AO Smith Water Heater Beeping – Causes + Fixes!

Water heaters typically beep to indicate an underlying problem—but just what that problem is depends on the number and sequence of beeps the heater emitted. Did it beep once? Twice?

AO Smith water heaters may emit beeping sounds if there’s a gas or water leak, a faulty sensor, leaking pipes, or low gas levels (in gas-powered units). It may also beep if the unit is overheating. A unique frequency indicates each problem.

If one of these sounds like it may be the cause of your appliance’s beeping, be sure to look up the beeping pattern of that problem to verify. This article will reveal the underlying issues that can cause those beeps.

Reasons Why Your AO Smith Water Heater Keeps Beeping, and How to Fix It! 

AO Smith water heaters may create beeping sounds due to the following reasons:

Gas or Water Leak

Beeping sounds may indicate a leak, which might be a water or gas leak. Water leaks are mostly obvious since you’ll notice water pooling at the base of your unit. However, gas leaks are more difficult to spot. 

For water leaks, the beeping sounds themselves initiate the water heater shutoff feature, which minimizes the leak. For gas leaks, you need to contact your gas company. And don’t forget to ventilate the area before the repairer arrives. 

Your Unit Is Overheating

Sometimes, you get these warning sounds when your internal tank is overheating. The internal temperature of your unit shouldn’t exceed 200 degrees. A faulty thermocouple is often the reason for overheating in water heaters. 

Overheating water heaters may explode, cause fire outbreaks, or damage sensitive internal components. So, try turning off the thermostat to see if the beeping stops—and to protect your home and appliance from fire damage.

Excessive Mineral Deposits

After a few years, calcium and magnesium deposits will cover the heating element. You’ll probably experience this more rapidly if you use a hard water supply. These deposits can also reduce your unit’s heating efficiency.

So, use a descaler to remove mineral deposits from AO Smith tankless water heaters. To descale the water heater, follow the instructions outlined below. 

How to Descale AO Smith Water Heater 

  1. Use your preferred descaler solution, pump, hose, and bucket. 
  2. Unplug the water heater from the power outlet and shut off the gas valve. 
  3. Shut off the hot and cold isolation valves. Note that shutting off the isolation valve separates the water heater from the main water supply.
  4. Remove the caps from the service valves. Leave them in the off position.
  5. Mix one gallon of water with one quart of descaler solution in a bucket.
  6. Connect one end of the hose to the cold service valve and the other to the pump.
  7. Place the pump into the bucket. Remember to cover the pump with a filter.
  8. Connect another hose to the hot service valve, with the hose’s other end in the bucket.

Well done! You’ve successfully descaled your water heater. 

Faulty Sensor

Sometimes, it’s all a false alarm. Check to see if there’s a gas or water leak. Wrap a dry rag around the water pipe to detect small water leaks. Smell for any rotten-egg stench, as propane gas smells like rotten eggs. If you don’t find any leaks, consider fixing the sensor.

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Blocked Air Intake

AO Smith hot water heater models, like the Signature 300, have ventilation grills to help stabilize the unit’s water temperature. As such, it needs an excellent airflow to support combustion

Try checking your ventilation grill once you hear the beeping sound. Note that water heater units in dusty environments are more likely to have blocked air vents. 

ao smith water heater

System Overload

Sometimes, the beeping sound results from system overload in tankless units. There’s a limit to how much hot water these units can supply per minute. Therefore, opening multiple hot water faucets simultaneously can overload the system. 

Unit Is Low on Gas or Water

Note that this only applies to gas-powered heaters. Your unit might beep when the gas is about to run out. 

Too Much Water Pressure

There are instances when the pressure of water entering your house suddenly increases. Since tankless water heaters have a maximum pressure limit of 150 psi, anything above the max limit will overload the system. 

So, you may hear beeping sounds when the pressure is too high for the unit to handle. 

Overall, these beeping sounds are warnings of impending damage. Sometimes, the unit may display error codes while beeping. The error codes assist you in diagnosing the damage accurately. Don’t forget to check the user manual for information on these error codes. 

Note: Don’t open up the unit until you have diagnosed the problem. 

How Can I Stop My AO Smith Water Heater from Beeping?

As mentioned in the previous section, there are multiple causes of beeping sounds in these types of heaters. The best fix depends on the source.

In this section, we’ll explore how to reset AO Smith water heaters to stop beeping sounds. Performing a reset helps you to return the unit to its original settings. It’s often the last step after a repair. 

How to Reset AO Smith Water Heaters

  1. Switch off the unit from the main power switch. 
  2. Next, wait a few minutes before unscrewing the top panel on the water heater. 
  3. In most AO Smith heaters, you’ll see a white foam covering the reset button and other essential components. 
  4. Pull back the white foam, and press the red button to reset the heater. 
  5. Now, switch on the main power switch. The beeping sound should stop. Call a licensed AO Smith licensed repairer if the noise persists. 


Your AO Smith water heater beeps when there’s an underlying problem with the unit. Consider all the possible causes listed above before digging around in your appliance, and always be sure to consult with a professional when needed.