Rheem Gladiator Water Heater Troubleshooting [Why+ How To Fix]

The most common Rheem Gladiator water heater problems include:

  • The heater is making a rattling noise.
  • Rumbling sound from the heater.
  • No power to the heater. 
  • The heater tank is leaking.
  • Water is not getting hot enough or no hot water. 

Also, producing too hot water, failing to set the temperature above 140°F, popping noise from the relief valve, and alarm from the leak sensor is on the list of heater major problems. 

rheem gladiator water heater troubleshooting

However, go on reading our well-proven guide on Rheem gladiator water heater troubleshooting from where you will get all effective solution methods. 

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Rheem Gladiator Water Heater Troubleshooting [9 Easy Fixes]

Below we have explored all the responsive factors for each appeared a problem that might make your water heater stop working. Also, learn the corrective steps to troubleshoot the problem effectively.

Note: You can also read how to fix the Rheem gladiator water heater service needed light on problems.

1. Water Heater Making Ratling Noise

Rattling noise from the Rheem gladiator water heater is the most common sound that Rheem owners encounter. The noise is quite normal indicating that the heat trap fittings are in operation. 

How To Fix:

As the heat trap fittings are in operation and creating rating noise, thus there is no need for service. 

2. Water Heater Making Rumbling Noise

There are a few major reasons that are responsible for the rumbling noise from the Rheem Gladiator. Building up limescale in the heater metal components is the leading one among them.

rheem gladiator water heater making rumbling noise 

If the mineral particles like calcium and magnesium are stuck up in the heater heating elements, the heater starts creating a strange rumbling sound. The problem is a clear sign that the heater is not operating efficiently. 

How To Fix:

You have to clean out the sediment build-up from the heating elements to fix the rumbling noise issue. Remove the heating elements from the connection and clean it with vinegar solution. Vinegar is a mild acid but quite effective to remove the significant mineral buildup from the metal elements. 

remove mineral from the metal elements

On top of that, you need to be concerned about descaling the buildup of sediment from the heater. Flush your water heater at least twice a year to increase the heater’s efficiency. 

3. Heater Is Not Turning On

Most of the Rheem owner has a common query about the Rheem water heater not turning on. Due to turning on failure, you are surely unable to get hot water. The circumstance is most likely relatable to the electrical sources. 

rheem gladiator heater is not turning on 

The first responsive factor is the circuit breaker of the home. If the Rheem heater has a surge in power, the circuit breaker gets tripped, and the heater won’t turn on. Also, there might be a blown fuse issue.  

How To Fix:

First, turn off the breaker to the water heater’s circuit from the main panel. Now, ensure that all of the circuits are in the right position. If there is no issue with your circuit breaker, look for a blown fuse. Replace the blown fuse.

As the complete tasks are electric work, it is better to contact a professional to carry out the repairs.

4. Rheem Gladiator Water Heater Leaking

Leaking water from the water heater is a signal that something is going wrong in the heater system. The water may start leaking from different places like the top, bottom, or from the tank, water heater nipples, or drain lines. 

defective T&P valve

The possible reasons for a water heater leakage include: loose inlet & outlet pipes, defective T&P valve, leaky vent cap, and corroded anode rod are the culprits. 

Otherwise, there might be a loose drain valve or a damaged inner tank if the water is leaking from the bottom.

How To Fix:

Start troubleshooting by checking the inlet and outlet pipes of the heater. Tightening up the pipe’s connection points. Replace the corroded dielectric nipples. Also, replace the T&P valve if it goes bad.

Monitor whether the water is leaking from the anode rod. You have to replace the anode rod if gets extensively corroded.

rheem gladiator water heater anode rod

If the drain valve is loose, tighten up the valve. Change the damaged drain valve. Most of the time, the inner tank gets damaged because of lacking proper maintenance. Contact a plumber for better suggestions.

5. Water Is Not Hot Enough Or No Hot Water

There are two heating elements in the Rheem Gladiator water heater. One is on the upper side, and another one is on the lower side. If these two essential heating elements get damaged, the output water will not be hot enough. 

Other major reasons that are responsive behind this issue include:

  • The tripped circuit breaker or a blown fuse.
  • Setting the temperature too low.
  • Sediment or rust builds up in the heating element.
  • System overload or using an undersized water tank.
  • Cracks in the dip tube inside. 
  • Closed auto shut-off valve. 
 faulty dip tube

How To Fix:

Here are the simple steps to fix the heating issue on a Rheem Gladiator water heater:

Step 1: First of all, ensure the circuit breaker of your water is not tripped. If so, just flip it back in position. Check for blown fuses as well. 

Step 2: Make sure that you are not using multiple appliances for hot water at one time. Reduce the hot water heater by shutting off some of the hot water fixtures. 

Besides, you can upgrade your hot water tank to a higher capacity if you have a large family. 

Step 3: If the temperature is set too low, raising the thermostat temperature can help to get the water hotter. Set the temperature between 120-140 degrees. 

Step 4: Inspect the dip tube inside of the heater. Replace the defective dip tube. You may need professional help to perform this task.

Step 5: Then, flush & drain the tank to eliminate the sediment built up from the heating element. 

Pro Tips: Install a water softener to prevent sediment build-up in the heater tank for the most part.

Step 6: Check the auto shut-off valve and ensure it is open. If not, just press and move the valve counterclockwise to open it. 

6. Water Heater Getting Too Hot

Sometimes, it is seen that the water from the heater is getting too hot, which is not only just annoying but also quite dangerous. When the water temperature rises higher than usual, be sure that is a warning sign, and you need to be concerned about some factors.

Higher chances are you have set the thermostat temperature too high. If not, A broken thermostat is a leading culprit as the core function of this element is regulating the water temperature. 

Other major reasons would be:

  • A blocked T & P valve. 
  • Sediment has affected the heating elements.

How To Fix:

First up, move through the heater thermostat. Make sure the temperature is not too high. The recommended temperature of the thermostat is 120°F-140°F. Besides, ensure the thermostat is working properly. 

Now check the pressure relief valve whether it gets stuck in the closed position. Simply turn up the lever to release the trapped pressure.

Also, check each of the heating elements of the heater if they are in good working condition. If needed, test the continuity of the heating elements.

 faulty heating elements

If you’re suspecting a higher mineral buildup, better to flush your water heater to dissolve the minerals. In case, still, Rheem gladiator water heater not heating, contact a professional plumber to resolve the issue.

7. Can’t Set Above 140°F

Most of the time, users want to set the temperature higher and fail to set it above 140°F. Although, setting the temperature higher is dangerous as the hot water brings potential hampers to the heating system. 

But if you can’t set the temperature above 140°F, be sure the keypad is locked. Here, you need to unlock the keypad.

How To Unlock Rheem Gladiator Keypad

Go through the below few steps to unlock the keypad:

  • First, press the two arrow buttons from the keypad.
  • Keep holding the button simultaneously for 3 seconds.
  • It will unlock the keypad. Now you can set your desired temperature.

8. Relief Valve Producing Popping Noise Or Draining

Sometimes, a strange draining noise starts coming out from the relief valve. Pressure relief mainly helps to relieve excessive pressure from the water heater tank.

pressure relief valve producing popping noise

But when the relief valve starts creating a popping noise, be sure the hot water trapped beneath the sediment layer is boiling.

Another reason would be high-pressure buildup due to thermal expansion in a closed system. Thermal expansion is the most common condition which exists whenever water is heated. 

When the heated water fails to expand into the public water system because of the backflow device, it pressurizes the relief valve and creates a popping noise.

How To Fix:

As an effective solution, you can drain and flush your water heater tank. If still there is the same sound from T & P valve, be confirm that it’s time to get your water heater out of the thermal expansion condition. 

To do so, contact a professional hand to complete the task. It will be good if you discuss your concerns with a licensed plumber. 

9. Rheem Gladiator Giving The Leak Detection Alarm

There is a built-in LeakSense and LeakGuard technology in Rheem Gladiator which detects leaking water from the system.

LeakSense and LeakGuard technology in rheem gladiator water heater

Whenever it detects a leakage, it sounds an alarm and shut off the heater automatically to minimize water damage.

Anyway, if the leak sensor is giving an audible alarm, be sure there is leakage in your water heater system. The possible causes behind a leak would be:

  • Loose inlet or outlet pipe.
  • Defective T & P valve.
  • Damaged anode rod.
  • Loose drain valve.

How To Fix:

First up, you have to address the leak source of your water heater and fix it. You must have to clear the moisture from the leak detection area. Otherwise, it’ll continuously trigger the alarm. 

Once you’ve cleared out the water from the leak sensor and fixed the problem that is causing the leakage, it’s time to reset the unit. 

How To Reset Rheem Gladiator Water Heater?

Here are the step-by-step instructions to reset your electric water heater:

rheem gladiator water heater reset button

Step 1: First up, turn off the power to the water heater.

Step 2: Remove the user interface control and insulation to access the reset button.

Step 3: Remove the thermostat protective cover as well. You will see a red reset button on the power board and upper sensor assembly. Press the reset button firmly.

Step 4: The complete heater will be reset. Then, place the insulation and user interface control. Finally, turn on the power to the water heater.


What trips the reset button on an electric water heater?

There is a reset button on the upper thermostat of the water heater. Loose electrical connection and creating a substantial amount of heat because of high resistance trips the reset button.

How long does it take for the water heater to heat come back?

Basically, the water heater tank takes 30 to 40 minutes to heat the water. But the water heater and all the heating elements should be working properly. 

Wrapping Thoughts

That’s all we have!! Hopefully, our assigned each of the heater problems with the corresponding reasons have become informative enough for you. 

If you face any problems with your water heater, go through the solution process explained in the above Rheem Gladiator water heater troubleshooting guide. 

Let us know if you face trouble while resolving the issue. We are always ready to help you with the best. 

About William

William is the founder of Fireplacehubs.com. He has real life practical skills in fixing smoker & heating appliance issues. He loves to share his knowledge & helps others in fixing their appliances & saving their money. William firmly believes that anyone can repair his or her unit with the correct guidance & knowledge. See more at about us.

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