A Rheem tankless water heater that has been properly maintained functions correctly the majority of the time.

In the event that they malfunction, you will, nonetheless, on occasion be required to reset them.

The method of resetting a tankless water heater manufactured by Rheem is simple, risk-free, and uncomplicated.

First things first, check to see whether the device is switched on.

After that, open the front panel to access the reset button, which should be a red button located near the thermostat.

Maintain the downward pressure until you hear a click.

It is expected that the unit will resume regular functioning.

The following provides an overview of the different reasons why you may need to reset your Rheem tankless water heater, as well as the detailed steps for doing so and answers to any frequently asked questions that may be relevant.

Rheem’s Professional Series Tankless Water Heating and Cooling System

Why Do I Need To Keep Reverting My Tankless Water Heater Back To Its Factory Defaults?

The following is a list of potential explanations for why you have to continuously resetting your Rheem tankless water heater.

#1. Overloading

The amount of hot water that can be stored in a water heater varies.

If the unit detects that you have a larger demand for hot water at a certain moment in time than it is able to provide, it will only offer cold water to you.

It’s possible that the unit may continue to produce cold water even if you turn off certain taps or appliances.

The remedy would be to restore it to its factory settings or the settings it had when it was first manufactured.

#2. The Button For The Reset Keeps Tripping.

The majority of water heaters’ most important safety function is the reset button.

The remote button will trigger and turn off power flow if specific components of the machine are not functioning as they should be.

Because of this, the functioning of the unit is stopped, which averts future problems, such as the risk of fire when the heater is operating at an unsafe temperature.

Checking the electrical panel will allow you to determine whether or not the reset button has been triggered.

Find the circuit that is labeled “water heater,” for instance, and determine if it is turned on or off.

In most cases, when you press the reset button, the circuit breaker will also trip.

As a direct result of this, the socket turns off.

The following is a list of the most typical causes of the reset button on your Rheem water heater to trip:

  • Thermostat with a malfunction
  • Unsecured connection in the wiring.
  • The heating element experienced a short circuit.
  • Incorrect button for the reset
  • High-limit switch with a malfunction

#3. If an Error Code Is Being Displayed As an Option

The only indication that a Rheem water heater has a problem is when it shows the appropriate Rheem error number, which may happen on occasion.

On other occasions, it could shut down the device and perform a reset on it.

The following is a list of the Rheem water heater fault codes that are the most prevalent and may cause the reset button to trip:

  • Error code 00 – Continuous water heater
  • Error code 05 – Inadequate passage of air into the combustion chamber, maybe due to clogged vent exhaust.
  • Error code 11 – Ignition failure caused by partly opened or closed valves, high gas pressure and volume, an open or short-circuited gas solenoid valve, or a malfunctioning igniter.
  • Error code 12 – Flame Failure. This error indicates that the tankless unit has not detected a flame in its surrounding environment. Due to safety concerns and the desire to avoid harm, the system has malfunctioned.
  • Error code 13 – This is exclusive to indoor Rheem tankless devices. It is a sign of faulty combustion, which may have been brought on by a broken flame rod or fan motor, or by a restriction in the air intake.
  • Error code 14 – Overheated film wrap, which might be caused by a limitation in airflow to the combustion chambers, a malfunctioning heat exchanger, or foreign objects in the combustion chambers and exhaust pipes.
  • Error code 15 – Indicates that the heat exchanger has been working at a temperature of 207F or higher for more than 15 seconds. This might be the result of limescale buildup within the unit, a blocked cold water intake line, a defective heat exchanger thermistor, a partly open or closed water heater inlet valve, or any combination of these factors.
  • Error code 16 – Indicates that the temperature of the output water is higher than the thermostat setting. This mistake might be the result of limescale buildup in the heat exchanger, a limitation in airflow, a broken output thermistor, or a problem with the thermistor in the heat exchanger itself.
  • Error code 24 – Switch failure, which might be caused by a damaged or malfunctioning control board or a faulty switch.
  • Error code 76 – Communication failure with a remote control, which may be caused by broken or missing connections on the remote control wire.
  • Error code 99 – Indicates that the blower motor is unable to vent owing to a clogged venting and exhaust flue, obstructed heat exchanger, blocked combustion, or blocked intake filter.

What Are The Steps I Need To Take To Reset My Tankless Water Heater?

The following is a step-by-step guide that will walk you through the process of resetting your Rheem water heater:

  1. Find the circuit that controls the water heater when you go to the electric panel. If it has been turned off, turn it back on.
  2. Take off the lid of the panel, and you’ll find the reset button hidden below the insulation.
  3. Apply inward pressure on it until you hear it click into place, and then let go.
  4. Change the cover of the panel.
  5. If the gas valve was turned off, you should turn it back on.
  6. The water heater has to be turned on and should function properly. In the event that there was an error code before the reset, it will be removed from the display if the problem has been fixed.

What Other Steps Should I Take If Resetting the Rheem Water Heater Does Not Correct the Problem?

It is possible that you may have to press the reset button anywhere from one to three times before the problem is resolved.

On the other hand, a single reset should be plenty to get your tank running again or get rid of any faults in the vast majority of situations.

In the event that the reset does not solve the problem, you will need to get it fixed by a qualified plumber or an expert in water tanks.

Remember that if there is an electrical failure, it may be lethal, particularly if you try to repair the heater yourself and water comes in contact with electricity or vice versa.

This is especially true if you try to fix the heater and are electrocuted.

For additional help, please get in touch with the Rheem customer support team.

The provider can even send a professional to your home or make a suggestion about how to fix the problem.

Also, examine the documentation that came with your Rheem water heater to determine whether you are qualified for any free work or replacement components under the warranty.

Where Is The Button To Reset The Rheem Hot Water Heater If It Has Been Tampered With?

The reset button on Rheem water heaters is often a red button that is positioned in the centre of the limit switch, close to where the thermostat is placed.

In order to have access to it, you will need to take off the metal panel that is attached to the device.

The insulator conceals the red button that must be pressed.

If it has been tripped, it will most likely be in the up position; to reset the device, you will need to press it inwards.

What Could Be Causing the Problem with My Rheem Tankless Water Heater?

The following is a list of the most frequent causes of your Rheem tankless water heater not functioning properly:

  • System overload
  • Expended fuses
  • The circuit breakers have been tripped.
  • pressed the button to reset.
  • An inaccurate thermostat as well as faulty thermistors
  • Vents and air intake pipelines that are obstructed
  • Accumulation of sediment and lime
  • Valves that are fully closed or partly open
  • No gas supply
  • Unsecured connections between the wires
  • Heating components that had been improperly wired
  • Switch for the high limit that does not operate properly
  • A few quick sips of hot water, etc.


It’s possible that the tankless water heater in your Rheem home has to be reset if it’s been overloaded, is displaying an error code, or the reset button keeps being tripped.

If the problem still occurs after you have performed the reset, you should get in contact with the water heater’s manufacturer or a qualified water heater technician.

How To Reset Rheem Tankless Water Heater Videos Suggestions From Youtube

How To Reset Your Tankless Water Heate – All Things Plumbing, Heating & Air
Hard reset Rheem tankless 99 error code – Cliff Palermo
Rheem Tankless Hot Water Tank | Troubleshooting – tkw1980ltd
Rheem Tankless water heaters troubleshooting – Guycho M Gruendler
Man Tips: Troubleshooting Rheem Tankless Hot Water Heater – Harley Armada

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Written by Bob Matsuoka
Bob Matsuoka is a blogger and founder of RVing Beginner blog. He has been blogging for over five years, writing about his own family’s RV adventures, tips for people who are interested in buying an RV or taking their family on an adventure by RV.