25K BTU FURNACE 25K BTU FURNACE Providing maximum heating performance in a small 12-volt DC furnace, the SF model is offered in four capacities from 20,000 to 35,000 BTU/h input. Only 7 1/2" inches high, it can be easily installed in low height or basement areas that might otherwise just be unused space. Eleven duct connection choices (top, side and bottom) make the SF easy to apply. This furnace can be installed with only a flush mounted vent cap on the exterior wall or be installed with the optional exterior door (Col. White or Polar White) for service access without entering the coach. This unique feature makes the SF model the most versatile furnace on the market. Quiet burner operation, sealed forced-draft combustion, energy saving direct spark ignition, low amp draw and almost limitless design flexibility make this Dynatrail furnace a real winner. Dimensions: 7 1/2"H x 17"W x 20"D. Includes vent kit for 1 1/2" wall. Duct Collars & Thermostat Must be Ordered Separately.