Bottom Line: Vent-Free Gas Appliances – Know the Facts

By Mary S. Carson
February 2007

Did you know:

• Vent-free supplemental natural gas or propane fueled heaters are allowed in bedrooms and bathrooms in most areas of the U.S.
• Vent-free units have no restrictions relative to sleeping in a room with a vent-free appliance
• Vent-free units do not require an open window
• There are no CO incidents reported by the CPSC from an ODS-equipped vent-free appliance
• Vent-free natural gas or propane fueled appliances are allowed in 49 states
• Vent-free units are now allowed in every major code in the U.S.

Since 1980, more than seventeen and one-half million American homes in 49 states have relied on vent-free gas space heaters, fireplaces, logs, inserts, and stoves for supplemental home heating. Vent-free products range from 5,000 to 40,000 Btu – including 8,000 to 10,000 Btu units for bedrooms and 6,000 Btu units for bathrooms. In most areas of the U.S. vent-free supplemental heaters are allowed in bedrooms as well as bathrooms, as long as they are wall hung, permanently installed and do not exceed the required Btu limit. These are the only restrictions relative to the use of vent-free gas appliances in bedrooms; otherwise, there are no restrictions relative to sleeping in the presence of a vent-free gas product.

In the past year, vent-free gas heaters have been unfairly maligned by a number of syndicated columns picked up by newspapers all over the country. These articles have falsely placed vent-free gas appliances in the same category as kerosene room heaters and they have advised consumers to ventilate these units to the outside and to never sleep in a room with an unvented room heater. With respect to the natural gas and propane fueled vent-free gas appliances, this advice has no basis in fact. A review of the U.S. Consumer Product Safety Commission (CPSC) database that has been tracking these products for 25 years confirms that there has never been a documented poisoning or fatality resulting from CO emissions associated with a vent-free supplemental heating gas product.

As of January 2006, vent-free supplemental gas heating appliances are allowed in all major national building codes in the U.S. in forty-nine states. (California is the only state that does not yet allow the use of unvented appliances). The last major code body to accept their use was the International Association of Plumbing and Mechanical Officials.

It is also important to know that it is not necessary to open a window when using a vent-free gas appliance. The national product standard ANSI Z21.11.2, removed this language eight years ago, based on research showing it to be unnecessary. All natural gas or propane fueled unvented products are equipped with an Oxygen Detection Safety Pilot (ODS). Consumers need to make sure that they follow the recommended ventilation guidelines supplied by the manufacturer.

For more detailed information go to www.ventfree.org to review technical research and information on how the ODS operates. This site is provided by the members of the Vent-Free Gas Products Alliance, which is a coalition of members of GAMA – a national trade association representing more than 200 manufacturers of space heating and water heating appliances and equipment all certified to national ANSI standards.

Mary S. Carson is Program Director of the Vent-Free Gas Products Alliance