Draft Types

A furnace may be constructed with one of many types of draft equipment. Here the term "draft equipment" refers to equipment used to provide and control combustion air. It is linked to the earlier definition we looked at, in the sense that flow of combustion air does effect the static pressure inside an operating furnace.

Natural Draft

The figure shown here illustrates a natural draft furnace. In this type of furnace, no mechanical equipment (such as fans) is used. In this design, draft is created by the natural chimney effect. This type of design is limited to smaller furnaces only.