I replaced my single handle shower valve as it was not sending all of the hot water to the shower head thus it was not sending enough hot water to shower. The newe valve is sending the hot and cold effectively but now the valve makes a humming sound for about 30seconds when it is first turned on. Any suggestions would be great.

What brand/model did you install? This sounds like a vibrating washer or seal.

Does it make the sound when using either tub spout or shower head, or only when using shower head?