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Navien NHB 110

bobby32xbobby32x Posts: 17Member

A few things. First, I am a hobbyist and have no real place messing with a whole house heating system, but I am also limited to the amount of money I can shell out for such things. So, I jumped into the rabbit hole and now I am at a loss.
A few weeks ago, I started having a lot of issues with my previous peerless purefire boiler. I opened the front of the burn chamber and found that it had sprung a leak on the heat exchanger coil. I had replaced the flame sensor (due to alarms, not due to the hole in the coil :neutral: )and this didn't help my cause. As you see in the subject of this, I am not here to repair that boiler. A coworker of mine told me to look into the Navien boilers, which I did. The price was reasonable and I jumped on it. I ordered up the boiler by way of figuring out my previous boiler output vs the one I settled on. I realize that is not the most efficient way to calculate my homes needs, but it was the way I went anyway. That said, my old system was rated at 89k BTUs, I went with the NHB 110 because it was 110,000 BTU's with a 11:1 turn down ratio. I figured over sizing with these capabilities should work, especially if something changes in my home that requires a larger demand.
The install went pretty flawlessly. I hooked everything up, purged my baseboard hot water of all the air and fired it up. On its maiden voyage, the boiler kicked off 3 to 4 times over the course of roughly an hour stating that the boiler overheated. I assumed that air must be trapped somewhere and I purged the system again. It has been heating my house for a few days now and on occasion, the boiler starts to sound like a hump back whale (Meeeeewwwww) only during the ramp up cycle. So, I started scouring the internet and came across a NHB boiler maintenance video on YouTube. I figured nothing I was interested in would be on it as it was probably a clean out for the boiler to help make the boiler last longer and I was right, however, somehow I missed the fact that the boiler has an inline screen on it and I even read the instructions tirelessly. So, I went down and pulled the screen and sure enough there was all kinds of crud in that screen. Little black, brown and red specs the size of the tip of a pencil or so was already in the screen. My previous boiler did not have a screen, so I imagine this was build up over the years. Note: my water is pretty hard. I haven't tested just how hard it is, but the water hardness has destroyed my dishwasher and more than likely put the old boiler through the paces. I intend to put in a water softener within the next few days.
After emptying the screen and replacing it, the noise seemed to go away. One thing that I noticed was that after cycling the power down via the power button held for a few seconds, doing the maintenance and powering the boiler back up, the boiler goes into limbo. I assumed turning it back on it would do its thing and we would be off to the races. Well.... It did something, but not what it was doing prior to the maintenance (and yes, I purged the system again to get the air gap out I had just made by emptying the boiler). It sort of slowly started to heat up. Now in hind sight, this could have been nothing more than the water returning to the system that was now hotter than the water that was in the boiler prior to turning it back on. I assume that this boiler, as most, have a freeze protection setup where once you turn it back on and it senses the outside temp, it begins moving the water to prevent freeze ups.
My wife began complaining that it was getting cold, which at this point confused me because I just had performed that maintenance and it seemed normal to me when I came back upstairs. I went down, unplugged the unit, waited a bit and plugged it back in and it all seemed fine
Fast forward to yesterday. I come home from work, house is warm and meeting the thermostats needs, I am happy. Then the wife says "Its staying warm in the house but it sounds like we have a hump back whale in the basement" sigh.... So I go down and perform the same maintenance as previously mentioned. There was more sediment. I need to point out that during this procedure, I am also toying with the water inlet valve. I figured that while purging the system of air, I should have the pressure a little higher to help convey the air through the system so I begin messing with the fill valve and I operate it between 13 and 30 psi and no more than that. The book says that this is a normal parameter for the boiler.
today the wife contacted me and said that the boiler isn't making the set point. I asked her to listen to it and see if it appears to be working correctly and she said "um.. I think... so...?!? the temperature on the display is 96 degrees and the pressure is at 16 psi. It sounds like it is heating up and the temperature on the display is going up but super slow." I told her that it should heat quickly and then she said "there it goes, it looks like it went up really fast, but now it is slowly trending downward and again, the house is 68 degrees with a set point of 70. It's hard to trouble shoot this thing with you guys while I am at work but I asked her to make sure it wasn't in a heat cycle and then unplug the boiler and wait a bit, plug it back in and see if that doesn't help. I assumed maybe I had potentially put it into a maintenance mode last night.
So, a few questions.
1, why the hump back whale noises?
2, does it sound like I put it into a maintenance mode?
3, does any of the above fall into a category that I am doing something wrong?
Thanks in advance, Bob


  • IronmanIronman Posts: 5,468Member
    How about posting some pics of the boiler and its near piping far enough back to include both?
    Bob Boan

    You can choose to do what you want, but you cannot choose the consequences.
  • bobby32xbobby32x Posts: 17Member
    I may be able to get some better pics. One is a panoramic and one is of the panel off the front. If more is needed, I will have to wait an hour and a half as I am at work

  • bobby32xbobby32x Posts: 17Member
    I had considered that the noise may be attributed to the circulator being on the inlet (return), but here is why I chose to install it there.
    1, it is in the suggested setups for this system (more than one setup)
    2, I know that at work, our dowtherm boiler runs under about 35 PSI. if we were to run it lower than that, the inlet of the pump would create enough suction (pressure loss) that the oil would actually boil and that kicks the boiler off, so I was applying a similar theory
    3, I read an article that talked about new age ideas vs old age and it pointed out that the circ pump can be installed on either side, return or supply and that it is up to the installer (pump toward, pull away discussion)
  • bobby32xbobby32x Posts: 17Member
    edited December 2019
    you don't suppose that my circulator is overpowering the boilers internal pump to make that noise do you? My circulator has 3 settings. amps?! 110, 80? and maybe 55 (eco)?
  • GroundUpGroundUp Posts: 815Member
    I don't suppose you bothered to read the manual when piping this in, or you'd have noticed it should be piped differently with a primary secondary setup and the boiler loop hydraulically decoupled from the heating loop. Secondly, has anyone investigated where the whale lives? I see no gas regulator in the photo so I'm wondering if perhaps the gas pressure is off and the whale is in the burner ( I have heard a similar sound with improper gas pressure). Or if it's coming from the pump, there may very well be either air or sediment lodged in the impeller causing similar sounds. 2 things are certain:

    1-you need to flush the entire system and get all that crud out of it, probably add some sort of mag filter

    2- the boiler needs to be changed to primary secondary piping
  • DZoroDZoro Posts: 1,020Member
    In your owners manual refer to page 30, 39, 98, 99 and quite frankly the entire manual.
    Can't see behind the pressure tank piping but it should look like that on page 30.
    Gas pressure and combustion analysis must also be done.
  • bobby32xbobby32x Posts: 17Member
    Ok so I will take the time to fully investigate what you are all suggesting, I just don't have a lot of time tonight for that just yet. I agree on the gas thing as I don't have a tester and that is pretty indicative of that noise and ultimately where the hump back whale lives. I do however have a regulator on the outlet of my tank and another on the side of my house where the gas comes in the house.
    Also, if you refer to the diagram on page 31, my system is pretty damn close to that one in my opinion. I have a boiler pump and a circulator switch to help direct flow to required zones (zone 1 or 2). I want to thank everyone for their mystical insight and apologize up front for being stupid. I am learning though, so it is appreciated.
  • IronmanIronman Posts: 5,468Member
    At least 3 things to note:
    1. The boiler does NOT have an internal circulator.
    2. It must be piped p/s using Navien's manifold or field fabricated closely spaced Tees.
    3. An external filter, such as a Caleffi DirtMag, must be installed.

    Bonus note: the system should have been thoroughly flushed before the valves to the boiler were opened.

    Here's a link to the manual which should have been followed: Installation & Operation Manual (English).pdf?sha=6a8aad478248d008

    And piping pics from the manual:

    Bob Boan

    You can choose to do what you want, but you cannot choose the consequences.
  • bobby32xbobby32x Posts: 17Member
    In the p/s loop described above, the boiler pump would control the loop that obviously goes through the boiler, but the 2nd circ pump looks downstream from the air scoop. will this pump run against the zone valves while they are closed or will wiring it to "pump 1" or "pump 2" location (boiler pump is wired to boiler location on the motherboard) on the boiler motherboard make it turn on only when a call for heat happens? I am just trying to get the concept down so I understand what I am doing here.
    My old system had 1 boiler pump that pumped the water into the boiler and out to the system which was fed to the main floor through zone valve 1, and upstairs through the zone 2 valve. Each zone valve is controlled by its own thermostat. I have parts on order to make the p/s loop nice and neat as well as a 2nd circ pump. The mag filter arrived yesterday. Once I get it all the parts, I will install and post a pic. Hopefully with your input here, I wont plumb it wrong and have to do it again. My gas supplier said they will come out and do a test on the system to make sure that is set correctly from the regulator. Though the whale has vacated my boiler :)
  • IronmanIronman Posts: 5,468Member
    Wire it to the "system circ" or "CH" terminals.
    Wire the boiler pump to the "boiler circ" terminals.
    Bob Boan

    You can choose to do what you want, but you cannot choose the consequences.
  • bobby32xbobby32x Posts: 17Member
    Last thing I think... can I plumb in the CH upstream from the air scoop or does it have to be downstream?
  • GroundUpGroundUp Posts: 815Member
    The pump? Should absolutely be downstream, especially if the expansion tank is connected to the scoop
  • bobby32xbobby32x Posts: 17Member
    Ok perfect. Thank you for the info
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