Rheem Gladiator Water Heater Troubleshooting [7 Easy Fixes]

Rheem water heater is in the range of the most energy-efficient and durable water heaters. Also, the heater is incredible in an ample supply of hot water. But sometimes, a few problems may occur in the heater system that creates hassling period for the users.

The most common Rheem Gladiator water heater problems include heater beeping, not turning on, leakage in the heater, and water not getting hot enough. Also, producing too hot water, failing to set the temperature above 140°F, and popping noise created from the relief valve are on the list of heater major problems. 

We are here bringing a well-proven Rheem gladiator water heater troubleshooting guide from where you will get all effective solution methods. So, to deal with any of the above problems, keep an eye on our guide.

Rheem Gladiator Water Heater Troubleshooting [7 Easy Fixes]

Below we have explored all the responsive factors for each appeared 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. Rheem Gladiator Water Heater Beeping

Rheem gladiator water heater beeping is the most common problem that Rheem owners face. A few major reasons are responsible for this issue. Building up limescale in the heater metal components is the leading reason among them.

If the mineral particles like calcium and magnesium are stuck up in the heater, the heater starts creating a strange rumbling sound. Other responsive factors are:

  • Water leakage
  • The heater is overheating
  • High water pressure
  • Faulty thermostat
  • Poor water flow
  • Blocked air inlet
  • The system is overloaded

Follow the below instructions to resolve the beeping issue from your Rheem gladiator water heater:


  • First up, you need to descale the buildup of sediment from the heater. For this, you have to flush your water heater. Here, you may use the hot water mixed with white vinegar for flashing.
  • Then, find any evidence of leakage. Check the leak sensor and ensure a proper wiring connection. If needed, replace the defective sensor. 
  • Clean out the blocked inlet and outlet pipe. Ensure the venting systems are properly installed.
  • Check out the heat exchanger and look for any leaking signs there. Contact the plumber to repair the damages.

2. Rheem Gladiator Water Heater Won’t Turn 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 water heater won't turn 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. 

In most cases, the heater may shut down for tripped high limit switch due to excessive water temperature. Here are included troubleshooting methods that will effectively work in the case of the “Rheem gladiator water heater no power.”


  • 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.
  • At times, the power problem occurs for the malfunctioning of the thermostat. So, you need to concentrate on this element as well.
  • As the complete tasks are electric work, so it is better to contact a professional to carry out the repairs.

3. 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. 

If the leak source is the top, loose inlet & outlet pipes, defective T&P valve, leaky vent cap, and corroded anode rod are the culprit. Otherwise, there might be a loose drain valve or a damaged inner tank if the water is leaking from the bottom.


  • 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.
T&P valve
  • If the water is leaking from the anode rode, the pipe dope on the tread. Place the anode rod back in. 
  • Now, check whether the anode gets extensively corroded. Replace if needed.
  • 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.

4. Rheem Gladiator Water Heater 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:

  • Setting the temperature too low
  • Sediment or rust builds up in the heating element
  • Undersized water tank and high demand at one time
  • Breaks cracks or falls off of the dip tube that is installed inside the tank 
  • Or the tank has a leak


  • First of all, drain the tank and do a flush to eliminate the sediment built up from the heater. Also, install a water softener to prevent this issue for the most part.
  • If the temperature is set too low, raising the thermostat temperature can help get the water hotter, but it should not go above 140 degrees.
  • Also, if you suspect a defective dip tube, replace it.
  • Make sure that you are not using multiple appliances for hot water at one time.
  • If you have an incorrect size water tank, consult a professional contractor to install a correct size water tank.

5. Rheem Gladiator Water Heater Too Hot Water

Sometimes, it is seen that the water from the heater is getting too hot, which is not just annoying and inconvenient but also 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.

A broken thermostat is the leading culprit for this issue as the core function of this element is regulating the water temperature. Other possible reasons are:

  • Sediment build-up in the heating elements
  • The stuck pressure relief valve
  • Failing heater elements
  • Incorrect temperature settings

Now keep your eye on the solving parts to diminish the issue from your heater in the shortest time:


  • First up, move through the heater thermostat. Make sure the temperature is not too high. The recommended temperature of the thermostat is 120°F.
  • Besides, ensure the thermostat is working properly. If not, replace it.
  • Now check the pressure relief valve if it breaks or gets stuck in the closed position.
  • Then, get rid of the mineral build-up and sediment and flush your water heater.
  • 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.
  • If still, Rheem gladiator water heater is not heating, contact a professional plumber to resolve the issue.

6. Rheem Gladiator Water Heater Can’t Set Above 140

Most of the time, users want to set the temperature higher and fail to set it above 140°F. Setting 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, here the keypad may be locked, and it is the only reason for this issue. Here, you need 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.
  • Note: The maximum temperature that goes safety recommendation against scalding is 120 degrees. 

7. Rheem Gladiator Water Heater Relief Valve Producing Popping Noise

Sometimes, a strange draining noise starts coming out from the relief valve. Pressure relief is an essential valve in the water heating system located near the bottom of the heater. The main function of this valve is relieving excess pressure in the water heater tank.

The relief valve creates a popping noise due to pressure buildup caused by thermal expansion in a closed system. Thermal expansion is the most common condition which exists whenever water is heated. 

The heated water fails to expand into the public water system because of the backflow device. This creates excessive pressure in your water which pressurizes the relief valve and creates the popping noise.


To diminish the excessive pressure from the relief valve, you have to get your water heater out of the thermal expansion condition. You need a professional hand to complete the task. It will be good if you discuss your concerns with a licensed plumber. 

How To Reset Rheem Gladiator Water Heater

In several cases, you may need to reset your Rheem gladiator water heater. The heater features a leak detection system. When the water enters the cold water channel nipple area, it will give the leak detection alarm. You need to collect the water from the area and then reset the water heater. Here are the instructions to reset your electric water heater.

  • First up, turn off the power to the water heater.
  • Then, you have to remove the user interface control and insulation to access the reset button.
  • Remove the thermostat protective cover as well. You will see a red reset button on the power board and upper sensor assembly.
power board and upper sensor assembly
  • Press the reset button.
  • The temperature limiting control of the hater 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. 

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