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drop headers and the 28 inches

just want to be clear on something recently discussed here...and the question is about a boiler install i've got to do. i can run the supplies up to a height of 46" from the nwl before i make the 90 down into the drop header.

my question is; can i drop the drop header to a point below 28" above the nwl?  Does the drop header become the "lowest steam carrying pipe" from which the A dimension is taken?  i always thought that the critical thing was to give the supplys all the height you could and you could position the dropheader as low as possible to give you a good lead out of its top up into the main giving the steam a second chance to shed water.

thanks for straightening me out here.

Comments

  • STEAM DOCTOR
    STEAM DOCTOR Member Posts: 1,317
    drop header

    The drop header can be brought down as low as the top of the boiler. The 28"(aka A dimension) refers to the end of the steam main or dry return, not the header. The reason for the difference between the header and the steam main is that since there is reduced pressure at the end of the steam main and full pressure in the boiler you need the 28" to help the weak end of the main condensate push  against the full pressure in the boiler. The header on the other hand has the same amount of pressure as the boiler(more or less) and therefore can return water without the help of the extra 28". The header also has considerably less water then the water/condensate that is present at the end of the steam main.
  • steampunk_2
    steampunk_2 Member Posts: 28
    drop headers and the 28 inches

    i get it,  thanks very much.
  • steampunk_2
    steampunk_2 Member Posts: 28
    drop headers and the 28 inches

    i get it,  thanks very much.
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