Used 870 Sq. Ft. Horizontal SS Spiral Heat Exchanger, Mfg by American Heat, S/N: 15472. Rated 75 PSI @ -20 to 200 deg F. Inner Pass: .3125" x 72"; Outer pass: .3125" x 72"., Thickness: SA515-70 Head: 1.15", SA240-304L Shell: .125". (4) 4" ports, 2 on ends, 2 on sides, 6 lifting eyes.