If you see an error code on your Rheem Tankless Water Heaters appliance, then the chance is you want to call a professional as soon as possible to help tackle the problem. However, sometimes, they can be resolved by yourself. Rheem provides its customers with digital displays and monitoring mobile apps for some models, so you’d be able to identify the issue and take the right steps to troubleshoot and find the solution.
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Below, you are provided with two examples of Rheem Tankless Water Heaters error codes along with the guide on how to put an end to the problem.

Rheem Tankless Water Heater Error Code 13
Error code 13 on Rheem Tankless Water Heaters means there are problems with a flame rod. There’s a possibility of improper or poor combustion. Here are several ways on how to solve this specific error problem:
- Check if the exhaust venting and air intake are installed correctly and working in good order. The exhaust should never recirculate into the clean air intake of your unit.
- Observe and get rid of any blockage within the venting.
- Check and confirm the location altitude settings.
- Inspect the blower motor and Flame Rod FL-24.
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Rheem Tankless Water Heater Error Code 29
If your unit displays error code 29, it means that the temperature of heat exchange is far too low. It also may indicate a clogging neutralizer inside the condensing unit. Perform the steps below to resolve this issue:
- Clean the heat exchanger’s fins
- Clean the screen of the air inlet
If the unit still displays error code 29 even after you have performed the cleaning actions above, then do these following inspections:
- Observe to see if the drain line is blocked and if you have removed the shipping cap.
- Check the unit’s inside part and clear ports of condensate drainage.
- Check the unit’s outside part and clear the line of condensate drainage.
Most of the troubles with your appliance can be solved by performing reset action. To do so, you have to press the Rheem tankless water heater reset button. As mentioned above, some models are also equipped with mobile app monitoring to install first on your phone. Otherwise, you may refer to the manual book of Rheem heater.
The components need to be shut off before you touch or open them. Touching the wiring or electrical elements while the unit is being turned on may result in electric shock.
It has to be noted that the steps to resolve Rheem Tankless Water Heaters error codes above are merely for informational purposes. Taking the issues by yourself might bring the risk of nullifying the applicable warranty. If you cannot recognize the error code even after referring to the manual guide or mobile app, then it is much recommended to consult a professional.
A professional or licensed plumber can help you run physical troubleshooting and diagnostic of the unit, regardless of the displayed Rheem Tankless Water Heaters error codes. Alternatively, you may reach the company’s technical support team by dialing 1-866-720-2076.