Vent-Free Alliance Hails Outstanding Health and Safety Record of Vent-Free Gas Products PDF Print E-mail

Rumors and Misinformation Answered with Fact-Based Documentation and Independent Research

Arlington VA. – January 22, 2008 - Vent-free gas heating appliances have an exemplary safety record spanning 27 years and installations in 18 million American homes.  Nevertheless,  rumors and misinformation have persisted over the health effects of vent-free products.

Consumers in the millions of American homes that use vent-free gas heaters, fireplaces, log sets, fireplace inserts, and stoves know that these appliances provide safe, reliable, and extremely efficient supplementary heating. But some prospective buyers are influenced by misconceptions and, in some cases, misinformation distributed by blogs and websites. 

In response to the rumors and misinformation, the Vent-Free Gas Products Alliance has compiled extensive documentation verifying that vent-free gas heating appliances meet authoritative indoor air quality guidelines.  The Alliance, a coalition of members of the Vent-Free Gas Products Section of the Air-Conditioning, Heating, and Refrigeration Institute (AHRI), has now mounted an intensive effort to communicate and share with HVAC professionals and homeowners the documented facts and results of independent research concerning indoor air quality from vent-free gas heating appliances.

 “Vent-free gas appliances are the perfect answer for supplementary home heating,” said Sue Walker, Chairman of the Alliance.  “Used in million of U.S. homes, these products boast an outstanding 27-year safety record.  Moreover, independent research studies have proven that vent-free products do not cause problems with indoor relative humidity or indoor air quality.  Thus, it should be no surprise that every U.S. code group and 49 states now allow the sale and installation of vent-free appliances.  The Alliance is proud to report that, having considered the excellent performance and safety record of these products, the Home Safety Council recently accepted the Vent-Free Gas Products Alliance as an official sponsor of the HSC’s Expert Network.”

Every vent-free gas product sold in the U.S. is equipped with a precision-engineered Oxygen Detection Safety-Pilot (ODS). The ODS acts similarly to a circuit breaker, automatically shutting off the vent-free gas appliance if the oxygen level in the room begins to fall. The minimum oxygen level at which the ODS must act is set by American National Standard (ANSI) Z21.11.2, which specifies numerous stringent design and performance safety requirements that an appliance must meet in order to be certified as compliant by an independent third party.

This standard has been very effective.  The staff of the U.S. Consumer Product Safety Commission (CPSC) has stated that it is not aware of any documented incident in the CPSC In-Depth Investigation (IDI) database of fatal CO poisoning associated with an ODS-equipped vent-free gas heating product.
In addition, vent-free gas appliances are equipped with an integral, non-adjustable pressure regulator that prevents over-firing in the event of increased gas pressure. Safety grills must be installed on vent-free heaters, and fire screens and hoods are standard for vent-free gas logs and fireplaces. Installation of a vent-free gas product must be done by a licensed installer, in accordance with local code requirements and the product must be permanently installed and properly sized for location, with appropriate clearance from combustibles.
Because of these many safety features, there is no need to open a window to ventilate a vent-free gas heating appliance.  In 1999, ANSI removed language recommending an open window for ventilation. Although some articles written today include a statement about opening a window when burning a vent-free gas appliance, this is a misconception. Opening a window is only recommended for kerosene room heaters and not for permanently installed unvented supplemental gas appliances. 

After reviewing the health and safety record of vent-free gas appliances, the Home Safety Council (HSC) has accepted the Vent-Free Gas Products Alliance as an official sponsor of the HSC’s Expert Network. As the only national nonprofit organization solely dedicated to preventing home related injuries, the HSC provides several national programs to educate people of all ages in how to be safer in and around their homes. The HSC’s Expert Network is a free online resource for fire and life safety professionals across the country.

Independent Studies of Vent-Free Products:  Indoor Air Quality and Indoor Humidity

To address questions concerning the impact of emissions from vent-free gas appliances on indoor air quality, an independent research study was conducted by the American Gas Association Research Division (AGAR) in 1996. This study, titled The Effect of Properly Sized and Operated Vent-Free Gas Products on Indoor Air Quality (IAQ), concluded that vent-free gas appliances provide clean heat that meets all nationally recognized guidelines for acceptable indoor air quality.

Regarding indoor humidity, all homes need some form of moisture indoors for health reasons and ease of breathing in the high heating months. Vent-free gas products produce small amounts of moisture in the air, which aids in achieving a comfortable moisture level in the home. According to a research study completed in December 2002 by risksciences, LLC, an independent scientific consulting firm nationally recognized for its expertise in human exposure modeling in residential environments, vent-free gas products contribute less moisture to the home environment than would be required to cause mold and mildew growth.

Vent Free Appliances: Economical to Install, Extremely Energy Efficient, and Aesthetically Pleasing

With a vent-free gas appliance, all that is needed is a gas line for economical installation and 99.9 percent energy efficient heat. In a vent-free fireplace, no heat is lost up the chimney because the damper is closed, or with a vent-free gas fireplace insert, there is no chimney, flue, or vent. Vent-free products range from 5,000 to 40,000 Btu – including 8,000 to 10,000 Btu units for bedrooms and 2,000 to 6,000 Btu units for bathrooms. For vent-free fireplaces and log sets, homeowners can choose from such wood styles as driftwood, oak, weathered oak, maple, pine, aspen, birch, and many others. With no wood to haul or ashes to clean out, homeowners appreciate the convenience, savings of time and effort, and ease of use of vent-free gas products. Vent-free logs are ideal for a quick installation in an existing fireplace. Homeowners can also look for a cross certified vented and vent-free gas log set to give them the best use for both appliances.
For a free copy of the new Consumer Guide to Vent-Free Gas Products – which includes detailed sizing guidelines, and the results of the independent studies on indoor air quality and indoor relative humidity – and other new publications on energy- and cost-savings, write to the Vent-Free Gas Products Alliance, 2107 Wilson Blvd., Suite 600, Arlington, VA 22201, email to, or visit  This Web site offers complete coverage of all publications, press releases, power point presentations, members of the Alliance, technical/codes and standards information, exhibits and results of all indoor air quality scientific research.