Incomplete Combustion 2 : Burning with an insufficient supply of air so that the burning substance is only partially consumed and could be burned further with an additional air supply
NFPA 97 Standard Glossary of Terms Relating to Chimneys, Vents, and Heat-Producing Appliances, 2003 ed. http://travelwidpinx.info/nfpa-97-standard-glossar y-of-terms-relating-to-chimneys-vents-and-heat-pro ducing-appliances-2003-edition.html, (Std: Glossary of Terms Relating to Chimneys, Vent, and Heat-Producing Appl - Amer) {241 NFC}