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steam ?

larry_41 Member Posts: 1
As stated before if you take off form one side of a boiler there is the problem of short cycleing. this is because the water is ventured when leaving the boiler making one side low and the other high. it is like making a vaccum and sucking the water out from the side, The pipe is attached too.


  • Russ Stockton_2
    Russ Stockton_2 Member Posts: 7
    steam install question

    what is the reason for tying the two pipes on the top of the boiler together we usually use one, and cap the other to provide access for scuick. However the boiler paperwork always shows the two piped together, we have never had any block failures, we always pipe in an equilizer and a hartford loop.
  • Glenn Sossin_2
    Glenn Sossin_2 Member Posts: 592
    Draw off evenly

    I believe its to allow the steam to come off the water in the crown of the boiler evenly and prevent one end of the water line from dropping excessively and triping a LWCO to feed water to the boiler or possiblly shut it down.

    I'm sure there will be a few more responses to this.
  • Perry_3
    Perry_3 Member Posts: 498
    The engineering reason...

    This from an engineering view of how steam drums work in general.

    You would want to draw steam off from both ends (or multiple points) to prevent non-condensables (air) from getting flow trapped to one end of a steam drum. That could cause excessive corrosion of the steam drum (and any internals) if air and other things were not vented from one end.

    Even in the best of systems - the makeup water will introduce air and other gasses.

    So unless you have a very small boiler with only one pipe - you want to use both to provide proper venting of the boiler (note that small boilers with one pipe were classically designed with a pointy top with the steam exit at the point to provide just such venting.

  • [Deleted User]

    We take a somewhat different approach to how many risers we pipe to the header. We follow the manufacturer's instructions. Sometimes one. Sometimes two. Sometimes three. Number of risers is just one equation in proper near boiler steam piping.

    Do it right & leave the Squick @ the Supply House.

  • BAB
    BAB Member Posts: 118
    Reducing Capacity of Boiler

    Am I reading these posts correct or what ? If you have a boiler supplied by a boiler manufacturer with two steam supply outlets on top, ... you should, you have to, you must, use both of them. There are no options or preferences here, ever. Or as Ron said above, you "... follow the manufacturer's instructions". If you choose to do otherwise you definitely limit the boiler from producing at its rated capacity. If a 800,000 BTU boiler comes with two 3" steam outlets you tie them into a 5" main steam header. If you cap, plug, valve or limit one of the 3" steam outlet pipes you immediately limit the boiler capacity. The boiler will produce at about one half its rated capacity. It is like taking a new pump with a 4" pump discharge & reducing to 2" discharge piping.

  • clammy
    clammy Member Posts: 3,111
    steam velocity

    The main reason i understood for using both tappings are number 1 to slow the exiting velocity of the steam from the boiler high steam exiting velocity usually dump alot of carry over water into the steam main and cause sight glasses to bounce and also at higher velocities the steam leaving the boiler is not dry ,following manafuctures near boiler piping usuallt leads to less surging ,dryer hotter steam and less carry over moisture and more dry steam in your mains and rads and also lessen the amonut of condensate in your main which in connection with uninsulaterd main leads to groving and possible leaks in your steam mains at your tee's and always along the bottom of your steam mains ,the ideal exiting velocity from a steam boiler should be at a max of 15 fps the lower you get it the more btu's can climb aboard that steam trqain dry steam carries more btu then wet steam , laosh has the formula for fiquring out exit velocity all you need is btu ,pipe size and i belive condensate per hour it's all in the lost art thanks Dan for makling me kinda smart peace and good luck clammy
    R.A. Calmbacher L.L.C. HVAC
    NJ Master HVAC Lic.
    Mahwah, NJ
    Specializing in steam and hydronic heating
  • Jim Bennett
    Jim Bennett Member Posts: 607
    Good question !

    You have come to the right place Russ. This is a Great place to learn.

    Hang out here, these guys are the best in the industry.

    Ask questions and you will get the info you need.


    There was an error rendering this rich post.

  • Steamhead (in transit)
    Steamhead (in transit) Member Posts: 6,688

    If the boiler is not installed with the proper number of risers, the steam can get backed up in the sections. This will cause the waterline to tilt. You can't see this in the sight glass as it only reads the level at one point in the boiler.

    If the tilting water exposes the boiler's crown sheet, it will crack. Good-bye boiler.

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  • Chris_82
    Chris_82 Member Posts: 321
    Difficult to understand,...

    Something we still see a lot of on replacments is the ignoring of the man. reccomondations, esp with the equalizing headers. Apparently it is tough for many to understand why they are piping off the boiler in two inch imediatly increasing to 3, 4 and even 5 inch piping and then having to reduce to connect to the mains. Because it simply works better if you follow the advice of the manufacturer that has the benifit of many instalations over a long period of time. And also as others have mentioned it is important to equalize and ensure the unimpedid flow of condensate back into the boiler, allow the individual sections to move, and check how good you can be at measuring and cutting IRON pipe to get that big espensive union to look good.
  • btc
    btc Member Posts: 43
    Can there be too much of a good thing?

    Interesting topic--is there a problem in using two steam outlets on a small boiler (98K BTU) when the mfg documentation only specifies one??
  • Unknown

    Lower velocity is always better for the steam.

    There is a point that you won't notice the difference if you keep increasing the pipe volume out of the boiler, though.

    Use the installation instructions for the boiler, itself. When the manufacturer makes several size boilers by adding middle sections, there comes a point where one riser isn't enough, and the tapping in the section is already as big as it can be. Then you would use both tappings (or more, in big boilers) to get the steam to the system.

    If you use the smallest size boiler in the model line, the front and rear section will still be tapped, rather than casting two different fronts or backs. It's easier on the manufacturer. They may not require you to use both, but you may, if you like to.

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