1998 Hot Water Set with Shell and Tube Heat Exchanger. Armstrong shell and tube heat exchanger, surge tank, and pump trap. 1999 Tank: National board number 77591. MAWP: 125 psi at 240 °F. MDMT: 18 °F at 125 psi. Size 60. 1998 Armstrong heat exchanger certified by S.A. Armstrong limited. Tube Side: 150 psi, 375 F, 150 psi. Shell Side: 150 psi, 375 F, 35 F, 150 psi. S/N 101204, Model S-64-2-2. Surge Tank: max pressure 160 psi; max temp: 350 °F. Armstrong Pump: Model 2X1X10 4280. Pump capacity: 35 gpm; 80 foot of head. Motor: 3 hp, 1,800 rpm. Impeller dia: 8.897. Pressure gauge: 100 psi.