Rinnai tankless water heaters are the most advanced product in North America. They are of quality materials, are durable, have advanced features for a tankless heater, and have sensitive elements. However, much like most appliances, they may provide error codes. The best thing about this product is that it has a temperature controller that allows homeowners to control hot water and view error codes.
When an error code is present, a safety feature turns off the unit. You can use a self-diagnostic tool to inspect how the unit is operating. If it detects a problem, it issues an error code on these models: MCC-91, MC-91, and MC-502. It will flash at the clock display on the BC-100 and MC-100 units. There are more than 25 error codes in all, and they require a great deal of skill and knowledge to repair as they have a very complex design.
How Do You Read a Rinnai Error Code?
To find the error code, check the temperature controller. Press and hold down the on/off button for two seconds. Then press the arrow up and the previous nine error codes will flash and appear one after the other.
Error Code 02- Water heater burner isn’t functioning in freeze protection mode
Call a technician. Only they can fix the problem.
Error Code 03- (BC-100) Power Outage
This error code happens because the temperature controller is used for a bath fill function. No water will flow after a power outage has been resolved, so this error will remain on the controller.
The solution is to turn off the water flow for the hot water tap. Press on/off twice.
Error Code 05- Bypass Servo
To fix, turn the power off, then back on. Fire up the water heater. If the error code is still present, the bypass valve needs replacing.
Error Code 10- Reduced/No Air Supply to Water Heater or Obstruction in Flue Gases Out
Ensure the proper Rinnai venting is used and there isn’t anything obstructing the venting system. There should not be a reduction in the diameter and length of the vents.
Make sure there isn’t anything blocking the vents or fan. Properly set the dip/condensation collars and meet all clearances.
Error Code 11- No Ignition on Gas Burner
Rinnai tankless water heaters have an electronic ignition. Automatically, it assumes that there is no air found in the gas line, the grounding is correct, and there are no issues with the gas supply.
Check that the igniter generates a spark and the wiring connections are fine. Look at the gas burner to make sure it is installed correctly. Remove all dirt and debris if there is any. Inspect the gas solenoid valve in case there is a short circuit.
Error Code 12- Flame Failure
Find out if there is any loose wiring on the flame rod, PC board, and power supply. See if there is anything that is short-circuiting in the gas solenoid valve and reconnect wiring connections. Check to see if the venting system is blocked, the gasses vent correctly, and the combustion chamber gets adequate fresh air.
Error Code 14 & 16- Thermal Fuse Reacting to Excessive Temperature
If anything is blocking the water flow system or vent system, clear it out. If inadequate cold water is coming through the heat exchanger, this will cause the temperature to drastically increase.
Check to see if there is anything in the combustion chamber or scale build-up located in the heat exchanger. The heat exchanger should be in a solid-state. There should be no breaks or tears.
Error Code 19- Electrical Grounding
Check all components of the tankless water heater for an electric short.
Error Code 25- Full Condensate Trap
Solutions for this issue include unblocking the drain line, tank, and condensate trap. You can tighten or fix the sensor wiring harness or replace the condensate tank that contains the sensor.
Error Code 30 & FE- Flammable Vapors Detected
Leave the area until it is safe. Confirm the sensor is not damaged or if there are loose, broken, or damaged connections. Once you are sure the area is safe, turn on the power and gas. Then open a hot water tap to turn the unit back on.
Error Code 31- Buner Sensor Error
Only replace the sensor if it indeed is faulty or the resistance value.
Error Code 32- Faulty Temperature Sensor Located in Outgoing Water Line
You may have a loose connection or damage to the sensor wiring. Therefore, you should measure the resistance, or you can clean scale build-up. If it doesn’t clear up the issue, the sensor may require replacing.
Error Code 33- Heat Exchanger Sensor is Faulty
Before replacing this part, see if there is a loose connection. Then examine the incorrect resistance or clean the build-up of scale in the sensor.
Error Code 34- Combustion Air Sensor Faulty
Ensure the fan is working. Measure resistance in the sensor, then clean any scale, fix damaged wiring or loose connections, and remove any blockages restricting airflow. If this doesn’t fix the problem, replace the sensor.
Error Code 41 & 51- Freeze Protection Sensor Located in External Unit Not Functioning
Repair the broken, damaged, or loose sensor wiring harness. Get rid of any obstructions. If this still doesn’t give a proper sensor reading, then you may have to replace it.
Error Code 52- Issue with Solenoid Valve
Fix damaged or loose wiring/connections. Measure the valve coil’s resistance.
Error Code 57- Malfunction with Burner Overheat Bi-Metal Switch
The heater should have the correct pressure and fuel type programmed into it. If there was a conversion, it should have been done as per the manufacturer’s instructions. Examine the switch wiring harness. Make sure it is in the correct condition for operation. The sensor may be faulty and require replacing.
Error Code 58- Condensing Heat Exchange Sensor
Examine the wiring harness for damage, broken or loose connections. See if there is scale build-up in the heat exchanger. If there is, do a flush. Take necessary steps to reduce hard water to preserve the life of the tank.
Error Code 61- Fan Failure
Measure the fan motor’s resistance. See if there are any loose or damaged wiring or connections. Examine the fan to see if it spins freely or stutters.
Error Code 65- Issue with Water Flow Control Valve
Call a technician to fix it. This code is related to the bath fill function on the hot water tank.
Error Code 70- PC Board Fault
Examine the wiring. See that all dip switches are in their proper place. If needed, replace the electronic board.
Error Code 71- Issue with Solenoid Valve
Problem with an electronic board and it will need to be replaced.
Error Code 72- Flame Sensor Not Working
Check the sensor to see if it can contact the fire. Look for damage to wiring and loose connections. Use sandpaper to clean deposits found on the flame rod. Replace it if the above steps do not rectify the problem.
Error Code 73 & 79- Issue with Burner Sensor
Check to see if there is any damage to the electronic board or sensor wiring. Replace if needed.
Error Code LC or OO- Scale Build-Up in Heat Exchanger
If this error code appears, you may have to clean deposits left behind by flushing the heat exchanger. It may also need replacing. This code is the only one on a Rinnai tankless water heater that will still allow the unit to keep running.
How Do I Reset My Rinnai Heater?
Press and hold the connect button located on your unit. Keep holding until the LED is blinking white. Then, release it to restore the unit to the factory setting.
There are several error codes that a Rinnai tankless water heater can provide. Most of it involves checking the wiring, venting systems, maintenance, and checking for any obstructions.
As with most appliances, expect repairs for some of the sensors and elements after some time has elapsed. Make sure you conduct regular maintenance inspections, and your hot water tank will remain in good shape.