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Expansion tank on Secondary loop?

Weil McLain and Munchkin both show the expansion tank installed on the secondary (system) loop instead of the primary (boiler) loop. Does anyone know why they do this, and what would happen if it was installed on the primary side? There may be other manufacturers doing the same thing as well. Is this a new piping practice or is it specific to their equipment ?


  • Bob Schultz_2
    Bob Schultz_2 Member Posts: 8

    I forgot to attach these pics:
  • DanHolohan
    DanHolohan Member, Moderator, Administrator Posts: 16,489
    I think

    the boiler loop would be considered a secondary circuit in this case.
    Retired and loving it.
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