The Low Pressure Switch ThermalFlo Titanium Heat Pump is a product manufactured by Pentair, designed specifically as a flow switch for pool and spa systems. It is a crucial component for maintaining proper water flow and pressure within the system, ensuring efficient operation of the heat pump. The part number for this switch is either PUR-151-3656 or 473656, providing a reliable solution for controlling the flow of water in your pool or spa setup.