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Turndown Ratio Question

Cyclist77
Cyclist77 Member Posts: 40
in THE MAIN WALL

As a combi boiler has the turndown ratio is an oversized unit as much of a concern as a ci boiler?

Comments

  • Jamie Hall
    Jamie Hall Member Posts: 25,262

    No — but you still want to get close…

    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • mattmia2
    mattmia2 Member Posts: 11,145

    It becomes much more important if there is zoning involved. The more oversized it is, the greater chance that the lowest trundown ratio will be more output than the smallest zone can dissipate. The mass of a cast iron boiler can buffer somewhat. The low mass of a mod con is going to short cycle without some sort of short cycle logic on a zone that is smaller than its lowest turndown ratio.

  • hot_rod
    hot_rod Member Posts: 23,816

    If it is a combi boiler the turndown can be more important as you size to larger load. The DHW is often the larger load.

    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    mattmia2

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