How to Diagnose Strange Noises in a Water Heater

Most of us who own a home are familiar with the variety of strange noises that can be heard throughout our house. These sounds are usually everyday noises such as furnaces turning on and off, water tanks filling up, floorboards creaking, etc., and are nothing to worry about. But what happens when you hear new sounds that aren’t everyday noises? What happens when those new sounds are coming from your water heater? Would you know what to do? Well if you don’t know, here is a brief overview of how a water heater works, and what those strange noises mean.

How A Water Heater Works

Most water heaters consist of a large tank that heats and stores water so it is available when you need it. When you open your faucet, the hot water you use is drawn from the top of the tank, while replacement cold water is pumped into the bottom of the tank through a pipe called the “dip tube”. This replacement cold water lowers the temperature of the water in the tank, so when the temperature of the water drops below a certain point, elements in the water heater turn on to heat the water back up. This cycle repeats itself over and over whenever you use hot water.

Your water heater will produce various noises throughout the day. You may hear a “whooshing” sound from a gas water heater whenever the heating element turns on, or you may hear water running as the cold-water refills the tank. These are normal sounds and are nothing to worry about.

Things That Go Bump in the Night

Some hot water heater problems are announced by unfamiliar noises emanating from your pipes, or from the heater itself. If you know what to listen for, you may be able to correct the problem yourself. Here are some sounds you may hear, what they mean, and how to fix them.

Rumbling / Pounding Noises

When minerals, scale, and sediment build up in the water tank, small amounts of moisture can be trapped at the bottom of the tank. The heat the water tank uses to provide hot water can change the moisture to steam. This steam can build up pressure, causing rumbling and pounding noises. This sediment not only causes annoying noises, but also can shorten the life of the tank itself.

Sediment can easily be removed by flushing out your tank. Start by shutting off the water supply to the tank. Attach one end of a garden hose to the drain valve located at the bottom of the water tank. Open the valve and allow it to drain until only clean water comes out. This will remove any sediment in the tank.

Sizzling / Pinging Noises

When a large amount of hot water is drained from the tank, condensation often occurs due to the large amount of replacement cold water entering the water heater. Sometimes this condensation flows down the outside of the tank and drips onto the hot burner. When this happens, it can cause a sizzling or pinging noise. There is not much you can do to prevent this, and it is typically not harmful to your water heater.

Banging / Hammering Pipe Noises

As the water flows through your pipes, it pushes the air in front of it. When this air reaches a valve or bend in the pipes, a shock wave results creating a loud banging or hammering sound. This is called a “Water Hammer”, and not only is it an annoying noise, but could damage your piping system. Water hammers are typically caused when a valve in the system shuts off suddenly. The best way to resolve this problem is to install a “water hammer arrestor”. You may be able to install this yourself, but you will need to do some “plumbing”, so you may want to hire a professional.

So now you know what all those strange noises coming from your water heater might be, and which ones are normal and which ones require your attention. Just remember; never ignore them, and when in doubt – call in a professional. No one wants a swimming pool in his or her basement.

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