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Navien NHB150 woes

GarymGarym Posts: 10Member
edited December 2017 in Gas Heating
Hi all I am hoping you can help. I will try to keep this brief.

We converted our home from oil to high-efficiency gas in April 2016. We have four heating zones. Three of them are Hydro air zones and one small zone over the garage is baseboard. I have nest thermostats on all four zones. For completeness we also have the gas line connected to an outdoor heated swimming pool as well as a gas log insert in one of the fireplaces that has been there since before we moved in 4 1/2 years ago.

This is our second heating season with the new system. It’s a navien nub 150. Our house is 4000 sf.

Last season our issue was that the baseboard zone never reached desired temperature. It just can’t do it. It used to be able to do it when we had oil but now it will not reach above 62°. The system just constantly cycles. We did have them put a Mitsubishi mini split unit in that room at the time of heating conversion. We did this because we wanted air conditioning in there since it is over a garage and is swamp in the summer. So I could have heat if I wanted to. Last year was not a huge issue since we had a mild winter and I only realized this lack of hitting desired temperature late in the season. That is where the kids play so I am not in there all the time.But I try not to use the Mitsubishi for heat because I am afraid that during the cold winter’s we will burst pipes feeding the baseboard. I realize I can just remove these but I am determined to figure out what the hell is wrong with the system.

This year including today our heat has gone out four times of the last 10 days. The error message is always the same. E 003 indicating an ignitor failure. Apparentlythey have replaced this twice and they have replaced the control panel inside the boiler is well. I am not sure what they are going to do today. Of note today I was successful in manually resetting the unit. Is currently producing heat although I don’t know for how long. It is literally 0° outside so I’m hopeful we fix this system.

My question for the group is do you think this could potentially be an electrical problem that keeps shorting something out inside the boiler? I ask this because on one of the days where we did not have heat my electric oven also did not work. When they came and fixed the heat the oven worked again. However they do not appear to be on the same circuit so if there is a connection it must be magical!

We pay a ridiculous amount in heat. For the month of mid October to mid December in New England we just use 280 servings. We only keep the temperature at 68 Max and down to 62 at night. There are no draft anywhere. We have had a significant amount of insulation work done including around windows and in the basement and in the attic. I just don’t get it. We are paying more for natural gas with all of this insulation work then we did with Order. Neighbors with homes of similar size use a 3rd to 50 percent less than what I use And they haven’t had all of the insulation work done .And all of their zones apparently work!

Do you think that the zone with the baseboard is the issue? If the zone is constantly calling for heat and is never satisfied I realize that is obviously definitely not efficient. But why would it not work? It used to work when we had oil and all of the other zones work currently. Could it be the water set temperature? Without really make that big of a difference? Is the fact that the boiler keeps breaking down somehow indicative of why that one zone would not work? Any help would be appreciated.

Comments

  • DZoroDZoro Posts: 302Member
    Suggest having your techs contact Navien while they are there. There is some testing that can be done to the unit, and confirm combustion and gas pressure settings. Hopefully you have the outdoor reset control working on the boiler. If you do, then strongly suggest not turning back your thermostats. Maintain constant temps if possible. Let the odr to its job and save you the money without turn downs. Radiant likes slow and steady.
  • EBEBRATT-EdEBEBRATT-Ed Posts: 3,894Member
    Seriously doubt the skill of the technicians you have.

    Sounds like the boiler controls are not set up properly. If the baseboard heated on oil there is absolutely no reason it shouldn't heat now, choice of fuel make no difference to the baseboard.

    Can you post some pictures of the boiler and the piping around the boiler. Step back so we can see what is going on.

    The excessive gas use is also troubling

    Where are you located? Check out "find a contractor" on this site
  • SuzookSuzook Posts: 184Member
    ^^ I am sure the old oil boiler was putting out 160 degree SWT on that baseboard, and more than likely the new unit is much lower. Thats why they cant hit setpoint in that zone. I have the same issue in my upstairs zone. I need more radiation for lower supply temps. The OP probably does too. They could adjust the odr curve for hotter supply, and that should help.
  • IronmanIronman Posts: 4,201Member
    First of all, ditch the Nests. They real havoc with modulating equipment. Keep the stat set at one constant temp.

    Second, your boiler is severely over-sized which will cause short cycling. You BB zone is under-sized which will also cause short cycling. When the boiler short cycles off, it goes through a minimum time delay before it cycles back on. I'm not sure what it is one that boiler or if it can be adjusted. How many lineal feet of element are in the BB (not the enclosure length, but the element length)?

    The high limit setting for supply water temp may not be set high enough for the BB or the outdoor reset curve may not be set right.

    Mod/con boilers don't work well with a lot of zoning, especially micro zones like your BBs.

    Since your boiler is over-sized and you have a micro zone, the simplest solution is probably installing a properly sized buffer tank to get some mass back in your system. Your old boiler had high mass because it was cast iron. The new one is low mass and you have low mass radiation connected to it. You need to get some mass back in the system. This will cure the short cycling.

    Also, you need a COMPETENT tech who will setup the boiler controls properly.

    As far as the electrical, it sounds like you may be dropping a phase. That could be a bad main connection or bad main breaker in your service panel or in the service entrance or lateral.

    Your scenario is the classic case of an unknowledgeable, incompetent heating contractor thinking he can simply drop a mod/con in where a cast iron boiler was previously. He also made the mistake of over-sizing it because he probably used the size of the old one or he believes the misconception that bigger is better. Not so in boiler land!
    Bob Boan







    You can choose to do what you want, but you cannot choose the consequences.
  • GarymGarym Posts: 10Member
    Thank you all so much for your comments.

    UPDATE:
    Technician came today and noticed the ignitor was "slightly bent" which was causing it to ground out every once in a while when he was checking it. He "rebent" it and voila -- it's been working.

    Interestingly, a few days prior to the first time the system went out a few weeks ago, we had service. I questioned the efficiency, gas usage, etc. to the technician and he took a bunch of it apart to show me things. He was really nice and thorough but I wonder if he bent it during service. I had asked about this a while ago as a potential culprit (the guy, not the ignitor -- I'm not that smart)... and I was dismissed. Anyway, this still doesn't address the baseboard in the room over the garage.

    Oh and not sure if this matters but the water temperature is set to 180 for the main system and DHW. When it's heating for water, it gets to this temperature easily. But when it's on regular heat it never does. It usually hovers around 158/159. I asked the guy about this today and he wasn't sure. He checked all of the returns, one was a little cool so he drained some water to see if there was air in the line. It got hot again and that was the end of the visit.

    Doesn't make sense that it doesn't hit 180 degrees when it's 0 outside right? This is true even when ONLY the BB zone is on so I know it's not an issue of demand. Weird.

    EBEBRATT-ED: Gas consumption concerning in what way? It sucks but should I be worried re safety?

    Dennis: They've had Navien on the phone every. Single. Time. Not sure how helpful it was.

    Ironman: You hate NEST? For all zones? For what it's worth, we have all of them set to 68 during the day and 62 at night (I could not sleep in 68 degree temps). The BB room is set to 62. All the time. I'd love to set it higher but clearly that's not happening.

    You said the baseboard is undersized...did you get that form my first post? BTW the BB (fins) are 164". The room is 168x294", 7' ceilings , 2 dormers (it's over the garage). Photos attached.

    Oh we do have an expansion tank...is that what you're referring to?

    You mention the boiler is extremely oversized...what should it be and what size house should my boiler be in?

    Thanks again!








  • bob eckbob eck Posts: 716Member
    Turn all other zones thermostat down to 60 degrees so those zones will not call for heat.
    The room above the garage put that thermostat to 70 degrees.
    See if that zone by its self heats up to 70 degrees and turns off.

    Could the pumps on the heating zones be over pumping the system / boiler?
  • GarymGarym Posts: 10Member
    Bob eck I have done that very thing and the basebord never comes to the desired temperature. It would take several hours to move up 1°. I have run around the room and tried to fill every tiny little area that I felt was drafted to see if there was an issue. I just don’t get it
  • SuzookSuzook Posts: 184Member
    Call me crazy, but I see mostly pipe, and not much fin under the baseboard. How much fin do you have? I still think the temps for the baseboard are too low.
  • DZoroDZoro Posts: 302Member
    Glad to hear they have been in contact with Navien. May not always help, but it tells me that they probably set the proper gas/combustion settings on the boiler correctly. Nice pics, but there is one area that I can't quite see the piping and that is under the boiler. The size of that pump is that a up 26? And how that is piped to the boiler, it looks a little confusing/suspicious. Can't see how the domestic tank is plumbed into the system.
    Set back for a bedroom is understanding. Just don't expect fast recovery time.
  • SeymourCatesSeymourCates Posts: 162Member
    edited December 2017
    @Garym

    Can you confirm the "return absolute max temperature" is set to 158F? The boiler isn't going to climb to 180F unless the return is set to 158F and you can manage a 22F Delta between supply and return (difficult unless you throttle it).

    You have plenty of baseboard and plenty of boiler. Those are not the problem.
  • IronmanIronman Posts: 4,201Member
    > @SeymourCates said:
    > @Garym
    >
    > Can you confirm the "return absolute max temperature" is set to 158F? The boiler isn't going to climb to 180F unless the return is set to 158F and you can manage a 22F Delta between supply and return (difficult unless you throttle it).
    >
    > You have plenty of baseboard and plenty of boiler. Those are not the problem.

    13.6 ft of baseboard will output about 6300 btus at 170 average water temp and you don't see that as a problem being connected to a 150k btu mod/con?

    Please, don't make a misleading comment like that.
    Bob Boan







    You can choose to do what you want, but you cannot choose the consequences.
  • SeymourCatesSeymourCates Posts: 162Member
    edited December 2017
    @Ironman

    If you actually read the installation manual, what is interesting about the NHB-150 is that it has a minimum firing rate of 10K. So, all of your recommendations about the need for a buffer tank and the fact that the boiler is "severely oversized" are erroneous.

    But, that is completely irrelevant to the issue with the inability of the boiler to reach the programmed SWT.

    So, with all due respect, please confine your statements to the problem at hand.
  • EBEBRATT-EdEBEBRATT-Ed Posts: 3,894Member
    I agree with the room over the garage the baseboard will do 7000-8000 btu. You have a few windows and skylihts there. The problem over a garage is cold floors. You may not have enough baseboard.

    But you said the garage heated with the old oil fired boiler. That leads me to believe your water temperature with the new boiler is lower than the old boiler.

  • njtommynjtommy Posts: 1,096Member
    I know on the Navien combis there’s a dip switch setting that limits the return water temp to 149f max. That could be on.
  • IronmanIronman Posts: 4,201Member

    @Ironman

    If you actually read the installation manual, what is interesting about the NHB-150 is that it has a minimum firing rate of 10K. So, all of your recommendations about the need for a buffer tank and the fact that the boiler is "severely oversized" are erroneous.

    But, that is completely irrelevant to the issue with the inability of the boiler to reach the programmed SWT.

    So, with all due respect, please confine your statements to the problem at hand.

    First of all, how do you know whether I've read the manual or not?

    Second, you don't think that a boiler that's sized at 37.5 btus per sq. foot in a modern home that probably needs a lot less than 25 btus per sq. foot is over-sized? I've never seen the leakiest old farm house need more than 32 btus per sq. foot.

    Third, if the boiler is short cycling, then that's not irrelevant because it will cause it to not be able to keep up in a low mass system when it cycles off and goes through whatever anti-cycling delay that it has.

    Fourth, a zone that's less than 70% of the boiler's minimum firing rate does present an issue since modulation is to compensate for the heat loss of the structure, not improper sizing. If that zone is less than 70% of the minimum firing rate at design temp, it's less than 35% when it's 35* OAT.

    Fith, where do you get off instructing me how to comment? Did Erin Haskell appoint you vice moderator and not tell the rest of us?



    Bob Boan







    You can choose to do what you want, but you cannot choose the consequences.
  • SeymourCatesSeymourCates Posts: 162Member
    @Ironman

    First, the manual shows a minimum firing rate of 10K. If you read it, the entire argument of an oversized boiiler becomes moot. You do understand that this is a modulating piece of equipment, correct?

    Second, the boiler is not oversized with a 15:1 turndown.

    Third, the boiler is not short cycling with a 10K output even if the smallest zone requires 6300 BTUH. It may cycle, but it will most definitely not short cycle.

    Fourth, even in the situation where the baseboard demand is 35% of the firing rate, you manage that situation with the available timed start delay on the boiler. I'm quite sure you have installed CI boilers with 80K output. The building requires 10K on a 50F day and the system has no buffer tank and nobody cries foul about it. The boiler starts and stops. In this specific situation it will operate at a 30% duty cycle if no other zones call during the time the tiny baseboard zone calls. But here, since it is a mod-con, some demand that the smallest zone match the radiation. That makes not a whit of sense.

    Fifth, I understand that you don't like the truth in the subject at hand but insults are not going to change the facts.



  • IronmanIronman Posts: 4,201Member

    @Ironman

    First, the manual shows a minimum firing rate of 10K. If you read it, the entire argument of an oversized boiiler becomes moot. You do understand that this is a modulating piece of equipment, correct?

    Second, the boiler is not oversized with a 15:1 turndown.

    Third, the boiler is not short cycling with a 10K output even if the smallest zone requires 6300 BTUH. It may cycle, but it will most definitely not short cycle.

    Fourth, even in the situation where the baseboard demand is 35% of the firing rate, you manage that situation with the available timed start delay on the boiler. I'm quite sure you have installed CI boilers with 80K output. The building requires 10K on a 50F day and the system has no buffer tank and nobody cries foul about it. The boiler starts and stops. In this specific situation it will operate at a 30% duty cycle if no other zones call during the time the tiny baseboard zone calls. But here, since it is a mod-con, some demand that the smallest zone match the radiation. That makes not a whit of sense.

    Fifth, I understand that you don't like the truth in the subject at hand but insults are not going to change the facts.



    Since you want to correct and re-educate many of us here, why don't you share your vast experience with us?

    And about the only truth in your post is your own truth; it's certainly not factual.

    Bob Boan







    You can choose to do what you want, but you cannot choose the consequences.
  • GordyGordy Posts: 7,922Member
    Let's review deltas, and flow rates the issue may be there. Is that a grundfoss 2699 on the primary loop. If so please review the table with deltas verses flow rates for the nhb 150
  • DZoroDZoro Posts: 302Member
    Hard to see, but above the pump at the bottom of the boiler, is that a tee going to the domestic tank or does it go elsewhere?
  • GarymGarym Posts: 10Member
    Sorry for the delay and again I appreciate everyone's help.

    Gordy I'm a civilian. I honestly can't comment/respond. I appreciate your help but you might as well be speaking Greek unfortunately.

    When I view the basic information on the boiler this is how it's set:

    Space heating supply water temp (A. 156) isn't this supposed to be 180??

    Space heating return water temp (B. 142) Again not sure if this is what is ideal.

    DWH is set to 184.

    It's also running at 17.1 PSI if that matters.

    For completeness, it's 0 degrees F outside in Boston.

    Many thanks again!

  • GordyGordy Posts: 7,922Member
    Have you tried raising the supply. and return temps?
  • GarymGarym Posts: 10Member
    No. I only realized what it was set to an hour or so ago when I was downstairs. When the plumber has come to service the boiler once out, I was told that it was set to 180. So honestly I didn't check.

    You think it's kosher to change it? I don't want to screw anything up. What temps do you recommend?
  • GarymGarym Posts: 10Member
    edited January 8
    Actually I am unable to change it. I see that the outdoor reset mode is active and I suppose that is preventing me from adjusting it. I hit ‘mode’ but + and - just don’t adjust it at all.

    ALSO: it's 0 degrees here but the outdoor reset is reading the outdoor temperature at 34 degrees. It hasn't been above freezing for literally 2+ weeks. So obviously something isn't working.

    Also (and again I'm not a plumber and am new to all this) I just discovered the location of the outdoor temperature sensor a few days ago before it snowed. It's about a foot off the ground (oddly enough, where our old water meter/sensor was -- and they looked similar interestingly enough -- I'm guessing they moved the water meter/sensor. Again just noticed it since they really look the same from a distance). Clearly labeled NAVIEN and now it's buried beneath 2 feet of snow. I assume this placement isn't ideal either.

    Alas I'll bypass the O/R -- if I set to 180 supply, should I have it set to 160 return?
  • Paul48Paul48 Posts: 4,492Member
    Have you read the manual?
  • GarymGarym Posts: 10Member
    edited January 8
    Paul48 in depth and have it memorized? Of course I've looked at it. I don't get your question.
  • GordyGordy Posts: 7,922Member
    Depends on the reset curves setting.
  • GordyGordy Posts: 7,922Member
    Is the odr sensor properly placed as to not interfere with actual ambient readings? Sun, heat source. Should be on north side of house.

    I see the lowest on the low temperature for the reset curve range is -9. Default is 14. Is it in default setting?
  • GordyGordy Posts: 7,922Member
    From your supply temps on the chart it looks about like the low is set to default 14
  • Paul48Paul48 Posts: 4,492Member
    @Garym
    The question was not meant as a slap. Many people don't realize that they can sometimes answer their own questions by reading the manual. At the very least, you can at least be on the same page as someone that is answer questions for you.
  • GarymGarym Posts: 10Member
    Yes it was set to the default of 14. Should this be adjusted? I disabled the outdoor reset control to see what would happen. We shall see . Virtually everything was set to default.The outdoor reset heat load type was set to Finned tube baseboard. Not sure if it matters but the system supply water temperature and the return water temperature are both at 32. Just something I noticed not sure if it matters.
  • GordyGordy Posts: 7,922Member
    Well IF the ODR is/was hooked up the low temp default of 14 would have been an issue if the temps dipped below 14. Your supply water temp would have maxed out at what you needed for a low temp of 14 degrees. Look at the outdoor reset set up in the manual look at the chart.
  • GarymGarym Posts: 10Member
    So you’re questioning whether or not it’s hooked up at all too?
  • GordyGordy Posts: 7,922Member
    edited January 8
    Setup. If it’s default then 14 degrees is the default low temp. 70 is default high temp.


    Sensor. If not placed in an area that can be influenced by heat sources it will not read right temperature. Usually read warmer then actual outdoor air temp.
  • GarymGarym Posts: 10Member
    Thank you.

    Regardless just let me know it’s safe to leave the Odr bypassed for now?
  • GordyGordy Posts: 7,922Member
    You can disable the ODR in the menu. It then reverts to the users manually set supply, and return temps. According to manual return is max 147, and supply is 180 max. Setting manually in the menu.

    Can you confirm all dip switches are set properly? Using the I/O manual?
  • GordyGordy Posts: 7,922Member
    Reverting back to some of your posts it appears you confirmed the location of the outdoor sensor, and the fact it’s not reading the correct temp.

    1’ off the ground is not a good location for obvious reasons. Being buried in the snow. As to why it’s not reading the proper temp could be bad sensor which a resistance test would confirm. Could be heat source influencing the sensor. Sounds like a convienient spot for the installer.
  • tlwolfetlwolfe Posts: 1Member
    I'm late to this post, but I have a setup that is almost the same. I installed a Navien NHB150 in my garage last fall. One of the three heat zones in the upstairs of the garage. When that zone called for heat the NHB would short cycle. I viewed the service in formation J (Heat capacity) and noticed it was only going down to 15%. I found that parameter 3 (Space heating min capacity %) was set to 15% from the factory. It should have been set to 7% for the NHB150 with its 15:1 turn down. After making this change the system worked perfectly. I have 24 feet of baseboard above the garage, and I have found that the NHB runs at it min, or service information J now goes down to 7% and holds. If I had less than 24ft of baseboard I'd expect the NHB to short cycle.

    I am using the outdoor reset. The lower level of the garage has radient heat in the floor. I felt the reset curve for baseboard would be overkill for my radient, and the reset curve for the radient would be too low for my baseboard. I selected the fan coil curve which is hotter than high mass radient and lower than baseboard.

    My square footage is about the same as yours and I have 24ft of baseboard. My room heats up at around 5 degrees per hour when it real cold out. If I read correctly and you only have only 13.5ft of baseboard, I'd expect your NHB to short cycle, and I'd expect it to take along time to get the room up to temp, if it ever does get there. Based upon what I've learned from my setup, you need double the baseboard.
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