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Good rated Combination Boiler?? Lochinvar Noble

jodan58 Member Posts: 3
edited January 2019 in Radiant Heating
Im a Remodeler/ homeowner looking for recommendations on a 2k sqft residential house, need a Combination boiler for - 1k sqft radiant floor heat on main floor and hot water supply.
My Mechanical contractor is pushing a "Lochinvar Noble NKC199N" 199,000 BTU HIGH-EFFICIENCY CONDENSING GAS COMBINATION BOILER.

is this a reliable unit? and brand.
instead should I consider separate units for hydronic heat and hot water supply for repair purposes?

Reliability and space saving are most key factors.

I'm seeing a lot extreme opinions and possibly biased views elsewhere, hoping this is an appropriate place for this post and question.



  • JohnNY
    JohnNY Member Posts: 2,624
    Lochinvar is top shelf equipment. 199,000 BTUs is good for the hot water side but overkill for the heat. However, the unit has a 10:1 "turn-down" ratio which means that it'll modulate its output down to about 20,000 BTUs when it is efficient to do so. I'm not a huge Combi fan but when it is practical to install one, this is the one I've been using for the past year or so without incident.
    My go-to DHW-producing preference is a boiler and indirect water heater which I feel eliminates the issues that plague Combi units like flow rates, lag times, temperature fluctuations, etc.
    Contact John "JohnNY" Cataneo, Master Plumber
    in New York
    in New Jersey
    for Consulting Work
    or take his class.
  • DZoro
    DZoro Member Posts: 1,048
    Lochinvar Noble is a very nice quality unit. Easily serviced, set up, control of heating side btu's, outdoor reset. Set up and installed correctly it will service you just fine.
  • SuperJ
    SuperJ Member Posts: 602
    Good boiler, but if you have the space in your mech room, inquire about a price for a smaller boiler and indirect hot water tank. I bet your heat loss is less than 60kbtu. You should get a proper manual J done, not just to size the boiler, but to confirm your radiant design (sizing/spacing/flow/temperature/etc) is appropriate. A smaller boiler is going to purr along more of the year whereas a bigger boiler even with a 10:1 turndown is going to cycle a lot more.

    Lochinvar's Knight Fire tube offers a 8000btu/hr low fire on the 50 and 80kbtu sizes versus almost 20kbtu on the combi unit you mentioned.
  • hot_rod
    hot_rod Member Posts: 14,566
    How much DHW are you looking for? You might step down a size or two, the 199 may be grossly oversized and more $$

    I have had a Nobel 120 in my home since they came out, it works fine for two of us. Recently my wife had to flow down the high gpm tub fill valve a bit, possibly I need to delime the HX.

    The control has all the nice features to customize to your system, easy to program.

    The smallest one should provide around 2 gpm reliably, plenty for showering,etc.
    With a tankless or combi you may need to change your DHW habits a bit, running one faucet at a time. Mine will keep up with a dishwasher and wash machine running at the same time.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • Le John
    Le John Member Posts: 196
    My original plan was for a KHB-55 and an indirect but space was tight so I opted for the Lochinvar Noble boiler NKC199. Awesome boiler.

    Has a very simple control and provides more than enough hot water, makes more than I can use. Even with the shower running and the sink faucet open the boiler fires between 40 and 50%. The only time I ever see it at 100% is when the washing machine is calling.

    If you have smaller zones I'd go with the NKC 150. It will produce 3.6 gallons per minute and modulate down to 15K. )

    During the last cold spell (Sunday Night Monday Night) the boiler ran continuous for almost 24 hours at 17% fire rate. (Thermostat at 70)

    It finally turned off yesterday during the day.
  • jodan58
    jodan58 Member Posts: 3
    Hey Guys thank you.
    I understand this is bigger than what I may need, but currently 5 people 3 baths, and the wife really wants to run the clothes washer and have capacity for 2 showers. 199 btu noble says 4.8 gph,

    could go down to the combi noble 150 if you all think its more appropriate for my needs.
    Again space saving is the priority , reliability as im reading a lot of reviews of consistent problems like ignition failure, but angry people do submit more reviews possibly.
    I have not looked into an indirect hot water heater yet, will do.
    And I am getting radiant sized curranty,

  • hot_rod
    hot_rod Member Posts: 14,566
    It’s more about how many loads you want to run at the same time. Lowflow showerheads? Hot wash and rinse or warm in the washer? If the DHW to heat load is too lopsided, a combi may not be your best option, as ther is a comprise to be made.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • jodan58
    jodan58 Member Posts: 3
    I don't want to have a low flow in the master shower, I do want to have the capability of 2 showers running at once. or just kitchen sink and one Shower.
    Washing machine is always warm and doesn't need to be incorporated into the equation as we rarely need to wash and shower at the same time.

    intent to buy 150 0r 199 combi
    Ideally 2 showers at once
    Floor heating is 2 zone total of 250 sqft zone and 750 zone.
    I feel like the salesman was being overly cautious , as I told him I was sick of dealing with hot water problems.

    this is extremely helpful Guys
  • hot_rod
    hot_rod Member Posts: 14,566
    Federal regs are 2.5at 80 psi
    California dropped to 1.8 a year ago
    for shower heads

    temperature of the DHW, incoming water temperature and system pressure with actual shower head flow are needed to give you an exact answer.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • Bigtrucker821
    Bigtrucker821 Member Posts: 8
    With all the DHW your thinking you will be using dont make the same mistake I made buying a unit that cuts out the heating side to satisfy DHW because your house will get cold and long cycle to get heat back up
  • Steve_Wheels
    Steve_Wheels Member Posts: 20
    I'm a believer i nBoilers and Indirect Water heaters, BUT there are a lot of nice combi's out there. The Nobel, The NTI FTV... they both use plate heat exchangers for DHW which are great but i do get complaints that some people feel they are effected by variance in water flow. you may want to consider something like the NTI VMAX153P that has a 16 gallon indirect built into it. Large diameter pipes and a little storage go a long way to solve flow issues.
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