How to troubleshoot Rheem tankless water heaters by using the service error codes chart. Symptoms, causes, and step-by-step troubleshooting guide to fix the most common problems on Rheem on-demand models.
Every Rheem tankless water heater, either non-condensing or condensing, utilizes the computer board to monitor the heating process, adjust the parameters, and help troubleshoot the potential problems.
The diagnostics become simpler since the Rheem tankless heaters use the electronic control board and advanced technology with an optional remote controller and control panel.
When the problem occurs, the error code is displayed on the LCD screen of the remote or user interface, so by understanding the meaning of the code, the troubleshooting gets easier.
We will assume that the licensed plumber/installer professionally installed your Rheem tankless water heater. When an error code is displayed on the screen and before you call the service support, do the following to reset the system, which might fix the issue:
If nothing happens after resetting the unit and the error code is still visible, do the following:
Cause: Limescale deposits in the heat exchanger... water flow is reduced, and the temperature increases significantly.
Solution: You must descale the water heater. See an example how to descale a Bosch tankless heater.
Cause: The blockage in the air supply pipe, exhaust vent, or connection/termination is loose or not correctly done. The alarm sounds every 60 seconds when the tap is open.
Solution: If you cannot find the problem in the venting system, and cannot remove what is blocking the regular operation, call the service.
Cause: The gas shutoff valve is not open completely.
Solution: Make sure that the gas shutoff valve provides enough gas to the main gas burner, and there is no obstacle.
Cause: The water heater and its burner doesn't get enough gas.
Solution: If your tankless water heater is using natural gas, make sure that there is no interruption in gas supply from the distributor. If using propane gas, make sure that the propane tank has enough gas.
Call the service if none of the steps taken above works.
Call the technician because the water heater is overheating.
Cause: Most of the time, the water heater doesn't start because the hot water tap is not fully open, so the water flow is low. Another problem that might occur when the water flow is reduced is the excessive temperature of the heat exchanger.
Solution: Make sure that the hot water tap is open enough to provide at least the minimum required water flow.
Clogged condensate neutralizer. Call the technician.
Change the faulty inlet thermistor.
Change the faulty outlet thermistor.
Change the broken blower motor.
An issue with the water flow solenoid.
The neutralizer needs to be replaced soon.
The neutralizer must be replaced.
Water flow is below the minimum required. Increase the flow.
The water shutoff valve and hot water tap need to be fully open. Increase the temperature on the remote if it is set too low. If the water heater has the mixing valve installed and does not operate properly, it must be replaced. Check if the water inlet filter or fixture aerator is clogged and unblock it if it is. Follow the descaling procedure to remove the scale build-up in the heat exchanger (there should be an error code).
Check the thermostat on the remote control; it might be set too low. Check the gas pressure; it might be too low, or the gas valve is not fully open.
The water temperature on the remote control is set too high. Water flow is too low, or the shutoff valve is not fully open.
The above list of Rheem tankless error codes might help you troubleshoot the problem successfully, but if you cannot solve it, you cannot find the code here, or it is hard to fix the unit, I would recommend calling a professional.
If you are calling the manufacturer, make sure to have the following info ready: