Why is my water heater whistling? Find out what causes high-pitched noises

Is your water heater making whistling noises that have you worried? A water heater making loud noise, whether it’s a whistling, hissing, or tapping sound, can be annoying and concerning. These noises can indicate a variety of issues, ranging from simple fixes to more serious problems. We’re here to help you figure out what the problem is and how to fix it like a Pro!

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Important: The information provided in this article may not apply to your specific appliance model. While we strive to offer helpful advice for DIY appliance repairs, variations in models and configurations can lead to differences in troubleshooting steps, error codes and part replacements. For the most accurate guidance, we strongly recommend consulting the technical sheet for your specific appliance model.

Common causes

When your water heater is making a whistling noise, it can vary in intensity and occur at different times. The sound is often high-pitched and may come and go as the water heater cycles on and off.

Several issues can be the cause of the water heater making a whistling noise or the water heater making a hissing noise. Below are the most common reasons why your water heater may be producing these high-pitched sounds:

Sediment buildup in the tank

Over time, minerals like calcium and magnesium from hard water settle at the bottom of the tank. When the water heats, steam bubbles form under the sediment, which can escape as a high-pitched whistling or hissing noise. Not only does this reduce your heater’s efficiency, but it also causes annoying noises.

Faulty pressure relief valve

The pressure relief valve is an essential safety feature that releases pressure from the water heater when it builds up too high. If this valve is faulty or malfunctioning, it can cause your water heater to make a whistling noise as pressure is released from the tank. This is often seen in older water heaters or units that have not been maintained regularly.

Restricted airflow or vent blockage

A gas water heater relies on proper ventilation. If the vent is clogged or blocked, it may cause the heater to emit a whistling noise as air struggles to pass through. This restriction can also cause overheating, which could result in a water heater making hissing noise.

Leaks in the water heater

Leaks, especially around the pressure valve or pipes, can cause a water heater to make a hissing noise. As water escapes through these leaks, it may create air pockets that whistle when water flows through them. Small leaks can lead to larger problems over time.

Water flow restriction

A partially closed valve or sediment buildup in the pipes can cause water to be forced through a small opening, resulting in a high-pitched whistling or tapping sound.

Solutions

Now that we’ve identified the causes, let’s look at solutions to stop your water heater from making a loud noise and restore quiet to your home.

1. Flush the water heater tank

1. Turn off the water heater and let it cool down. For gas heaters, set the gas control valve to the “pilot” position.
2. Locate the drain valve on the tank. It is typically located near the bottom and looks like a hose bib with a threaded end.
3. Attach a garden hose to the valve and run it to a drain, utility sink, or outside.
4. Open a hot water faucet in your home to allow air into the system and help with drainage.
5. Open the valve and allow the tank to drain completely. Be cautious as the water can be hot.
6. To further flush the tank, turn the cold water supply back on for a few minutes while the drain valve is still open. This helps to flush out any remaining sediment that may be settled at the bottom of the tank.
7. Once the water runs clear and you have flushed the tank adequately, close the drain valve by turning it clockwise.
8. Disconnect the hose from the drain valve.
9. Turn on the water supply to refill the tank. Keep the hot water faucet open to release any air trapped in the system.
10. For electric heaters, switch the power back on at the breaker box. For gas heaters, set the gas control valve back to the desired temperature.

2. Check and replace the pressure relief valve

1. Before starting any maintenance, ensure the water heater is turned off, and the water inside has cooled down to prevent burns.
2. Have a bucket, towels, and plumbing tape on hand.
3. The pressure relief valve is typically located on the top or side of the water heater and has a long handle or lever. Lift the lever on the pressure relief valve to allow a small amount of water to release. This tests if the valve is working correctly.
4. If water does not flow out or the valve continues to leak after releasing the lever, the pressure relief valve may be faulty and needs to be replaced.
5. Connect a hose to the drain valve at the bottom of the water heater to drain a few gallons of water, reducing pressure inside the tank.
6. Once the water heater is drained, use a pipe wrench to unscrew the old pressure relief valve from the tank.
7. Wrap the threads of the new pressure relief valve with plumbing tape to create a tight seal.
8. Install the new valve by screwing it into place and tightening it securely.
9. After replacing the valve, turn the water and power back on to the water heater.
10. Lift the lever on the new valve. Water should flow out of the valve.

3. Clear blocked vents and improve airflow

1. Locate the venting system connected to your hot water heater. Vents are typically located on the top of the heater and carry exhaust gases outside.
2. Before performing any maintenance, turn off the hot water heater and allow it to cool down to a safe temperature.
3. Use a vacuum cleaner with a hose attachment to remove any debris or dust around the hot water heater.
4. Ensure there is adequate ventilation around the hot water heater. Clear any clutter or obstructions near the heater that may hinder airflow.

4. Fix leaks

1. Inspect the hot water heater to locate the source of the leak. Check for water pooling around the base of the heater, dripping from connections, or moisture on the tank.
2. Before starting any maintenance, ensure the water heater is turned off, and the water inside has cooled down to prevent burns.
3. Check all connections, including inlet and outlet pipes, fittings, and valves for leaks. Tighten any loose connections using appropriate tools to stop the leaks.
4. For small leaks in the tank or fittings, use a suitable sealant or epoxy designed for hot water applications. Apply the sealant as per the manufacturer’s instructions.
5. If the leak is coming from a damaged component such as the heating element, gasket, or tank itself, these parts may need to be replaced. Follow the manufacturer’s guidelines.
6. Check the tank for signs of corrosion or rust, as this can lead to leaks. If the tank is severely corroded, it may need to be replaced to prevent further issues.
7. Ensure the pressure relief valve is functioning correctly. Test the valve according to the manufacturer’s instructions to prevent excessive pressure buildup.
8. Once the repairs are complete, reassemble the hot water heater, refill the tank, and turn on the water supply. Check for leaks and monitor the heater for any unusual noises or issues.

5. Open or adjust water valves

1. Locate the water valves connected to the hot water heater. These may include inlet and outlet valves, pressure relief valves, and drain valves.
2. Before adjusting any water valves, turn off the power supply (electricity or gas) to the hot water heater and shut off the water supply to the appliance.
3. If the noise is related to water flow, consider adjusting the inlet valve to control the water supply to the heater. Slowly open the inlet valve to ensure a steady flow of water.
4. Check the pressure relief valve for leaks or signs of malfunction. Adjust the valve if needed to maintain the correct pressure in the system.
5. Inspect the connections to the hot water heater for leaks. Tighten any loose fittings or connections to prevent water leakage and noise.

Frequently asked questions

Why is my water heater making a high-pitched whistling noise?

A high-pitched whistling noise from your water heater is often caused by sediment buildup, a faulty pressure relief valve, or restricted airflow. These issues create pressure imbalances or blockages, which result in the whistling sound when the heater is in use.

Is it dangerous if my water heater is making a hissing noise?

A water heater making a hissing noise could indicate steam escaping due to pressure buildup or a leak in the system. While not always immediately dangerous, it’s important to address the issue promptly to prevent potential damage to the heater and avoid safety risks.

How do I fix a water heater that’s making a loud noise?

Fixing a water heater making loud noises like whistling or hissing involves troubleshooting common issues. You may need to flush the tank to remove sediment buildup, replace a faulty pressure relief valve, clear any blocked vents, or fix leaks to eliminate the noise.

Can sediment buildup cause my water heater to make high-pitched noises?

Yes, sediment buildup is one of the most common causes of high-pitched noises in water heaters. Over time, minerals from hard water collect at the bottom of the tank, creating small air pockets that lead to whistling or hissing sounds as steam escapes.

Additional information

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