soft, raised surface upon cloth, mid-14c., downy plumage, from Anglo-French pyle or Middle Dutch pijl, both from Latin pilus a hair (source of Italian pelo, Old French pel). Phonological evidence rules out transmission of the English word via Old French cognate peil, poil. Meaning nap upon cloth is from 1560s.
Updated 01/08/17. 1  of 06. Gas Furnace Types and Efficiency Ratings BanksPhotos / Getty Images The gas furnace in your home is a critically important appliance and one you depend on to work reliably, efficiently and quietly. 2  of 06. Low Efficiency Furnace: 55% to 72% AFUE (obsolete technology) Characteristics. 3  of 06.
Two, three and multi-stage vs. single stage furnaces. Old single-stage gas furnaces are being replaced by a newer type of gas furnaces: multi-stage furnaces, with air sealed combustion and variable speed motors. These new furnaces offer versatility and can increase comfort and energy savings.