Navien NR-240A Gas pressure sensor replacement

[havasu]

My T/W/H is about two years old, and suddenly began receiving fault code # E 35, indicating irregular gas pressure. I called the tech. folks and they asked for me to confirm with a manometer that my pressure was perfect for the unit, and I determined it was. I again called the great folks at Navien, and they said it was most likely a faulty gas sensor. They asked for my address, and two days later I had a replacement sent to me via UPS.

This is a write up to show the steps necessary to replace this sensor.

Here is the tankless water heater in question.

 

[havasu]

Remove the 4 small screws in order to remove the cover.

 

[havasu]

This is the new sensor layed out with a few pieces of pipe, to correctly repair the incoming gas line.

 

[havasu]

Here is the bugger in question.

 

[havasu]

Remove the screw at the base of the unit, with the red arrow, in order to pivot the control panel out of the way. Since I failed to tell you previously, unplug the unit and shut down the gas for everyone's safety.

 

[havasu]

Using a long screwdriver and a long nose set of needle nose pliers, remove the two hoses from the sensor and unscrew the old sensor brackets.

 

[havasu]

Pull the old sensor and unplug the wiring which leads from the sensor to the control panel. You will need to snip off a few wire ties in order to completely remove the wiring.And yes, I received a boo-boo to my thumb in the process!

 

[havasu]

Feed the wires through the back of the control panel, making sure to follow the same path as when you removed the old wires. Screw in the new unit, making sure that the hoses are reconnected correctly, and zip tie the wires together to avoid burning and shorting the wires by accidentally touching the heated areas of the unit.

 

[havasu]

Replace the bottom screw to the control panel, and give one final inspection to make sure all hoses are connected and wires are all tucked in. Place the heater cover back on and screw back in the four screws to keep the cover in place. It also helps to blow any dust from the inside, wipe down and dirt or debris from inside, and give a final coat of wax to make the water heater look prettier!

That is it! Plug it back in, turn on the gas, and she should be good for a long time!

 

[LiQuId]

ahhh the pressure switch was the culprit... I wasnt sure exactlly what you were meaning by "sensor" these do foul on occasion.

 

[havasu]

The gas company said that is usually the first part to wear out. The company techs I spoke to didn't tell me how often this occurs, but I got the impression it does happen occasionally.

 

[LiQuId]

yeah, i've changed out a few on boilers this year, you can test them by blowing on the tube ( or sucking depending on the switch type ) and seeing if the boiler then fires.

 

[Scott Lyins]

ahhh the pressure switch was the culprit... I wasnt sure exactlly what you were meaning by "sensor" these do foul on occasion.

So where is the pressure switch located? You describe the pressure sensor but not the switch,,, thank you

 

[twinkle]

My T/W/H is about two years old, and suddenly began receiving fault code # E 35, indicating irregular gas pressure. I called the tech. folks and they asked for me to confirm with a manometer that my pressure was perfect for the unit, and I determined it was. I again called the great folks at Navien, and they said it was most likely a faulty gas sensor. They asked for my address, and two days later I had a replacement sent to me via UPS.

This is a write up to show the steps necessary to replace this sensor.

Here is the tankless water heater in question.

I have the same heater and get the same E35 error every few weeks. Is there a way to test that it is indeed the sensor and not something else before I order a new part? Thanks!

 

[havasu]

I really don't know whether the sensor could be tested prior to replacement, because I assume if Navien throws an error code, this part is needed. I guess you could pull it apart, blow it LIGHTLY with an air compressor, then replace. The worst thing that would happen is you would still throw this same code, and a new sensor would be needed?

 

[twinkle]

I'm sorry, but this was over 10 years ago, and can't be certain if the part corrected the situation, or combined with cleaning it.
Hell, I can't even tell you what I had for dinner last night!

Lol, thanks anyway. By cleaning, do you mean the sensor itself, or the hoses connected to it or something else?

 

[twinkle]

yeah, i've changed out a few on boilers this year, you can test them by blowing on the tube ( or sucking depending on the switch type ) and seeing if the boiler then fires.

Does this apply to tankless heaters too to test the gas pressure sensor?

 

[Twowaxhack]

Test your gas pressure with a manometer at the Navien.

 

[havasu]

Lol, thanks anyway. By cleaning, do you mean the sensor itself, or the hoses connected to it or something else?

I was referring to cleaning the interior of the unit itself.