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1 boiler or 2 ? For CH and DHW

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CBRob
CBRob Member Posts: 273
in Radiant Heating
If your house requires say 240,000 BTU of boiler output, is there any benefit one way or the other by going with two smaller boilers or one full size?

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  • hot_rod
    hot_rod Member Posts: 22,157
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    what type of boilers? If you use mod cons you double the turndown 14:1 for example with two 7:1. You can also stage and flip lead / lag with many of the onboard controls.

    Redundancy to some extent.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • CBRob
    CBRob Member Posts: 273
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    For condensing boilers, looking at replacing a couple of 120,000 BTU boilers. They supply heat domestic hot water and snow melt for a 3000 square foot house. Cold climate.
    I'll look through some of those coffee with Caleefi YouTube videos and see if they have any explainethis in detail.
    The existing setup has Cascade control, just seems to overcomplicate things.
  • hot_rod
    hot_rod Member Posts: 22,157
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    what is the snowmelt load? dedicate a boiler to that as it is glycol.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • CBRob
    CBRob Member Posts: 273
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    That's a good idea hot rod.
    120,000 BTUs should cover the snow melt just fine.
    This is the house that has side-by-side Viessmann boiler,
    It's been most of the last year operating on just one of its two boilers.
    That one boiler was able to melt snow keep the house warm and do domestic hot water. It may have lacked behind a few times but the homeowner never noticed

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