Need a Water Flow Meter? We Have The Best Range of Electromagnetic Options! The water flow meter is one of the oldest components in HVAC environments, and is critical to the monitoring and health of your systems. For many years, electromagnetics has been the default technology used in a water flow meter, and at ControlStore we stock a wide range of industry-leading options for any environment. The technology that goes into a water flow meter is quite simple. The coils of the electromagnetic meter, once installed, generate a magnetic field orthogonal to the water flow direction. When a liquid passes through the magnetic field, it creates a current, which the sensors then measure the voltage of. The higher the flow velocity, the higher the voltage reported. It’s that simple.