Direct-fired technology

Thomas Boeckermann, Harold Stevens, Thomas Kuehn, Shawn Manisto, Bill Griffin

Research output: Contribution to journalArticlepeer-review


Beginning with a simple open flame, direct-fired heating is the earliest means of warming structures and occupants. Wood, dung, peat, coal, and oil all made for effective and accessible fuels. However, poor control of combustion and fuel purity produced emissions that could be deadly. So, early civilizations developed indirect heating, separating combustion emissions from the space to be heated. Indirect combustion provides clean, safe heating, but only a fraction of the fuel's heating value is used for useful heating. The remainder is lost through the flue. To increase energy efficiency and to conserve natural energy sources, we need to look at the modern-day applications of direct-fired heating systems.

Original languageEnglish (US)
Pages (from-to)16-26
Number of pages11
JournalASHRAE Journal
Issue number9
StatePublished - Sep 1 2015


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