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  • Chuck_36
    Chuck_36 Member Posts: 42
    2\" mains in an old gravity system

    Should the EDR for the 2"Dia mains supplying to and returning from the radiators be added to the individual radiator EDR calculations in order to properly size a circulator pump?
  • DanHolohan
    DanHolohan Member, Moderator, Administrator Posts: 16,090
    This will help

    Retired and loving it.
  • zeke
    zeke Member Posts: 223

    Quote"When servicing old hot-water heating systems that originally circulated by gravity, but now use circulating pumps, I began to notice a lot of oversized circulators. In some cases, the circulator was so severely oversized that the boiler could hardly get any heat out to the radiators. The water couldn't pick up much heat in the boiler or shed it in the radiators because it was moving so fast. There is very little resistance in the large pipes of a gravity system, so the"

    I am puzzled by this. Does it really mean that the boiler water is somehow short circuited?

    It defies my intuition but is of course wasteful of power.

    Could somebody explain this?
  • zeke

    Many guys thought you needed a larger circ to make the water go to the furthest rad, in reality it made the heated water short-cycle to the closest circuit on the pump.
    As Dan said, usually overloading the circs motor and leaving the farthest circuits underheated.
    Converted gravity systems only need the circ to provide a slight nudge.

This discussion has been closed.