Horizontal Furnace
Horizontal furnaces (Figure 10-4) are designed for installation in low, cramped spaces. They are often installed in attics (and referred to as attic furnaces), where they are positioned in such a way that a minimum of ductwork is used. This type of furnace is also frequently installed in crawl spaces.
Although dimensions will vary slightly among the various manufactures, the typical horizontal furnace is about 2 ft wide by 2 ft high and 41⁄2 to 5 ft long.
The terms used in this classification system (upflow furnace, downflow furnace, etc.) are commonly employed by furnace man- ufacturers in the advertising literature describing their products. This is equally true of their installation and operation manuals. Because of the widespread usage of these terms, they will be employed in the more detailed description of furnaces in the fol- lowing chapters.
