A water pressure reducing valve automatically reduces the pressure from the water supply to a lower, more sensible pressure. Most commonly used in a closed heating system. Water entering the valve from mains is constricted within the valve body and directed through the inner chamber controlled by an adjustable spring loaded diaphragm and disc. Even if the supply water pressure fluctuates, the pressure reducing valve ensures a constant flow of water at a functional pressure, as long as the supply pressure does not drop below the valve’s pre-set pressure.