intoxicated, smokes or has heart, circulatory or respiratory problems, or use around babies. DO NOT use the appliance for more than 4 hours at the time. DO NOT use as sole heat source. DO NOT use in very air-tight homes. DO NOT install in a bedroom or bathroom.
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What Could Happen If An Unvented Model is Not Properly Sized To The Room?
The biggest concern is excess moisture in the home. A principal by-product of burning gas is water vapor. An unvented appliance operating at 25,000 BTU/hr will put approximately one quart of water per hour into that room! In new homes which are tightly insulated to today's energy codes, this excess moisture can become "trapped" in the home, considering on cool surfaces such as window glass and frames. This in turn can lead to the development of mold and mildew which have a negative impact on the air you breathe inside your home.
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The Difference Between Direct Vent And Unvented Hearth Products.
For starters, you should check with your local building code to confirm if unvented products are allowed to be installed. For instance there are several states that ban their use entirely. Secondly, consider the "comfort control" you have with direct vent models. Many offer options that allow you to put excess heat into other rooms, or outside the home completely if you choose. ( A nice feature when you're entertaining a room full of guests). Since all the heat from an unvented type product comes into the room, it make a room uncomfortably hot in a hurry!