Aerco B-plus Indirect- Packed Water Heater. Model: SW1B+09. S/N: H-88-753. National Board: 19512. Style: 110311. MAWP shell 235 psi. at 400°F, spiral tubes 250 psi. at 400°F. Shell thick: 0.188, Head thick: 0.4375. Water heater dimensions: 13-1/2 in. dia. x 48 in. L. Control box with two gauges in the outside; 1st shell outlet, 2nd steam pressure, start/stop indicator, Control box inside components: (2) Gauge from 0 to 30 psi., Limit control set at 20°F minimum above the operating temperature control. Inlets/outlets in the bottom: (2) 3 in. threaded female for the tank, 4 in. threaded female, 2 in. threaded female for the heat spiral tubes. Inlets/outlets in the top: Aqua stat, water solenoid, cutler: 3 in. dia, thermometer line, thermostat, relief valve: 1 in. dia, set 150 psi. at 210°F. Overall dimensions: 24 in. L x 22 in. W x 85 in. H. (ACN191).