Water Heater Making Noise? What Each Sound Means
Rumbling and popping: sediment
This is the most common water heater noise and the most worth acting on. Minerals settle out of the water and collect on the bottom of the tank. On a gas heater the burner is underneath that layer, so it heats the sediment as well as the water, and pockets of water trapped underneath boil and force their way up. That is the popping.
The problem is not the noise. It is that the sediment layer insulates the burner from the water, so the heater runs longer for the same result, costs more to run, and puts the tank bottom under thermal stress it was not designed for. Heaters with heavy sediment fail years earlier than they should.
Caught early, a flush resolves it. Left long enough, the sediment hardens and flushing stops being effective.
Ticking or tapping: usually harmless
A regular tick shortly after a hot water draw is normally pipes expanding and contracting against framing or straps. It is a comfort issue rather than a fault, and it can often be resolved by adjusting a strap or adding padding where the pipe passes through wood.
It can also be the heat trap nipples on top of the heater, which is also harmless.
Screeching or whistling: restricted flow
A high-pitched sound generally means water forcing through a partially closed valve. Check that the inlet and outlet valves at the heater are fully open, and that the temperature and pressure relief valve is not partially open.
A T and P valve that is discharging is not a noise problem. It means the tank is over temperature or over pressure, and it needs looking at promptly.
Banging when a tap shuts off: water hammer
A bang immediately after a valve closes is water hammer — the momentum of moving water stopping abruptly. It is not the heater itself, but it is worth resolving because the shock stresses joints throughout the system. Arrestors or a properly charged expansion tank usually deal with it.
The one to act on quickly
Any noise accompanied by water around the base of the heater changes the priority. A leak at a fitting is a repair. A leak from the tank body means the tank has failed internally and it will get worse, not better. Shut off the water supply to the heater and call (833) 435-9778.