I just had a new water heater installed and within a few seconds of turning on the hot water, we hear a low rumbling, vibration sound, that will intensify and deintensify within 5-10 seconds. It happens when we use the hot water at any faucet. It also sometimes happens shortly after the hot water is turned off. The water pressure does not seem to be effected.
I called the plumber and he said in 30 years he has never seen this.
Looking on the web, the only thing that comes close, is talk of a problems with the heat traps.
Any advice would be great.