If your water heater is rumbling, popping, or making other noises, this expert guide will help you troubleshoot and solve the problem. Includes DIY repairs for both gas and electric water heaters.
Hot water heater noises may have any of several causes. A noisy water heater is usually an indication that minor maintenance is needed. Few are a serious concern.
In this article, you’ll find some of the more common water heater noises and the steps you can take to eliminate them.
When the cold water supply is heated, dissolved hard water minerals recrystallize and form scale and sediment. The “harder” your water is (see How to Test for Hard Water), the faster these mineral deposits form.
The scale cakes onto interior surfaces and accumulates as sediment buildup at the bottom of a storage water heater tank.
To minimize the amount of scale in your water, you can have a plumber install an anti-scale system on your water line. This system keeps the minerals suspended in the water so they are less likely to stick to the water heater equipment.
The most complete way to control hard water minerals is to combine an anti-scale system with a water softener, which removes minerals from your water.
As discussed in the article How a Storage Water Heater Works, a water heater has a magnesium or aluminum anode rod inside to minimize corrosive minerals. This is inserted through the top of the tank.
Rumbling, Popping, or Crackling Noise
If it sounds like gravel is boiling in the bottom of your gas water heater’s tank, well—in some ways—it is. But the “gravel” making that rumbling noise is actually sediment from minerals and hard water scale.
As the sediment at the bottom of the water heater tank is heated by the burner directly below it, it gets hot. Then the sediment can roil and tumble. This makes a rumbling sound.
Or, when the gas burner fires, it boils the water that is trapped under the sediment. The result is a popping noise.
The solution to these problems is to flush your water heater.
This rumbling or popping sounds don’t mean that your water heater is dangerous. But, it does indicate a problem. Because the burner’s heat has to travel through the layer of sediment to reach the water, the water heater’s efficiency is reduced.
In addition, chunks of scale can break away from a water heater’s inner surfaces and travel through the hot water pipes. These chunks can jam at a juncture, impeding water flow.
This is why it’s important to flush the tank every few months.
In an electric water heater, scale eventually coats the heating elements inside the tank. As the elements get hot, they cook the scale and the water trapped beneath it. The result can be a water heater popping noise, crackling noises, or sizzling sounds.
The solution in an electric water heater is to replace the heating elements. For more about this, see Water Heater Repair & Troubleshooting.
Vibration or Humming Noise
A vibration noise in a gas water heater is usually caused by a defective burner at the bottom of the tank. Metal plates or fins inside the burner can deflect over time and rub against each other when the burner is on, causing a humming sound or vibration.
This video shows how to fix the vibration by simply bending or trimming a metal bracket that’s near the burner. Be aware that making the type of repair that he shows may void your warranty. Following this video, you can also replace the burner yourself.
For more, see Water Heater Repair & Troubleshooting.
Sound of Water Boiling
If it sounds like the water is boiling inside your water heater tank, turn down the water heater’s temperature.
Next, test the T&P valve to make sure the water heater can release built-up pressure. Lift its lever and make sure hot water comes out of the discharge pipe. Then release the lever. It should snap back down.
If it doesn’t work, the T&P valve may need to be replaced. See How to Replace a Water Heater T&P Relief Valve.
If this is not a job you want to take on yourself, call a water heater service person or a plumber. This could indicate overheating and a dangerous pressure buildup.
Video of Water Heater Noises
This very helpful video by a professional plumber walks you through most of the water heater noises you might encounter.