Navian condensing combi, good or bad?

rickyk22October 2, 2013


I am looking into converting from oil to gas and it was suggested that I get a navian condensing gas boiler/water heater. I was wondering the pros and cons to this as opposed to a boiler with separate water heater. also, how are the navian boilers? any other brands I should look at and is a condensing boiler what I want?

Thanks for the help.

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WeâÂÂve had good success and experiences installing Navien Combi boilers. You can also look at Buderus and Viessmann.

If I were choosing for myself I would probably go with a gas combination boiler as it takes up much less space in the mechanical room and is very efficient. Everything is hung on the wall and takes up no floor space with easy venting too. It would definitely be a plus for resale value as well.



Here is a link that might be useful: Navien Combi Boilers

    Bookmark   October 2, 2013 at 9:14PM
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Thanks. I just wanted to make sure that one unit would be able to handle the heat and hot water in our house. We have an approx. 3000 sq ft house that has forced air heat and we also have approx. 600 sq ft of radiant heating as well. I know that the condensing combi is good for having draw after draw, but I was wondering how it would be able to handle radiant heat, forced air heat, shower, washing machine, etc, etc all at one time?

    Bookmark   October 3, 2013 at 9:15AM
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Contract with an experienced, reputable installer. They will have to come on-site, evaluate your situation and youâÂÂll have to trust their expertise. Sounds like you may be installing 1-boiler, which is fine, to perform several different functions that may require different flow rates and water temperatures. Make sure you contract with a company that is up to date with âÂÂstate of the artâ integrated hydronic systems and controls so that you will have reliability, comfort, and energy efficiency, perhaps even remote access capabilities and monitoring.

Configuration of the system plumbing is crucial, one mistake and everything may be shot to hell till itâÂÂs analyzed and corrected. The installation should be clean and look pleasing to the eye. There should be sufficient cut off valves bracketing all major components to allow for easy servicing without draining the entire system, saving time and money.

Modern integrated hydronic systems use ECM variable speed circulators whose function may be based on âÂÂT or âÂÂP. These ECM circulators have permanent magnet rotors and may require enhanced dirt separators with magnetic particle separation capability to keep these micro particles out of the system as they spin off and migrate from the rotor into the system. Dirt and magnetic particle separation devices along with air separators should reduce nuisance service calls.

As with geothermal, there should be 3-copies of âÂÂAs Built BooksâÂÂ, 2-printed manuals and 1-digital on disc with 1-printed manual kept in clear view in the mechanical room explaining in detail the plumbing, flow, operation, wiring and controls of the system so that any experienced tech or engineer can come on-site and easily understand whatâÂÂs âÂÂsupposedâ to be going on without wasting time and your money trying to figure it out. All pipes should be clearly labeled with flow arrows (Supply, Return)! This will also enhance the resale value of your property when a prospective buyerâÂÂs home inspector evaluates the mechanical systems of your home.



    Bookmark   October 3, 2013 at 11:02AM
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I'd like to revive this thread to see if anyone else had more feedback (pros/cons) of a condensing boiler/combo heat/hot water unit like the Navien Combi. I don't know anything about how consdensing boilers work (until today, only thought that there were 2 kinds of heating systems- forced air or hot water baseboard). Will absolutely be speaking to a reputable installer, but would like to go in knowing a little about these systems.

We are building a new home (single story)- and will be using propane (no nat gas available), and forced hot air. The home will be 2600 sq ft, plus finished basement ~1500 sq ft.

How do these systems work? I understand there are 2 air handlers. Do they need to be located far away from each other? How does the system handle 1 person showering, dishwasher running, and heat kicking on. Will there be a loss in water pressure?

Thank you!

    Bookmark   February 8, 2014 at 8:35PM
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We also in the same position and i was wondering if you ever installed yours and whether you like it? We were offered to install Navien model NCB-240-Ng and i was looking for some feedback.


    Bookmark   April 2, 2014 at 12:12AM
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Sorry for the delayed response, i didnt see this in my email until the other day. We did end up installing the Navian NCB-240 in our house. We have approx 3,000 sq ft house. we have 2 stories and 1 zone heating in the house and it is forced air. In addition we have radiant in the kitchen, foyer and laundry room (550 sq ft). we are very happy with the unit. It is small, extremly quiet and works great. It handles the forced air, radiant and domestic hot water. We have no issue using the dishwasher, washing maching and shower together. It also handles the forced air and radiant at the same time with no issues. we are almost done remodeling our master bath so once that is done i will have a chance to try two showers at the same time. I am told that it shouldnt be an issue, the only issue being water pressure. the great thing is that it is unlimited hot water and we could take 100 showers in a row without running out of hot water (we have only done 2 in a row so far though). The only thing that I find is an issue is that it has priority hot water and cannot be shut off. what this means is that if there is a demand for domestic hot water, it will not provide hot water for the heat. I think a lot of the new boilers are this way though and the only time i think it would ever be an issue is if we had house guests during the winter and everyone wanted to take a shower one after the other. We received our 1st gas bill and it was $163 for 20 days. We keep our heat at 71 when we are home and during the cold months we were using approx 10-12 gallons of oil per day. We are in NY and this past month was pretty cold. Even if i halfed that and made it 5 gallons, it still would have cost us $439 for the same time period (5 gallons x $4.39/gal x 20 days) so you can see it is a substantial savings right off the bat. The entire install cost us around $8K including permit fees etc. I hope that this is helpful for you and please let me know if you have any other questions or would like to see pictures.

    Bookmark   April 7, 2014 at 7:52AM
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If it was the other way around and stayed in the heat mode and all you got was cold water in the shower, you would not be happy.
That's why all units give priority to domestic hot water.

    Bookmark   April 8, 2014 at 6:03PM
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Great Point!!

    Bookmark   April 8, 2014 at 10:13PM
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I am considering replacing my aging system with the NCB-240. I live 60 miles north of NYC. I would like to know what a fair price may be to replace and install.

    Bookmark   August 20, 2014 at 12:27PM
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hi William. my cost was around $8K. I hope that this is helpful.

    Bookmark   August 22, 2014 at 8:37AM
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I am contemplating replacing my oil boiler with a Navien NCB-240 Combi boiler. Is this too large for my home. I have 2200 sq ft of heating space

    Bookmark   August 23, 2014 at 12:12AM
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Sarah Glickman-Greenstein



First....your house only needs the NCB-180. the 240 is too big for the amount of space you have. Second....The machines break down all the time. They are crap. We have it and it has been nothing but problems since we bought it. Also...95% of plumbers will NOT work on the units. The ones that will charge an arm and a leg just to walk in the front door.

    Bookmark   last Saturday at 10:59AM
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The first question to be answered in the installation of a combi is, what are your hot water needs? Careful attention should be paid on this topic. If the hot water demands exceed the ability of the unit, then it is time to go for heat and hot water separately. So, what is your hot water requirement?

    Bookmark   21 hours ago
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