Why Is My Hot Water Heater Whistling?

Hot water heaters are standard in many homes across the United States. With the comfort and luxury they provide, it is customary to want to keep it in tip-top shape. So, when you notice a whistling sound coming from that direction and realize it wasn’t you subconsciously doing so, you begin to wonder. Why is my hot water heater whistling, and is it normal?

You just stepped out after a nice, hot shower. At ease, you begin to whistle a tune, continuing as you walk down the hall. Something distracts you, and the whistling stops abruptly – but keeps going.

Your water heater decided to carry the tune for you, and you’re not sure how to feel about it. Let’s take a look at a water heater and why it whistles (not to mention it’s not even in tune, either).

How Does My Hot Water Heater Work?

First, let’s take a look at how your hot water heater tank works. It is made up of several different parts, all doing an excellent job at bringing you the hot water you need.

It all begins with the dip tube, otherwise known as the cold water inlet. The dip tube brings water from the main line into the water heater, where it begins to warm up. The burner at the bottom of the tank heats the water to the desired temperature.

As the water heats up, it begins to rise to the top of the tank. Then, the heat out pipe, also known as the hot water outlet, exits the water heater, bringing it to your desired location.

Why Is My Hot Water Heater Whistling?

Now that we know the basics of how a hot water heater works let’s take a look at what causes your water heater to whistle. There are a few different reasons that cause your water heater to whistle, and being in a good mood is none of them. Let’s take a look.

Water Inlet or Outlet

One thing that can cause your water heater to start to whistle a tune is the water outlet or inlet. Again, otherwise known as the dip tube or the heat out pipe. Over time, these connections become worn out, and the quality begins to decline.

If the whistle sound occurs when you are running low on hot water, chances are one or both of these connections have gone bad. The heat-out pipe is more likely to go bad than the dip tube, but it is possible to wear both out.

Drain Valve

Another portion of a hot water tank is a drain valve, which, you guessed it, drains the tank. As your hot water tank ages, sediments begin to build up at the bottom of the tank. To drain the sediment is the drain valve (clever name, isn’t it). If the valve is loose, air can pass inside the tank and cause a whistling noise.

TPR Valve

Plumber Fixing Valve

To function properly, quite a bit of heat and pressure are required to build up inside the tank. Usually, safety features in the tank prevent the pressure from building up to dangerous levels. However, because nothing is perfect, a TPR valve is installed.

This valve is known as the temperature pressure relief valve, as it opens to allow pressure to escape the tank, avoiding dangerous levels. When the valve is opened, it can cause a whistle. This is the most likely reason your water heater tank is whistling.

Cracked Tank

Routine maintenance is necessary for keeping your water heater in working condition. However, it is pretty easy to forget to do what your water heater needs to maintain business as usual. Because your water heater is literally made to heat water, it can be prone to rusting over time.

Once the tank rusts, cracks are more likely to occur than not. Whistling can also be caused by the air entering or escaping the crack in the water tank.

How Do I Stop My Water Heater From Whistling?

The best way to stop your water heater from whistling is to call a plumber and have them diagnose and fix the issue. This way, you do not lose your flow of hot water, and you don’t have to worry about any water damage that may occur from improper use (or trying to fix) your water heater.

Is It Bad If My Water Heater Is Whistling?

Considering water heaters weren’t exactly made to whistle, it’s not considered a new hobby when it does start. This noise is a sign of malfunction, and you should have a professional address the issue as soon as possible.

Now, while it is fairly unlikely, it is not impossible that your water heater malfunctioning can cause an explosion. This is one of the main reasons we do not recommend that your work on the tank yourself and contact a professional.

Whistling usually indicates there is too much pressure building up inside the tank and that there are problems with the TPR valve relieving that pressure. A buildup of sediment in the drain valve or cracks can all be a recipe for an explosion.

So, yes, if your hot water heater is whistling, there is a likelihood that it is dangerous and needs service. To be on the safe side, turn the tank off as soon as it begins to make noise, as it will minimize the risk of an explosion, giving the tank time to cool down and release pressure.

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