Water heaters make a variety of noises, but not all noises are cause for alarm. Since your water heater is a vital part of your home, however, it is important to understand what to listen for when you hear those sounds.
Here are some common noises and what causes them:
This is caused by sediment collecting in the bottom of the water heater and around the element tubes. Hot water bubbles up through the sediment and makes a popping sound. It is the most common reason for a noisy water heater.
Sediment being stirred by the water flow inside the tank creates a rumbling sound that can indicate that the tank is rusting out and will develop a leak. Once a leak in the tank occurs, the water heater needs to be replaced. To prevent sediment from building up, flush out the water heater periodically. Installing a water softener can also eliminate sediment build-up.
The heating element in an electric water heater is typically placed vertically in the tank. Water flowing around it can cause vibrations that create a humming noise. Tightening the element can fix the problem.
Knocking sounds come from pipes heating internally and is known as “water hammering.” When water entering or exiting the tank is abruptly shut off, the pipes can move and bang against interior walls or studs. Typically caused by a washing machine, dishwasher or toilet. This is not harmful to the water heater, but it can damage the walls. A water hammer arrestor can be installed between the device and the water heater to correct the issue.
This occurs when a valve is not fully opened at the water heater or an outlet (usually a sink). The sound comes from water being forced through the small opening.
Heat traps or check valves installed in water heaters to prevent water from flowing in the wrong direction can cause a ticking or tapping sound. Similar noises occur when hot water in the plumbing cools down.