The pump matches motor speed to system demand. As more liquid is needed, the pump adjusts in real time to increase flow, depending on the number of valves or faucets in operation. Conversely, as demand lessens, the motor slows to a quiet speed while still maintaining a steady system pressure. The smooth performance eliminates the need for an accumulator tank. Sensor VSD pumps operate on installations for either 12 or 24-Vdc electrical systems. Several models are available with flow rates up to 4.5 gpm at pressures to 40 psi. Plumbing for the VSD water-pressure system has no pulsation, water hammer, or temperature swings.