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dropped header

Ken_40 Member Posts: 1,320
Dimension 'A' has little to do with the reasoning behind dropped headers - and everything to do with the 24" requirement between the water line and riser-to-main connection point, which is a function of making sure the steam has as little water-carry following along, allowing steam to be as "dry" as possible.

Dimension 'A' is critical in regard to water backing out the boiler via the Hartford loop and rising back into the main - potentially blocking the end-of-main air vent - and/or creating an anvil chorus from the collision of steam imploding against backed up cooler water.

When the NOWL (normal operating water level) in the boiler is less than the 24" critical dimension for "dry" steam, one must either put the boiler in a pit, or use a dropped-header to compensate and get back to at least 24" - either thru lowering the boiler into a pit, or using a dropped-header to compensate/overcome the under 24" "issue" of the actual NOWL.

Right church, wrong pew.

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  • Dan_43
    Dan_43 Member Posts: 50

    When is it necessary to drop the header?
  • kevin coppinger_4
    kevin coppinger_4 Member Posts: 2,124
    whenever you...

    are unable to get the A dimention w/ standard practices. That being said many stilll drop the header to simplify piping and get better steam....kpc

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  • More on this....

    As Ken has stated, the dimension from the NWL of 24" is critical but that is to the boiler header. Then there is a riser pipe from the boiler horizontal header that connects the header to the system main(s). It is also desirable to have a fairly good vertical distance here as well. That's where the dropped header comes into play. You will get the required 24" minimum from the boiler NWL to the header and then the header will drop down a short distance allowing for an extra increment to have a taller riser pipe from the header to the system.

    The dropped headers also slow the steam velocity down a bit due to the extra turns and creates much drier steam by cutting out more condensate. One more advantage has been that if the boiler is equipped with a tankless heater or indirect heater it helps prevent migration of heat up the steam mains while producing domestic water.

    Glenn Stanton

    Manager of Technical Development

    Burnham Hydronics

    U.S. Boiler Co., Inc.
  • Dan_43
    Dan_43 Member Posts: 50

    Thanks for the responses, I thought, it might be away around the 24" minimum. Which leads into my other (2) questions.
    I have about 43" from the water line to the tops of my mains. Am I better to run my header up nearer the mains or run just above the 24" mark?
    2nd Qustion:
    For better placement of the boiler I want to run 45s out of the boiler to the header. is a good idea, or not? I still plan on running a short horizontal as the installation guide shows, (unless you all say it not necessary to run the horizontals to the header. I am instaling a Burnham IN7.
  • Steamhead (in transit)
    Steamhead (in transit) Member Posts: 6,688
    All good reasons so far

    another is that if the boiler has two or more risers to the header, the extra swing joint in a drop header makes it much easier to put together.

    With regard to riser height between the boiler and the header, if you can get more than the 24-inch minimum it will help produce even drier steam. So will using a larger pipe size in the horizontal portion of the header. That pipe size is a minimum specification, as is the 24-inch riser height.

    Dan, how do you plan to use those 45s?

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  • Dan_43
    Dan_43 Member Posts: 50
    the 45s

    I am planning to come out of the boiler's taps with a pair of 2" x 8" nipples then(in tandem)a 45 - 10"nipple - 45 4"nipple 2"x3" bushing and into the 3" Tee (the header)
    I hope I was clear enough.
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