Rinnai Tankless Water Heater Code 10

Rinnai Tankless Water Heater Code 10 [How To Fix]

This is a complete troubleshooting guide on Rinnai Tankless Water Heater Code 10. What you will learn from this article is: 

  • 7 common reasons that can lead to the error code 10
  • Troubleshooting steps to solve those issues that are responsible for popping up the fault code 10

Without further ado, let’s dive in. 

Table of Contents

Rinnai Tankless Water Heater Code 10 [How To Fix]

Error code 10 on Rinnai Tankless Water Heater indicates the air supply and the exhaust gets clogged or the condensate trap is full. By releasing blockage from air supply and exhaust, you can easily clear the error message 10 from the display. 

Besides, other culprits like obstructions in the internal air filter, improper high altitude setting, clogged fan, and stuck check valve between fan casing and burner body are responsible for throwing the error code 10. 

Below, I will walk you through every troubleshooting step to fix those problems, which will help you erase the diagnostic code 10. So, keep scrolling. 

01. Condensate Line Gets Blocked

The condensate line of your Rinnai Tankless Water Heater allows the condensate formed by heater operation to drain. 

If this line gets clogged by dirt or debris, the condensate can’t flow through the system. As a result, your water heater will throw the faulty code 10. 

Besides, a full condensate trap can also be a culprit behind this water heater issue.

How To Fix: 

Inspect the condensate line and clean it if needed. Ensure condensate is flowing through the line and the end of the drain is open to the atmosphere. Don’t forget to drain the condensate if the condensate trap is full. In this case, use the bottom condensate drain port at the bottom of the unit.

Safety Tips: The condensate is acidic. So, ensure you drain it into the sewer system. Draining it outdoors may bring damage to plants or make the pathways slippy.   

02. Clogged Air Filter

If you have an indoor model of Rinnai Tankless Water Heater, the air filter is a definite component you must inspect for clog. The error code 10 will appear on the controller display if it gets restricted by lint or dust buildup.  

How To Fix: 

For proper water heater operation, the air filter should be free from dirt or lint buildup. Follow the below cleaning procedure to clean the Rinnai Tankless Water Heater air filter:

1. Turn off the water heater by pushing the ‘on/off’ button, which you can find at the right hand side of the controller. 

2. Remove the air filter from the unit. In this case, what you need to do is-

  • Use a flat head screwdriver to remove the screws that hold the front panel in place.
  • Pull out the front panel and locate the air filter, which can be found at the upper right-hand corner of the unit. 
  • Finally, pull out the ‘Filter Pull to clean’ tab to remove the air filter. 

3. Now, it’s time to clean the air filter. Apply a little amount of mild dish soap and use a soft bristle brush to scrub the air filter. Start scrubbing or brushing the air filter gently to suck away dirt and debris. Once you brush the air filter optimally, rinse the air filter with clean water. 

4. Use a lint-free towel to dry the air filter. 

5. Put the air filter back into its place and secure the front panel by tightening the nuts. 

6. Lastly, power on your tankless water heater. 

03. Improper High Altitude Setting

You should set the temperature of your water heater based on the high altitude installation location. If you fail to make proper temperature adjustment based on the right parameter setting, it will cause the error code 10. 

How To Fix: 

Take a look at the below screenshot and choose the proper high altitude setting. I hope it will help you if the error message 10 appears due to improper high-altitude setting. 

04. Blocked Combustion Air And Exhaust Vents

Sufficient air is needed to ignite the gas tankless water heater. Regarding this, combustion air vents should be free from dirt, debris, and snow. If these messes cause the combustion air vent to clog, air can’t flow to the combustion chamber. Consequently, your water heater will pop the error code 10. Similarly, a restricted exhaust vent will also cause the same issue. 

How To Fix: 

Inspect the vent system of your tankless water heater periodically. Ensure there is no dirt, debris, and snow in the vent system. If the vent gets clogged by dust, release the blockage from the venting line. I highly recommend you call a trained and certified professional to clean the vent system. 

05. Vent Length Is Not Within Limits

Proper vent length and venting connection is must if you want to operate your tankless water heater smoothly. If the vent length is not within limits or you install vent piping improperly, it will cause the diagnostic code 10. 

How To Fix: 

The total vent length will be 25 foot. I highly recommend you hire a qualified plumber to vent your water heater for proper combustion.  

06. Clogged Fan

Your Rinnai Tankless Water Heater will also trigger the error message 10 if the fan gets clogged by dirt, insects, and debris. Turns out, restricted fan wheel, housing, and air duct can cause the tankless unit to pop up the error message 10. 

How To Fix: 

Remove the fan motor and check the fan housing, wheel, and air duct for restriction. Don’t hesitate to clean these components if you notice any obstructions. You can use a bristle brush to suck away dirt and dust from these places. 

07. Heat Exchanger Or Its Fins Gets Dirty

Check the copper fins in the heat exchanger for debris buildup. If the fins get restricted, they will restrict the airflow, which can trigger the fault code 10. Turns out, a dirty burner and filthy heat exchanger can also cause this problem. 

How To Fix: 

Get an air compressor that can deliver up to 120 PSI of air to blow out dirt and debris from the burner and the heat exchanger fins. Keep in mind; you must wear the safety glasses and mask when blowing out the burner. If you are unable to clean the heat exchanger with compressed air, it will be better to replace the heat exchanger. 


What happens if you don’t flush your tankless water heater?

You must flush your tankless water heater once a year or every two year. If you don’t flush it, scale deposits will make their home in the unit. As a result, it will prevent your water heater from functioning properly. 

How long do Rinnai water heaters last?

You can expect the longevity of a Rinnai tankless water heater for up to 20 years if you take care of it according to the manual. 

What is the average cost to flush a tankless water heater?

On average, it will cost you up to $15o to flush a tankless water heater. 


I discussed all the possible reasons that cause the error code 11. Once you fix those issues, it will help you clear the error message. However, if the fault code returns after trying those troubleshooting steps I mentioned, call a certified plumber to fix this issue for you. 

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