dimension \"A\"

Paul Fredricks_3

Yes, to the bottom of the lowest horizontal steam carrying pipe.

Luv'nsteam

dimension \"A\"

Dimension "A" is measured from center of gauge-glass to the lowest HORIZONTAL steam carrying pipe. Is this correct?

Luv'nsteam

riser height & dimension \"A\"

My system is under 100,000 Btu's. Per Dan, in "The Lost Art of Steam Heating" I need a minimum of 14" of dimension "A". Per install insructions of new boiler (and Dan) I need 24" from center of gauge-glass to bottom of steam header. Can these dimensions be combined? If they are, it will give me an "A" dimension of around 20".

Mark Hunt

Riser


height has nothing to do with the "A" dimension. Newer boilers have MUCH smaller steam chests than the ancients did/do so the new boilers use the riser to help seperate dry and wet steam. The 24" minimum height to the header from the water line is to allow for this seperation.

The "A" dimension is determined by two things:

1) The NORMAL operating water line of the boiler
2) The operating pressure of the system.

Page 25 from TLAOSH shopws that for a system operating at 1 psi, the total "A" dimension would be 28" from the normal operating water line to the bottom of the lowest horizontal pipe carrying steam. This is to prevent condensate from backing up into the steam mains.(For systems over 100k btu's)

In your system, a 14" minimum "A" dimension works with an operating pressure of 1 psi. (Under 100k btu's) You will probably find that your system had a 28" "A" dimension because as Dan mentions in TLAOSH, the old timers standardized it.

Hope this helps.

Mark H

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Paul Fredricks_3

These are 2 very different things. Dimension "A" lets the condensate return to the boiler, the 24" from the center of the glass to the bottom of the header is to give the steam room to drop excess moisture.

If under 100K BTU's you need a minimum of 14" in dimension "A", but more is fine.

Luv'nsteam

riser height & dimension \"A\"

Having read TLAOSH, I have learned alot. After locating my lowest steam carrying pipe (a dry return) I measured down to the water line and it is 14". With any new boiler, achieving the 24" water line to bottom of steam header, to take the place of the steam chest will put the water line lower than it is now. This will increase my dimension "A" as measured against said dry return. Is this ok to do? Or am I missing something?

Mark Hunt

It is


ok.

More "A" dimension is ok.

Mark H

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Luv'nsteam

steam header

My preferred boiler, as well as, several other MFG's that have online instructions, do not list the required header size. Do I use the same size header as riser? And increasing the riser from 2" (2" riser per instructions) to 2 1/2" the velocity slows from 39fps to 27.41fps. Is this a worth while investment (to increase pipe size)since all of the near-boiler pipeing must be redone?

Mark Hunt

Increase


the header size.

It's worth it.

Mark H

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Luv'nsteam

header size

I will certainly go with 2 1/2" riser and header, but I am curious, how is that supposed to be figured out if not in the MFG's installation sheet?? Also, thank you for your help Mark & Paul.

Mark Hunt

Ya' gotta' know steam


I know that Burnham lists the minimum size and the "recomended" size.

Anytime I use two risers, the header is increased.

You're welcome.

Mark H

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Ron Schroeder

Mike

Go to page 42 of The Lost Art of Staem Heating and read from there to page 46 your answer is there.

Luv'nsteam

header size

Ok. I just reread pg. 42-46. These pages do not tell me what or how to size the header. Not explicitly. Yes, they tell me the virtues of going to a larger header (better seperation of water and steam). They tell me how to calculate steam velocity, which I've done. All of that said, hows this for thought: the boiler MFG requires a 2" riser to header. With a 2 1/2" riser I get an exit velocity of 27.41fps. This requires a reducer. If I use a 3" riser and header, the velocity is decreased to 17.7fps. Much closer to the desired maximum of 15fps. So, weather I use a 2 1/2" or 3" riser/header combonation, I still need to use a reducer from the casting to the riser and another reducer from header offset to main. Casting tapping is 2", main is 2". Will there be a problem with condensation gathering in the reducer on top of casting or will the water simply drip back into boiler? As long as I use eccentric reducers from header to main, is there a problem going from 2 1/2" or 3" header to a 2" main?

Ron Schroeder

Mike

That would be a great reason to have an overszed header as you will drip out water before going the the main, bigger pipe slower vilocity it rains in the header, and runs off to the catchbasin ie the equilizer and dryer steam to the main. If you can slow the steam down to abt 15Ft per sec in the header then you will make it much dryer, i would bet that the twistes and turns of a drop header would be a good thing too as you get the water droplets to fall in the header as steam is rising.

Paul Fredricks_3

In my mind I see 2-2" risers going into a 3" header. If head room is an issue a drop header makes sense.

Ron Schroeder

Paul

I agree on the risers but I think he may be working with a single tap boiler, and that is why I was trying to get him to do anythng he can to get the water out before the mains

Luv'nsteam

steam header

Yep, it's a single riser guys.

Paul Fredricks_3

I didn't realize. So would you put a 3x2 reducer as close to the boiler as possible and run a 3" riser and main? I guess that would give plenty of room to wring out the moisture.

Luv'nsteam

dimension \"A\"

Yes. What I was thinking, was 2" to 3" reducer rite out of the casting. Rise up to 24" minimum above water line into a 3" 90* into a close nipple, into another 3" 90* (swing joint?) down into a 3" header reduced at end (on the down side) for the equalizer and (2) "T"'s 3" to 2" reducer into my two mains. I need to draw it out on paper and make sure it will comply with all rules (details!) as outlined in TLAOSH (my new favorite book) and of course, check with the profesionals on The Wall.