Rheem Gladiator Water Heater Troubleshooting

Rheem Gladiator Water Heater Troubleshooting [6 Common Problems & Solutions]

This is a complete guide on Rheem Gladiator Water Heater Troubleshooting. This article will break down common problems you will encounter over time. They are: 

  • Not enough or no hot water
  • Excessive hot water
  • Can Set Above 140°F
  • Rattling noise during periods of water usage
  • Reset the unit but still gives the leak detection alarm
  • And a lot.

So, let’s dive in. 

Table of Contents

Rheem Gladiator Water Heater Troubleshooting [6 Problems & Solutions]

In this chapter, I will disclose some common problems of the Rheem Gladiator Water Heater and provide their solutions as well. 

01. Not Enough Or No Hot Water

You won’t get enough to no hot water from your Rheem Gladiator due to the following reasons: 

  • Water usage may exceed the heating capacity of the water heater.
  • The circuit breaker gets tripped or a fuse gets blown out. 
  • No electric supply to your water heater. 
  • You set the thermostat too low. 
  • You keep the hot water faucets open. 
  • Improper wiring
  • The auto shut-off valve is in the closed position. 

How To Fix: 

For the first scenario, you should wait until your Rheem Gladiator returns to its normal operation or get recovered after an abnormal demand. 

Secondly, ensure the circuit breaker is in the up position. If it gets tripped, just flip it to the up position. Also, check the fuses to see if any of them gets blown out or not. If yes, replace the fuses with new ones. 

You can’t expect your water heater to heat the water if there is no power. Make sure the circuit breaker is in the on position. If your Rheem water heater comes with a disconnect switch, it should be in the On position. 

Sometimes, you may forget to set the thermostat to a higher setting. Consequently, the water output you get is not hot enough. To get steamy water, you should set the thermostat to a higher setting. 

Just go to the digital control panel to your Rheem Gladiator Water Heater. Then, press the Right arrow until the desired temperature is shown. In this way, you can increase the water temperature. 

To get hot water, every hot water faucet in your house should be closed. If any of them remain open, close the faucets. 

In case of improper wiring, I recommend you call a certified electrician to deal with the wiring issues. 

And lastly, ensure the auto shut-off valve is in the open position. If it remains closed, set it to Open. Follow the below steps to set the auto shut-off valve to Open: 

  • Turn the power off to your hot water heater. 
  • Press and move the auto shut-off valve in the counterclockwise direction until it stops.
  • Take a look at the display and the arrow of the valve position indicator will be pointed to Open. 

02. Excessive Hot Water

Water heater is specially designed to heat water to make our everyday life comfortable by providing steamy water in the winter. 

But what if the water heater generates too hot water? Yes, it’s frustrating!

Setting the thermostat too high is the culprit that causes your water heater to produce excessive hot water. 

How To Fix: 

If you set the water temperature above 125°F, it will burn your skin severely. So, setting the water temperature between 115- 120 degrees will be a safe route. To reduce water temperature, just press the left arrow until the display shows the desired temperature setting. 

03. Can’t Set Above 140°F

If you lock the keypad, you can’t set the water temperature. This feature is helpful because it reduces the chance of unintentional changes in water temperature. Maybe you lock the keypad and forget about it. 

How To Fix: 

Unlocking the keypad will let you change the water temperature again. Press and hold the two arrow buttons for 3 seconds and it will unlock the keypad. Now, you can fine-tune the water temperature by playing with the keypad. 

04. Rattling Noise During Periods of Water Usage

If your water heater is making a rattling noise like a rattlesnake, don’t worry about it. It’s normal when the heat trap fittings are in operation. In short, it’s not a problem and doesn’t require any service. 

How To Fix: 

There is nothing to fix as it is the normal sound when the internal trap fittings are in operation. 

05. Reset The Unit But Still Gives The Leak Detection Alarm

Rheem Gladiator Water Heater has a leak detection system. If there is water in the cold water channel nipple area, it will give the leak detection alarm. To fix this issue, you must collect the water from the area and reset the water heater. But resetting the water heater will bring no luck to you if still there is a tiny bit of moisture in the leak detection area. 

How To Fix: 

You should get rid of the tiny bit of moisture from the leak detection area. It will keep showing the alarm message if you fail to collect the moisture. I highly recommend you to use a hair dryer to dry the small section of moisture. If the area is hard to reach, you can use a shop-vac to blow out the moisture. 

If the problem persists, I bet the leak detection system is at fault. In this case, you must replace it to solve the issue.

06. Rheem Gladiator Flashing 4 Red Blinks

Your Rheem Gladiator will alarm and give 4 consecutive red blinks if: 

  • Wires leading to upper or lower elements get detached
  • Eco gets tripped or need a reset
  • One of the elements are at fault

How To Fix: 

All the issues that cause the water heater to beep and flash 4 red blinks need professional skills to solve. I recommend you call a certified plumber to deal with this problem for you. 

How Do You Reset Your Rheem Gladiator Water Heater?

These simple steps will help you reset your Rheem Gladiator Water Heater: 

  • Turn off the power to your water heater by flipping down the circuit breaker for the unit.
  • Use a Phillips head screwdriver to remove the jacket access panel, electric control, and insulation.
  • Press the red button on the upper thermostat.
  • Replace the insulation, electric control, and the jacket access panel. Ensure you secure the access panel by tightening the nuts. 
  • Restore the power of your water heater.

How Do You Drain a Rheem Gladiator Water Heater?

You can try these step-by-step guides to drain your Rheem Gladiator Water Heater: 

  • Shut off the electric power to your water heater before draining the tank.
  • Turn off the cold water supply. 
  • Open a hot water faucet or lift the handle on the pressure relief valve to release pressure or air from the tank.
  • Attach a garden hose to the drain valve and place the other end to the nearest floor drain or outside. 
  • Open the drain valve to let the water drain. 
  • Once you drain the tank completely, refill the water tank by turning on the cold water supply. 
  • Ensure you close the drain valve. Then, restore the power to the unit. 


Every electric appliance starts malfunctioning over time. And your Rheem Gladiator Water Heater is not an exception to that. And you already know how discomfortable it is if you get no hot water from the unit. 

Fortunately, this guide on Rheem Gladiator Water Heater Troubleshooting will help you solve the common water heater issues. As a result, you can take the necessary initiatives to deal with the problem. 

If this guide fails to solve the problem you encounter, don’t hesitate to reach out to Rheem Customer Service.

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