Indoor combustion product concentrations resulting from the use of unvented gas fireplaces

Paul W. Francisco, Jeffrey R. Gordon, William B. Rose

Research output: Contribution to journalConference articlepeer-review


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, NO 2, 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. In 2005, a study was undertaken to measure concentrations of combustion products in 30 homes over two winters in homes where unvented gas hearth appliances were used. The primary goal of the study was to measure the indoor air concentrations of combustion gases and to compare these results with IAQ standards and guidelines, and to obtain these results for units with common usage and maintenance patterns, rather than new units with assumed usage patterns. In the first winter of study (2005-2006), measurements were taken in 15 homes. A cart was prepared that contained chemiluminescence equipment for measurement of NO2 and O2 (depletion) concentrations, non-dispersive infrared (NDIR) equipment for measurement of CO and CO 2 concentrations, and polymer thin-film capacitance for measurement of water vapor. Additional equipment provided H2O and CO measurements at six different locations. The equipment was calibrated with known gas concentrations for each placement, and was in operation for 3-4 days at each of the 15 homes. This paper presents the findings from the 15 homes tested in the first winter. It describes the equipment setup and shows the resulting concentrations with respect to standard and guideline thresholds for combustion gas concentrations.

Original languageEnglish (US)
JournalIAQ Conference
StatePublished - 2008
EventHealthy and Sustainable Buildings Conference, IAQ 2007 - Baltimore, MD, United States
Duration: Oct 15 2007Oct 17 2007

ASJC Scopus subject areas

  • Building and Construction
  • Environmental Engineering
  • Public Health, Environmental and Occupational Health


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