Trane natural gas furnaces have a height of 40 inches and a depth of 28 inches. The width ranges between 14.5 inches and 24.5 inches, depending on the specific model. Trane's smallest gas furnace available belongs to the XB80 series.
XB80 models with a 14.5 width are available in output capacities of 31,000 BTU and 47,000 BTU, with 80-percent efficiency. Trane also manufactures oil furnaces belonging to the XP80 and XV80 series. XP80 model heights range from 41.5 inches to 61.25 inches, with 22.25 inch widths. The depth ranges from 22.25 inches to 47 inches, depending on the specific model. XP80 models are up to 85 percent efficient with a four-speed blower motor. The XV80 oil furnace model is available in more compact dimensions, at a height of 22.25 inches, a depth of 61.25 inches and depth of 22.25 inches. These variable-speed furnaces are up to 85-percent efficient, with an output capacity of 87,000 BTU.