Honeywell VU53N1017/U 3/4" Two-Way Fan Coil Valve. The VU53 NPT high pressure, Two-Way, Fan Coil zone valves, are used to control flow of hot or chilled water in commercial HVAC equipment such as fan coil units, terminal reheat coils and convectors. 300 Psi Max Static Pressure Rating, 3-Point Actuator Lock. Use With Vu443 Or Vu843 Actuators. IMPORTANT: Not for use in systems containing dissolved oxygen.