Sunday, December 18, 2016

Navien tankless water heater: Error code 38

My Navien tankless water heater (model 240A) stopped working all the sudden. After opening the cover, I found code 38E displayed on the control board. However, this error code was not found in the operation manual.

According to Navien's FAQs:
"I have no error codes on my remote, yet my unit will not produce hot water. What should I do?

The issue is most likely the flow sensor inside the unit is not spinning properly.

We recommend opening and closing the pressure relief valve (should be located near the outlet of the unit). Depending on amount of debris affecting the flow sensor, this may help temporary. We recommend contacted your original installer or an NSS to service the sensor."

I also found this 38 error code listed here mentions checking the water flow sensor. Based on various forum discussions, it seems to be the root cause for others who experienced the same error as well.

Solution:
Luckily, it is not too difficult to take it apart and check the water flow sensor. Thanks to youtuber Tredsaw12 who created this step-by-step guide, I was able to extract the water flow sensor. If this is your first time working with the water heater, I would suggest you first check this video by Skobel Homes to get a better understanding of it.

After taking out the sensor, try shaking it. You should hear some noise as there's a small gear inside. If not, it's probably stuck which caused the failure. Check if there's any blockage inside and clean it. Try running water through it. Also try blowing air through it with your mouth. You should feel the gear inside is spinning.

And then, you just need to reverse the process and put it back together. Hopefully your water heater will start working again. If not, you may need to replace the water flow sensor and/or call a professional for further inspection. Good luck!

Update (2017-05-29):
It has been almost 6 months now. I would say the method above is a temporary solution. After cleaning the water flow sensor, the 38E error would come back after a few weeks. After 4-5 times, I decided to put an end to all this. I replaced it with a new sensor (you should look up the right model for your water heater). It has been going strong for months. No more 38E :)

Ref:
Navien Tankless Error Codes
FAQ | Navien
SIMPLE - Navien tankless FLOW SENSOR replacement -- 10 minute job - YouTube
How to maintain your tankless hot water heater - YouTube

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