Intake/Exhaust piping issue with Navien NHB-150

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Mev

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The original installer piped the intake and exhaust from my Navien NHB-150 incorrectly according to a new plumber we called out for maintenance. The town inspected and OK'd the installation. I've attached a picture of the outside piping. The intake comes out of the house on the right of the picture, turns up, and then turns out. The exhaust comes out of the house at the same level, turns up but goes vertically higher than the intake (about 3" higher), turns out but sticks out more than the intake by about 9".
We will get this fixed: change over to 636 cpvc piping (new MA code) and separate the exhaust and intake ports further.
My question is:
From the new plumber: "the boiler pulls in already burnt fuel ( carbon dioxide ) to be used as fresh combustion air , there isn’t enough oxygen in the intake to burn clean and efficiently , can also cause misfires, the outside of the home has a white smegma on it that’s very difficult to clean, the ignitor is very red (knew there was a combustion issue before looking outside) this can cause premature failure of certain components and currently is via photos the top of the heat exchanger where it meets exhaust collar has a small leak"
Are those statements accurate? The reason I ask because there is other work this plumber is proposing that has added up to over $2k.
Thanks
 

Mev

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The original installer piped the intake and exhaust from my Navien NHB-150 incorrectly according to a new plumber we called out for maintenance. The town inspected and OK'd the installation. I've attached a picture of the outside piping. The intake comes out of the house on the right of the picture, turns up, and then turns out. The exhaust comes out of the house at the same level, turns up but goes vertically higher than the intake (about 3" higher), turns out but sticks out more than the intake by about 9".
We will get this fixed: change over to 636 cpvc piping (new MA code) and separate the exhaust and intake ports further.
My question is:
From the new plumber: "the boiler pulls in already burnt fuel ( carbon dioxide ) to be used as fresh combustion air , there isn’t enough oxygen in the intake to burn clean and efficiently , can also cause misfires, the outside of the home has a white smegma on it that’s very difficult to clean, the ignitor is very red (knew there was a combustion issue before looking outside) this can cause premature failure of certain components and currently is via photos the top of the heat exchanger where it meets exhaust collar has a small leak"
Are those statements accurate? The reason I ask because there is other work this plumber is proposing that has added up to over $2k.
Thanks
Forgot the picture
 

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John Gayewski

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They should be separated by 12" in height. The warm exhaust should have room to float up while the cold combustion air should slide in below that.

As long as the sizing is right you should be able to get away with changing the outside piping only.

It's correct that pvc is the wrong piping for this application, but it's also true that it will work for a very long time. I think your plumber probably knows your local regulations better than I, but changing all of the piping isn't necessary to achieve proper function, just the outside terminations need changed.

I don't see and smegma.
 

Mev

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I don't see and smegma.
There was a weird white coating on the bathroom window about 5' above the exhaust and on a first floor window about 15' away horizontally.I've tried a bunch of window cleaners and chemicals and it does not remove it. I can get some off using a single sided razor blade, but even that is very labor intensive. I've never seen something like that before. OK, I just looked up the definition of smegma, not really what I would have used to describe the whitish film on the windows.

Thanks for your other comments. Could the current placement cause the degradation of the igniter?
 

John Gayewski

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It could yes. But I don't know that it's the cause for sure.

Roof terminations are best. Is your gonna redo the piping maybe try to find a route to the roof.
 

Fitter30

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Was the burner set up with a flue analyzer? I'd put a 90° ell on the intake run 24" and call it good
 
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Fitter30

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That white coating is a product of combustion. A plumber won't have a flue analyzer. Boiler company will.
All the numbers they will need are in this manual.
 
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