Navien NHB-150 water temp over 200 degrees

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Mev

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Got a call from my wife that the heating system was not working. The display on the boiler was garbled and flashing red. She turned the power off and on, and it seemed to reset, but the water tank is calling for heat and the display is showing 200 to 204 degrees and around 9psi. Also, she says there is no exhaust plume. It is in the 40s outside and there should be one. She felt all the pipes to the water tank and they are not warm. Maybe a bad circulator? I forgot to ask her if the light was on for that circulator.

The install plumber is on vacation and I was given another plumber's name to call. I can't get to the boiler until later this afternoon and she had to go to a doctors visit now so a plumber can't get to it until later if they have an opening.

I swear I did not change the default max boiler temp which should be 180.

Any ideas on what might be wrong without an error code being displayed?

Thanks,
Mark
 

WorthFlorida

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Since the displays are not reading right, I would say the control board is bad. Doubtful the water temp is 200 degrees.
 

Mev

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Got a call from my wife that the heating system was not working. The display on the boiler was garbled and flashing red. She turned the power off and on, and it seemed to reset, but the water tank is calling for heat and the display is showing 200 to 204 degrees and around 9psi. Also, she says there is no exhaust plume. It is in the 40s outside and there should be one. She felt all the pipes to the water tank and they are not warm. Maybe a bad circulator? I forgot to ask her if the light was on for that circulator.

The install plumber is on vacation and I was given another plumber's name to call. I can't get to the boiler until later this afternoon and she had to go to a doctors visit now so a plumber can't get to it until later if they have an opening.

I swear I did not change the default max boiler temp which should be 180.

Any ideas on what might be wrong without an error code being displayed?

Thanks,
Mark
Haven't heard back from the other plumber yet.
The wife called me again and there was a E001 error code. Had her turn the power off and was able to get home. Did an air purge, but got no bubbles after filling a 5gal bucket. Started trying different things (power cycling, disconnecting the indirect loop thermostat so the baseboards would get heat,..) but the boiler temp would climb fast.
The main circulator boiler pump (under the boiler), a Grundfos ups26-99fc, was cold and didn't seem to be running. I changed the speed of that pump from L to M, same problem. Changed the speed from M to H, and everything is working. Boiler temp increases to 180, burner shuts off, all 4 baseboard zones keep pumping, boiler temp decreases until the burner kicks in at around 150.
So, I shut everything off, changed the Grundfos back to L speed, and everything is still working.

The Grundfos pump is 3.5 years old.
Do I now just replace the Grundfos, keep a rubber hammer near by and wack it every once in awhile, or do nothing?
Thanks again for all comments, you don't know how much I appreciate it. I'll tackle anything electrical, but not plumbing.
 

WorthFlorida

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It could be the circulator motor is on the edge. If possible measure the voltage at the motor the next time should it happen.

Was the water very hot at 200* or just a bad reading?
 

Mev

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It could be the circulator motor is on the edge. If possible measure the voltage at the motor the next time should it happen.

Was the water very hot at 200* or just a bad reading?
All the pipes were cold to the touch. The 4 Taco zone circulators had an amber light constantly on, but those pipes were also cold.
I would guess it was a bad reading, but when I first got here, purged the system, and turned the boiler on, I could see the display temperature reading increase from from 65 to 175 within a minute or 2. I turned the system off at 175. So it looked like a correct internal temperature.
Complete guess: Without the Grundfos running, maybe the Taco zone pumps just recirculate the water within the zones without going thru the boiler? The main pipe under the boiler, there is a name for that thing that I can't remember, has a thru piece connecting the in and out pipes of the boiler. Maybe that is why none of the copper pipes were hot.
 

Mev

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It could be the circulator motor is on the edge. If possible measure the voltage at the motor the next time should it happen.

Was the water very hot at 200* or just a bad reading?
While working, there was 116v at the pump terminals
 

Mev

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Didn't throw a E271 code?
I did not see any codes after I came home and turned it back on. My wife first saw what she described as red gobbledygook flashing, and then seeing the E001 code before she turned things off.
 

Mev

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I did what an old plumber taught me. Took the metal end of a screwdriver and placed it against the Taco pump, the other end went into my ear. It sounded like a motor/gear moving smooth. I then did the same with the Grundfos, that has a consistent rattle noise, but that pump has been working on L for about 2 hours. I switched over to heating the hot water tank and it looks good.
 

Mev

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