Full Description

Unvented gas heating and hearth appliances are marketed in most of the US as energy-efficient. Previous modeling studies have shown that unvented products that are installed, sized, and operated according to manufacturers’ instructions conform to reasonable IAQ standards and guidelines for CO, NO₂, CO₂, O₂ depletion, and H₂O vapor. Measured concentrations in some homes, as well as anecdotal evidence, have raised concern that unvented fireplaces may be a significant source of indoor air pollution.