New Study Investigates Impact of Vent-Free Gas Heating Appliances in “Tight” Homes
April 9, 2013
Francis Dietz, Vice President, Public Affairs
Direct: 703.600.0355

Arlington, VA — A new study on nitrogen dioxide (NO2) emissions from vent-free gas fireplaces, logs, inserts, space heaters, and stoves found that the use of those appliances in “tight” homes does not result in NO2 concentrations that exceed guidelines for indoor air quality. “Tight” homes are those that are designed to be as air-tight as possible, usually with mechanically controlled ventilation. Today, many new homes are designed in this manner. The study was commissioned by the Vent-Free Gas Products Alliance Product Section of the Air-Conditioning, Heating, and Refrigeration Institute (AHRI), and included 100,000 simulations.

“There has been some concern recently about NO2 levels in homes that are sealed more efficiently than they have been in the past,” said Sue Walker, chair of the Vent-Free Gas Products Alliance Product Section and Senior Director of Government Affairs at Empire Comfort Systems. “As manufacturers of this energy-efficient home heating option, it was incumbent upon us to investigate this matter and ensure the safety of these products.”

Third-party toxicology firm toXcel conducted the study, which compares predicted NO2 levels from vent-free appliances against NO2 limits specified by the U.S. Consumer Product Safety Commission, Health Canada, and the World Health Organization.

The details of the study are available here. For more information about vent-free gas products, visit the Vent-Free Gas Products Alliance’s website at