Is it normal to hear a hum in one part of the house when the pump is running. I've held all the water pipes but the hum does not go away.

Normally, you wouldn't hear anything. It depends on how loud it is, but you should make absolutely sure the flow isn't restricted somehow and this is the cause of the hum. The older circulation pumps were very loud but these are so quiet, you can barely hear the pump when you stand right in front of it.

The pump may hum from a little vibration but as far as making it hum in another part of the house, isn’t common.