Rinnai error code 10 indicates that the air supply or exhaust system is blocked or has some restrictions to disrupt normal airflow or flue gas extraction. The air pressure sensor measures the airflow.
This applies to all tankless water heaters from this manufacturer.
Models that are coming from the Sensei series, which includes RUR and RU models, would also display error code 10 if the condensate trap is full.
There are several reasons why code 10 occurs:
Tip: Before trying to repair or change any of the affected parts, try first to "restart" the unit by turning it ON and OFF. It could solve the problem. If it doesn't work, follow the troubleshooting steps below, or contact a professional plumber/technician.
Always buy Rinnai original components and what is recommended for your Rinnai model. Yes, there are many aftermarket parts available, but only the original components should be used.
Code 10 would show up if the wrong venting material is used, venting elements are not correctly connected, if it is incorrectly sized, or something is blocking normal air intake or exhaust.
Remove the exhaust pipe located at the top of the water heater and turn your Rinnai water heater ON. If the water heater is still coding out, then the problem is not with the venting system.
Disassemble all the connections, confirm there are no damages on the pipes (such as significant dents and changes in its diameter), remove all the dirt and debris, and re-assembly it again, following the manufacturer's instructions. As mentioned before, verify the right venting type is used, the number of elbows is not exceeded so as the maximum length, and recommendations for the proper clearances are followed.
Removing the vents is only temporarily – for testing. It must always be installed while working to direct the flue gases outdoors – safely and have an uninterrupted air intake.
For the normal operation of the vent system, inspect it at least once a year.
If the condensate trap is full and doesn't drain, the condensate line becomes clogged, causing you only problems. Blockage in the condensate line will trigger a diagnostic code 10, which will appear on the control panel display or a remote controller. The condensate line can become clogged due to the presence of dirt or if it freezes up, or the line gets damaged. Check the condensate collar if it is properly installed and is not loose.
To check the electric blower for proper work:
This applies to indoor models only. Make sure that the internal air filter is clear of debris, lint, and dirt. You can use dish soap and a soft brush to clean it. Try to inspect the air filter periodically and as specified by Rinnai. Once you remove the front panel, it is easy to locate the air filter at the unit's upper/right-hand corner.
Follow the instruction provided by the Rinnai manufacturer to remove the heat exchanger and gas burner assembly. Clean out the elements (heat exchanger, copper fins, gas burner, an orifice) from debris, dirt, carbon deposits, mineral build-up, and insects. There must be no blockage of any type so that nothing can cause airflow restrictions.
Ensure that high altitude parameter settings (DIP switch) are correctly chosen for your place, where your Rinnai tankless is installed. You can adjust the PC board parameters using one of four selections, where the maximum altitude is 10,200 ft.
Where it applies, the DIP switch should be in the right position for the chosen vent length.
Low and high fire pressures on the gas manifold should be set as specified by the manufacturer. If this is not adjusted accurately, the sensor won't be able to recognize the temperature change.
Important: Always hire a licensed professional to service or fix your Rinnai tankless water heater.
If you are planning to do it, always turn OFF gas, water, and electrical supply.
Rinnai tankless water heaters can show error code 10 for various reasons. As you can see from the above text, troubleshooting diagnostic code 10 in some instances is not complicated and doesn't require you to call a plumber.
You can do it by yourself. In other situations, where the repair requires advanced knowledge, experience, and special tools, you might want to contact a licensed technician.
Dealing with an innovative device and cutting-edge technology, as found in Rinnai, could lead to even more problems, void the warranty, or put you and your family in danger.