I have a plumbing issue that I'm looking for suggestions on. After using a substantial amount of hot water (say, a long shower + washing laundry) I will hear a loud rumbling / vibrating sound throughout the house, emanating from the water pipes. The noise seems to originate from the pressure regulator on the main water supply. If I open a hot water tap while the noise is occurring it will immediately stop. (The meters show that no water is flowing while the noise is occurring.)
I suspect that thermal expansion of hot water is causing backpressure on the regulator, and the noise is vibration as the seals in the regulator have water pushed past them.
My current plan is to get a pressure gauge and replicate the issue by nearly-emptying the hot water tank and letting it fill and heat. This should allow me to see the pressure swing in the system. Then based on what I see for the low and high pressures, consider the following options:
- Decrease overall water pressure in the house so post-thermal-expansion it does not push back through the regulator.
- Decrease hot water heater temperature (it's now around the recommended maximum of 130F-ish) to decrease thermal expansion.
- Add an expansion tank to the hot side of the heater.
Does it sound like I'm on the right track?
Best Answer
We had similar issue with hot water heater. Went through three of them in 15 years. Plumber confirmed issue was related to thermal expansion. Consider getting a thermal expansion tank on the supply side of the water heater. If your water company installed a check valve on their side of the supply to the house, to eliminate backflow in to the city water suppy, your thermal expansion is stressing the holding tank in your water heater. That can compromise the tank integrity, causing leaks and flooding from a ruptured tank.