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Navien ch 240

RMARMA Member Posts: 55
any comments on the NAVIEN CH 240 ASME?

just installed one seems pretty nice.



  • kcoppkcopp Member Posts: 2,773
    do a search....

    for the site. Lots of comments. some ok, some not so much.
  • IronmanIronman Member Posts: 3,541

    Has pulled the CH line and is replacing it with another model that won't be available til next year. I don't know why or how you managed to still get one.

    The one major caution is to be aware that the on board pump is only 5 gpm and with most existing American systems designed for a 20* delta T that means you're only gonna get 50k btu's for space heating regardless of the burner input.

    We've installed a few with no issues, but I understand its limitations, too.
    Bob Boan

    You can choose to do what you want, but you cannot choose the consequences.
  • HDEHDE Member Posts: 142
    edited November 2013
    The replacement model is the NCB and it's available now

    Bob, it appears you don't fully understand injection with primary/secondary.

    Even if the secondary boiler pump is 5 GPM, that doesn't limit the system primary flow and BTU's

    Note the Viessmann 130,000 BTU is limited to 6 GPM boiler flow as another example.

    And the CH doesn't fire on a 20 DT, the new one is also adjustable.
  • IronmanIronman Member Posts: 3,541
    I understand ...

    The universal hydronics formula which you keep trying to rewrite. I also understand that what goes into a Tee, must come out of that Tee.

    If 5gpm goes into a Tee @ 180* and the radiation extracts 20* and returns it through the other Tee, that's 50k btu's no matter what math you try to use. It's not about a setting on a boiler or a fancy manifold which equates to no more than two Tees. It's about the system that's connected which seems to be something that you don't grasp.

    You state that I don't fully understand injection with pri/sec. That's a little odd to me seeing that I design, install and service these type of systems only continual basis. I've been doing this for over forty years from large commercial down to residential. And, I have the benefit(?) of servicing not only what I've installed but what others have also. So, I get to see the end results of what I've designed as well what others have. I've also benefited by what I've gleaned from others much more knowledgeable than myself have passed on, not the least of whom is the owner of this site. They all agree that the universal hydronics formula is etched in stone as an undeniable fact. But you seem to have come to a different conclusion.

    I'm teachable. Please enlighten me how what we've all thought and proven to be fact (btu's = (gpm x 500) x delta T) is now no longer true. Please show how Gil Carson was wrong when he taught that "What goes into a Tee, must come out of that Tee". Please show how your boiler with its magical manifold puts out more btu's than what went into it.

    Just so you know: I have taken thorough and accurate readings on jobs where we've installed CH 240s and used the above formula to confirm exactly what I stated: 5 gpm @ a 20* delta T = 50k btu's. I've also done it with a 30* delta T and the formula works.

    You appear to have very extensive product knowledge, but do you have any real experience as a technician in the field?
    Bob Boan

    You can choose to do what you want, but you cannot choose the consequences.
  • ChrisChris Member Posts: 3,056
    edited November 2013
    Its not Btu/hr

    That is the concern, its system supply water temp when your system side flow rate is larger then the boiler flow rate. A btu doesn't care about 180 or 120 degree water its still a btu. Using HD's 120K example on a typical 20 delta (which never happens in reality).

    (5 X180) + (7 X 160) = 12x

    900 + 1120 = 2,020 / 12 = 168

    Will 168 degree water get the job done and are we happy with an 8 degree system side delta? Iron by the way, the boiler is a tee, what goes in must come out no different then your closely spaced tees.. If I get 5 from the boiler, 5 goes back in. The 7 are what's left from the 12 in system side return after 5 went back to the boiler return.

    The difference between Navien and everyone else from an operation standpoint is that it does not recapture flue gas condensate, thus not picking up loss latent heat from the flue.
    "The bitter taste of a poor installation remains much longer than the sweet taste of the lowest price."
  • HDEHDE Member Posts: 142
    edited December 2013
    Good math but need to adjust for boiler perimeters

    Btw chris I disagree about the condensate capturing of latent heat. That's the purpose of the down firing with the collector at the rear to reroute flue captured condensate to saturate the secondary heat exchanger.

    For example similar in design to the tankless, they would not hit the 98% thermal- .97 & .98 EF the tankless is certified at.

    What's left out of the equation above is the boilers actual fire rate and it's delta t. If fire rate is higher or set to overshoot set point higher, more heat (BTU) is transferred.

    Anyways the AHRI certified ratings speak for themselves, it's not limited to 50,000 BTU's.
  • HomeOwner1HomeOwner1 Member Posts: 134
    It works fine

    I own one.

    The large BTU capacity is to meet hot water side demands for about two to three showers at the same time before losing some pressure.

    The heating side heats my large home just fine.

    It is efficient.

    Just took a look at their website. It appears the newer model has an updated burner that accepts a 1/2 gas line, rather than 3/4. Also, the vent pipe appears smaller. It also has higher overall combined efficiency ratings. The hot water side in a combi will drag the overall combined efficiency rating down.

    It puts out more than 50KBTU when installed properly to primary and secondary loops. The previous poster was incorrect, as it is proven by real life operations in my home.
  • ChrisChris Member Posts: 3,056
    Boiler Parameters?

    Not sure what you mean. My posting was really referring to the secondary side not the boiler/primary side and was at design conditions. Maybe I should have been clearer on that.

    I'm surprised with the new unit they haven't incorporated a system side supply sensor to assist in overcoming the water temp drop that happens on the secondary/ system supply when piped with either their manifold kit, two closely spaced tees or a low loss header. In reality it doesn't matter what the boiler supply water temp is, it's the secondary side that needs to deliver to the emitter an x water temp not the boiler.

    Homeowner, if you were referring to my post you are mistaken. I'm absolutely correct. Boiler only makes about 5gpm and if I need 12gpm on the system side the 7 has to come from the system side return. There are no Criss Angel's in the boiler room. Notice I didn't say anything about btu/hr and I didn't say you couldn't get more then 50K Btu/hr out into the system side. What I said was at what water temperature and that is critical.
    "The bitter taste of a poor installation remains much longer than the sweet taste of the lowest price."
  • TonySTonyS Member Posts: 849
    Just got a call this morning

    On one I put in a little over a year ago. Customer said it was working but making a noise.

    Raised the stats and sure enough, when the unit hit high fire it was making a screeching noise, almost like a bearing getting ready to seize. When it kicked down to a lower firing rate the noise disappeared.

    Called Navien and they were very helpful, we ran the entire gauntlet of test and procedures but to no avail, turning this thing on high fire produced this sound.

    After about an hour maybe two, Navien gave me a number for a new unit.

    No labor included, Im going to have to eat this one.It should be a fairly simple exchange though.

    Have any of you had this problem?
  • jonny88jonny88 Member Posts: 1,139
    gas pressure

    did you check gas pressure,minimum 7" wc,full port ball valve on gas line etc.I had a call last week and that was the problem but if your getting a new unit im sure all that has been checked,good luck
  • Robert O'BrienRobert O'Brien Member Posts: 2,938
    Salary or commission?

    How does Navien pay?
    To learn more about this professional, click here to visit their ad in Find A Contractor.
  • IronmanIronman Member Posts: 3,541


    That's my point exactly. Sure we can get more than 50k btu's if the delta T is widened, but that means a lower return temp. If I have 140* return temp, does anyone think that is sufficient for series looped baseboard that was designed for 170* average water temp? Even if the series loop is the secondary of a p/s system?

    The "Home" boys (who are probably one and the same) have yet to answer that. They keep making claims and campaigning for their product, but don't deal with anything factual.

    HDE, aka HomeDepotEmployee, do you really work there?

    Homeowner1, is that what your parents named you?

    Unless you're willing to post your reall identity, I'm gonna assume you're nothing more than paid bloggers. Anonymity carries no credibility.

    And just for the record: as I've stated before, I've had no issues with the Naviens I've installed. My issue is the misleading claims by anonymous individuals.
    Bob Boan

    You can choose to do what you want, but you cannot choose the consequences.
  • HomeOwner1HomeOwner1 Member Posts: 134
    Call up Navien then

    Argue your point with Navien then and let us know please.
  • IronmanIronman Member Posts: 3,541

    I have done just that with their instructors in training classes and after some evasiveness, they have conceded that my point is true.

    Once again, your little barb proves pointless and you continue to remain anonymous and evade answering the challenge of the facts.
    Bob Boan

    You can choose to do what you want, but you cannot choose the consequences.
  • TonySTonyS Member Posts: 849

    Dont waste your time, this argument is old and the answer is obvious. You are correct.
  • GordyGordy Member Posts: 7,122
    I wonder

    ,,When not if in the future HO1 will let us know of issues on this great product. I will bet not. New to the scene give it time they will ALL come where? looking for help,

    Tired of he product push, and the debate. Like Chris said there is no Chris Angel in the boiler room. And proven formulas do not lie.
  • IronmanIronman Member Posts: 3,541
    I Know, Tony

    The argument is old and I'm tired of it ,too.

    But I'm more tired of having to deal with folks, whether here or in person, that have drank this koolaide and think they're getting a product that can actually do what the Home boys are claiming.

    As Gordy said, people come here for help. They should get that, not mis-leading sales pitches.
    Bob Boan

    You can choose to do what you want, but you cannot choose the consequences.
  • GordyGordy Member Posts: 7,122
    How they pay

    Piece work?
  • ALandALand Member Posts: 1

    Any thoughts on the Navien NCB-240.

    I Have approx. 2600 sq. Foot with an extension

    To be done down the road bringing me to 3600 sq.foot

    Right now have 2 bathrooms

    Will end up with 3-4 bathrooms.

    Getting gas installed and converting from my

    Dinosour eating a whole in my pocket:)

    Anything will be better then whats there

    Making decisions!
  • HomeOwner1HomeOwner1 Member Posts: 134
    It works for a home that size

    My home is that big and it works just fine.
  • ChrisChris Member Posts: 3,056
    What's The Size

    Of the home have to do with it. The question is, What is the hot water demand and what is the heat loss of the home. You know better HO1..
    "The bitter taste of a poor installation remains much longer than the sweet taste of the lowest price."
This discussion has been closed.


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