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Lochinvar Knight or WM evergreen, 399btu

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acaciolo
acaciolo Member Posts: 12
in Gas Heating
Hello!
You guys have given me some great advice in the past, and now I am starting anew house that I need a little help with. I am a custom home builder and have a great partner/hvac company that is super knowledgeable.

I am starting my personal house and looking at either the WM evergreen (readily available locally) or Lochinvar Knight using Natural Gas. I like the remote connectivity of the Lochinvar and their control system seems awesome, but I have heard about a bunch of heat exchanger issues (not sure if it is blown out of proportion or not.) Lochinvar doesn't have a terribly strong presence in our area, but parts etc. won't be a problem. My installer is more familiar with WM, but has done a few Lochs and liked them. My current house had a 16 zone, tekmar controlled very complicated system with a mix of radiant and hot water. I am looking to simplify in this new house...

It will be powering 4 hydronic coils in 5 ton air handlers and a radiant zone. It will also do DHW. I searched the forum and found lots of opinions. Anybody have advice either way? Cost is about the same.

thanks!
tony

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  • GroundUp
    GroundUp Member Posts: 1,908
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    Might I ask how big this house is? 399k seems like an awful high heat load, did the installer perform a load calc? I am not familiar with the WM, but I have installed hundreds of the 400k+ Knight boilers in commercial settings and they've been fantastic as long as water chemistry and HX is properly maintained. A lot of the failures you hear about are due to low flow and lack of maintenance, we've had terrific luck with them when properly installed and maintained.
    mattmia2
  • acaciolo
    acaciolo Member Posts: 12
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    It is about 9000sf and there is a 3000sf garage that is heated too.   Plus a heated basement of about 3000sf.

    The 399 sounds big but it actually just about right. Thanks! 
  • mattmia2
    mattmia2 Member Posts: 9,660
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    you might think about cascading 2 smaller boilers too. it will give you a higher turndown ratio and some redundancy if one fails.
    Zman
  • Gary Jansen_4
    Gary Jansen_4 Member Posts: 77
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    I'm partial to the Lochinvar.
    But, if you were me, and the budget can handle it, I would do either 2-199's, or a 199 and a 285.
    Greater turndown, less cycling, better matching the output to the loads, redundancy, more efficiency.
    Cascade them together.
    If you did the 2-199's, you would match your total theoretical load, and if you lost one boiler, you could possibly keep the system at a reasonable temp, maybe not comfortably, but enough to somewhat maintain the space.
    If you did a 199 and a 285, then the 285 could conceivably carry the building on its own.
    Good luck, Gary
    mattmia2ZmanTinman
  • acaciolo
    acaciolo Member Posts: 12
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    great advice. I did consider that, but since natural gas is so cheap in my area, I was having trouble justifying the extra expense. The main A/C units are actually heat pumps, so I do have that in case the boiler goes down. I did like the new weil mclain eco boilers, but they can't be cascaded yet.

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