Why is my water heater whistling?

It’s not always easy to explain what’s wrong with your plumbing. Over the years we’ve heard “my garbage disposal sounds like it’s full of glass”, “my toilet keeps groaning”, and “my drain sounds like its gargling mouthwash.” We’re used to hearing all kinds of things, and our expertise is in helping our customers to discover what the root of the problem is.

Not too long ago, we had a customer call in with one we’ve only heard a few times before: “Why is my water heater whistling?”

Water heaters can cause and experience some pretty strange issues, and there are actually a couple of problems that could make a water heater whistle. Some of them are more serious than others, and they’re not always easy to tell apart. Read on to learn what your water heater is trying to tell you, and if you should worry.

Possible Causes

The first step to fixing the problem is identifying why your water heater is whistling. There are several reasons this could happen, so you’ll have to have someone perform an in-depth inspection of your water heater.

  1. A crack in the tank.

A cracked tank is a serious issue, and you’ll definitely want someone to inspect all around your tank for any cracks and air or water leaks. As air escapes into or out of your water heater tank, it can create a whistling sound.

  1. An open TPR valve.

This is the most likely cause of your water heater whistle. The TPR valve’s function is to open in case the pressure within your water heater ever gets too high, allowing pressure to be released safely via the valve. As pressure and air escape through the valve, you’ll likely hear a whistling or high pitched noise coming from your water heater.

  1. An open drain valve.

The drain valve is located at the base of your water heater, and it exists to allow you to drain water and residue from your water heater tank. Similar to the TPR valve, if you didn’t close the drain valve all the way, it could be letting air leak out or in, causing a whistling water heater.

  1. A worn inlet or outlet.

Check to see if your water heater whistles only when running hot water. If so, it could be that the connections for the cold water inlet or hot water outlet at the top of the unit are wearing down, letting air escape.

What to Do About a Whistling Water Heater?

Once you’ve diagnosed the issue, don’t wait around. You might enjoy the melody of your whistling water heater, but it can be a serious safety hazard.

  1. Turn off the water heater. The first thing is to turn off the water heater before performing any inspection, especially of electrical components.
  2. Check all the valves. Check the water supply, TPR, and drain valves and ensure they are fully closed or open.
  3. Call a professional. If you aren’t able to diagnose and repair the problem yourself, call your local professional for water heater maintenance and repair.

Did You Fix a Whistling Water Heater?

Simpson Plumbing has years of experience repairing and replacing residential water heaters and commercial water heaters alike. If you’ve had a water heater whistling in the past and were able to successfully diagnose and fix the issue, let us know in the comments.