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Lochinvar KBN151?

napnap Member Posts: 9
edited August 29 in Gas Heating
Hey folks -- looking for some more feedback here. Working with a new contractor on our boiler replacement (converting to natural gas). Good experience so far. He's advocating for a Lochinvar KBN151, which he says his supplier is discounting as they're clearing out on them ("last year's model"). This is for a 4-family house in Maine, ~3600 sqft. Honestly I can't seem to find too much information about the KBN series as it appears it was discontinued a couple years ago, but it doesn't look like it uses a fire tube design like the more modern (?) KHB/WHB series. I'm also a bit concerned about replacement parts for any model that is no longer being actively manufactured. Am I just being paranoid? Does anyone have experience with them? Thanks in advance.


  • IronmanIronman Member Posts: 5,926
    Yes, it is discontinued. And it does have the Gianonni heat exchanger which requires yearly cleaning. So that's and added expense. We're typically seeing fire tube HXs going about five years before needing cleaning.

    That boiler MUST be piped p/s or LLH or with a buffer tank to achieve hydraulic separation.

    Like all Knight boilers, it's very well controlled - probably more than what's needed on 95% of most residential jobs.

    Manufacturers are required to have replacement parts for 10 years after a product is made, but distributors are becoming more reluctant to keep them on the shelf if they don't move them regularly.

    Considering the higher cost of yearly maintenance and longer time it may take to get parts during a breakdown, is what you're gonna save on the boiler worth it?

    Loch makes some very good products, but there are less expensive options with 10 to 1 turndown available vs. the KBN.

    Has a detailed Manual J (or equivalent) heat loss calc been done?
    Bob Boan

    You can choose to do what you want, but you cannot choose the consequences.
  • G Averill_2G Averill_2 Member Posts: 45
    The KBN series is a water tube design heat exchanger, not a fire tube as you have noted. There are a lot of water tube Knight boilers installed. These were replaced by the first generation firetube KHN/WHN, which were then replaced by the current KHB/WHB firetube. Operational replacement parts should be available into the future. If I were to worry about anything being available it would be the water tube heat exchanger if it were to be out of warranty one day.
  • napnap Member Posts: 9
    Thanks for the responses; that pretty much reinforces what I'd been reading so it's good to hear confirmation from some experts. Heat loss calc says 138k BTUs to heat the building and contractor said plan on 10% in either direction. We have a combination of radiators and baseboard across 4 apartments. I've asked for a price on the KHN/WHN which the contractor initially indicated would be significantly more expensive. Let's see what he comes back with. He deals mostly with Lochinvar and Bosch it seems.

    Tbf we were originally working with another contractor and looking at installing a Veissmann (vitocrossal) but the guy suddenly disappeared on us without warning and then came back later to say he lost some help so couldn't do the job any more. Ugh. Now that we're already getting into fall we're feeling a bit of pressure to get it taken care of heh.
  • That heat loss number is pretty high (38 BTU’s per square foot). Older windows perhaps? Not fully insulated?

    The Viessmann Vitocrossal CU3A is a wonderful boiler and is one of the first boilers available to change direction to larger water content vessels. A great choice for gravity conversions that have large water capacities. 

    As far as the Lochinvar offer, the fire tube design is preferable and worth the extra price; self-cleaning. And if anyone has noticed, most manufacturers are committing to this design. 
    Often wrong, never in doubt.

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  • napnap Member Posts: 9
    edited August 29
    Yep - very old house (1890s). older windows for sure. Replacing a bunch of them this fall. In fact all of the windows in one unit... That's a whole other drama...

    Do you think we're at risk for over-sizing? I guess should I point out that sqft number includes a converted basement unit; not sure if that makes a difference. If it's helpful, I can copy+paste our baseboard numbers....

    I'd read really good things about the Vitocrossal and was pretty comfortable with the setup described there so it was kind of a blow when this first guy just dropped off the radar. The contractor we're working with now appears to work exclusively with Bosch and Lochinvar, which I'm okay with also, just want to make sure we know what we're getting and won't regret it in 3 yrs... cost now vs amortized cost over 15 yrs etc...
  • The newer Lochinvar's have "Rate Limiting" settings that allow you to reduce the maximum output of the boiler.

    If you are using the boiler to heat DHW (domestic hot water), the boiler will forego the limiting and ramp up to full blast.

    Whichever boiler you go with, make sure they are available locally and have a full selection of replacement parts. And check and double-check your contractor's references and that he lives close by. Wouldn't hurt to know that there are other contractors in the area that deal with the same manufacturer.
    Often wrong, never in doubt.

    Click here to learn more about this contractor.
  • napnap Member Posts: 9
    We plan on keeping the 4 separate hot water heaters (tenants pay separately).

    Anyway sounds like if we're going with Lochinvar the newer khn/whn units are the way to go, even with the added expense (or if we were going with veissmann the unit I mentioned is good... but this guy doesn't work with veissmann stuff).

    Still waiting on a response from the contractor so we'll see what he says the difference is. I'm sure he's just trying to save us some money but is there any reason he wouldn't want to install the newer lochinvar I wonder?

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