Navien make whistling noise and sends propane in exhauset

[mcbklyn]

Hi,
I am homeowner trying to troubleshoot a problem with my heater.
I have Navien NCB-240E installed 1 1/2 yrs ago (manufactured 2016) on propane.
I have 500gl outside propane tank with 2 regulators (on the tank and on the house).
A month ago after refill my Navien started to make short (1-3sec) whistling noise when it fires up on both domestic and heating loop.
I also detect propane smell coming from exhaust pipe outside when it fires up.
This wasn't happening before. It has been working fine since installation.

First, I called propane company suspecting that there is something with their regulators/gas pressure. They came in twice and claim that all is good on their side.
I called Navien trained plumber and he was with Navien cust.service on the phone for 3 hrs. He replaced pressure valve but this did not help. Navien told him the next step is to flash the system, which I don't want to do now.

I suspect that this has something to do with how gas is burned inside the unit. Not sure if it might be related to new gas (it started happening after refill). I though that maybe fresh air intake got clogged. I took off heater's front cover and see that boiler does not make high pitch noise or it's only split second long. It still sends propane smell outside during firing. So it must be something related to gas/air mixture.

Obviously plumber I hired and Navien support have no clue what the problem is so I wanted to ask community for help here before I make next move.

Thank you.

 

[Plumber69]

Sounds like gas pressure is too high

 

[Sponsor]

 

[Humberto]

Hi,
I am homeowner trying to troubleshoot a problem with my heater.
I have Navien NCB-240E installed 1 1/2 yrs ago (manufactured 2016) on propane.
I have 500gl outside propane tank with 2 regulators (on the tank and on the house).
A month ago after refill my Navien started to make short (1-3sec) whistling noise when it fires up on both domestic and heating loop.
I also detect propane smell coming from exhaust pipe outside when it fires up.
This wasn't happening before. It has been working fine since installation.

First, I called propane company suspecting that there is something with their regulators/gas pressure. They came in twice and claim that all is good on their side.
I called Navien trained plumber and he was with Navien cust.service on the phone for 3 hrs. He replaced pressure valve but this did not help. Navien told him the next step is to flash the system, which I don't want to do now.

I suspect that this has something to do with how gas is burned inside the unit. Not sure if it might be related to new gas (it started happening after refill). I though that maybe fresh air intake got clogged. I took off heater's front cover and see that boiler does not make high pitch noise or it's only split second long. It still sends propane smell outside during firing. So it must be something related to gas/air mixture.

Obviously plumber I hired and Navien support have no clue what the problem is so I wanted to ask community for help here before I make next move.

Thank you.

I also have the same unit and I'm having the same issues after my gas company (Porco) filled up the tanks last month

 

[Plumber69]

???

 

[Plumber69]

https://terrylove.com/forums/index.php?threads/navien-noise.74095/
????

 

[Humberto]

https://terrylove.com/forums/index.php?threads/navien-noise.74095/
????

yes sounds like the same noise

 

[Snug Harbor]

Was there ever resolution to this high pitched noise? Mine is the same noise as Plumber69 posted with the “???”

 

[Fitter30]

Lp is can be fickle. Gas pressure and air adjustment has to be correct are the burner will howl. Serviceman with flue gas analyzer would be a good idea.

 

[mcbklyn]

I had same problems twice already and it was dual venturi that goes bad. I am not sure why as my air supply and exhaust are at least 4 feet apart.
After replacing dual venturi problem goes away.