Additional features of the 17 3/4" x 17 3/4" square x 30" high unit includes: aluminized steel jacket for high temperature application; top and sides are packed with 2" fiberglass and the bottom is insulated with a special heat pad; heats water at 180,000 BTU/Hr, 3.75 GPM (60R) and 1.87 GPM (120R). The burner has 32 special primary air injection jets for cleaner combustion.