How to Reset Rheem Tankless Water Heater

A well-maintained Rheem tankless water heater works properly for the most part. However, you may occasionally need to reset them if they become faulty.

Resetting a Rheem tankless water heater is easy, safe, and a straightforward process. First, ensure that the unit is powered on. Next, open the front panel to locate the red reset button near the thermostat. Press it down until it clicks in place. The unit should resume normal operation.

Below is a look at the various reasons you might need to reset your Rheem tankless water heater, the step-by-step instructions for resetting, and answers to related FAQs.

Why Do I Have to Keep Resetting My Tankless Water Heater?

Below are some possible reasons why you keep having to reset your Rheem tankless water heater.


Water heaters have specific hot water capacities. If your demand for hot water at a given point is higher than the unit can deliver, it will only supply cold water. Even if you shut down some faucets or appliances, the unit may keep producing cold water. The solution would be to reset it to factory or default settings.

The Reset Button Keeps Tripping

The reset button is a key safety feature in most water heaters. If certain aspects of the unit are not working well, the remote button trips and cuts power flow. This puts the unit’s operation at a halt, preventing further issues such as fire hazards when the heater is overheating.

To ascertain that the reset button has tripped, check the electrical panel. For example, locate the circuit labeled “water heater” and check if it is on or off. Usually, when the reset button trips, so does the circuit breaker. Consequently, the socket flips off.

The most common reasons for your Rheem water heater reset button tripping include:

  • Loose wiring connection
  • Short circuit in the heating element
  • Faulty reset button
  • Faulty high-switch limit

If There Is an Error Code Displayed

Sometimes, if a Rheem water heater is faulty, it will only display the relevant Rheem error code. Other times, it may reset the unit and power it off.

The most common Rheem water heater error codes that may cause the reset button to trip include:

  • Error code 00 – Continuous water heater
  • Error code 05 – Inadequate flow of air into the combustion chamber that may result from blocked vent exhaust
  • Error code 11 – Ignition failure that may be caused by partially opened or closed valves, excessive gas pressure and volume, open or short-circuited gas solenoid valve, a faulty igniter
  • Error code 12 – Flame Failure. This error indicates that the tankless unit has not detected a flame. The system faults for safety reasons and to prevent damage.
  • Error code 13 – This one is specific to indoor Rheem tankless units. It indicates improper combustion that may be caused by a defective flame rod or fan motor or limited air intake.
  • Error code 14 – Overheated film wrap that may be caused by airflow restriction to the combustion chambers, faulty heat exchanger, or foreign materials in the combustion chambers and exhaust pipes
  • Error code 15 – Indicates that the heat exchanger has been operating at a temperature of 207F or above for over 15 seconds. This may be caused by limescale build-up in the unit and obstructed cold water inlet pipe, faulty heat exchanger thermistor, partially open or closed water heaters inlet valve
  • Error code 16 – Indicates that the outlet water temperature is above the thermostat setting. This error may be caused by limescale build-up in the heat exchanger, airflow restriction, faulty outlet thermistor, or faulty heat exchanger thermistor
  • Error code 24 – Switch malfunction that may result from a broken or faulty control board or a faulty switch
  • Error code 76 – Communication fault with a remote control which may be caused by damaged or lost connections on the remote control wiring
  • Error code 99 – Indicates that the blower motor cannot vent due to a blocked venting and exhaust flue, blocked heat exchanger, blocked combustion, or blocked inlet filter.

How Do I Reset My Tankless Water Heater?

Below is a step-by-step process for resetting your Rheem water heater:

  1. Head to the electric panel and locate the water heater circuit. If it has flipped off, flip it on
  2. Remove the panel cover and locate the reset button behind the insulation
  3. Press it inwards until it clicks in place and then releases
  4. Replace the panel cover
  5. If the gas valve was disconnected, reconnect it
  1. The water heater should power on and operate correctly. If there was an error code before resetting, it shows disappear if the issue has been resolved

What Should I Do If Resetting my Rheem Water Heater Does Not Resolve the Issue?

Sometimes, you may need to hit the reset button up to three times for the issue to resolve. However, a single reset should be sufficient to get your tank working again or eliminate errors in most cases.

If the reset does not work, contact a professional plumber or a water tank specialists to have it repaired. Keep in mind in case there is an electrical fault, it can be fatal, especially if you attempt to repair the heater yourself and water gets in touch with electricity or vice versa.

Contact the Rheem customer service for further assistance. The company may even send a technician to your house or recommend a solution. Also, check your Rheem water heater warranty documents to see if you’re eligible for free labor or replacement parts.

Where Is the Reset Button on a Rheem Hot Water Heater?

On Rheem water heaters, the reset button is usually a red button located near the thermostat, at the middle of the limit switch. To access it, you will need to remove the metal panel on the unit. The red button is behind the insulation. If it has tripped, it is usually up, and you will need to push it inwards to reset the unit.

Why Is My Rheem Tankless Water Heater Not Working?

The most common reasons why your Rheem tankless water heater is not working include:

  • System overload
  • Blown fuses
  • Tripped circuit breakers
  • Tripped reset button
  • Faulty thermostat and thermistors
  • Blocked vents and air intake pipes
  • Sediment and lime build-up
  • Closed or partially on valves
  • No gas supply
  • Loose wire connections
  • Short-circuited heating elements
  • Malfunctioning high limit switch
  • Short hot water draws, etc.


Your Rheem tankless water heater may need to be reset if it is overloaded, has an error code displayed, or the reset button keeps tripping. If the issue persists even after resetting, get in touch with the manufacturer or a professional water heater specialist.

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