I am woken up to the sound of a loud popping or thumping in my pipes around 6 am everyday. The sound seems to travel just a bit then goes away. I am the only one at my house and it is always around the same time and before I have gotten up. I talked with a contractor and he said it sounds like air is in my pipes and I am going to need to install.......something, I cannot remember. Of course, this is the same house that has the toilet water connected to my water heater so that everytime I flush, the water heater fills it back up. Very strange. Any suggestions?