HVACR Glossary

Draft
The movement of air into and through a combustion chamber; breeching, stack, and chimney. Draft may be natural, resulting from the difference in density of the heated air rising through the stack and the cooler displacing air. Artificial draft may be provided by mechanical means. This could be either induced draft or forced draft. Draft is affected by chimney height, temperature difference, cross section, wind, make-up air opening in the furnace room, and weather conditions. Also see forced, induced, mechanical, natural, and overfire draft.