Re: Rumbling Pipes
It sounds like water hammer. If you've never had the problem before, then I suspect that the air buffer tubes have become waterlogged. Turn off the house main, open a couple faucets and an outside hose bib for a few minutes. Close the faucets and hose bib and turn the main back on. By draining the water out of the system, you're restoring the air in the buffer tubes which should stop or reduce the noise you're hearing.
I suffer from CDO ... Its like OCD, but in alphabetical order, LIKE IT SHOULD BE!!!