Hello, I have a question regarding a humming pressure regulator. I recently moved into a old home that had no pressure regulator for the domestic water supply. I installed a new Watt pressure regulator factory set at 50psi. After installing, the regulator makes a humming sound when any faucet is turned on at low volume. As soon as the volume is increased, the noise immediately vanishes. It comes from every place water can be drawn from. Can someone tell me what I need to do in order to eliminate this noise??? Would installing a small expansion tank help??