Drop header

SC

What's more important installing a drop header or installing a normal header 24" above water line to comply with manufactures specs? Please see previous post New boiler- vents spitting water TY

Jamie Hall

In my humble opinion...

based much more on theory than on experience! -- you need to go up the 24" anyway; that will help drop out a good deal of the drops and splashes.  Needs to be vertical.  Then, a drop header (go over, then back down) will help a lot, as in a dropped header the steam (and water drops) come in from above, and the water can collect on the bottom where nothing is coming in and flow its peaceful way to the equalizer, while the steam does its thing in the space above.

Brad White

The Rise, The Size, Eyes on the Prize

There are many more systems installed without dropped headers than with them.



But of those in the majority without dropped headers, the ones with the fewest problems (specifically wet steam problems), have appropriate if not generous initial riser heights AND riser diameters. It is all about exit velocity off the boiler. 



In other words, if you necked down your initial riser diameter (say a 3" down to a 2"), you have cut your exit area by 56% and increased your exit velocity by 225%. Additional height cannot compensate for that the way additional diameter would.  What should be 25 fps would be almost 60 fps for example. It would take a lot more height (which I understand you do not have), to compensate for that. Water would be sucked off the waterline like a ShopVac.



So increasing the diameter to at least the boiler tap diameter is Job 1. Job 2 is to use a second tap if there is one, again, to lower the exiting velocity.



The dropped header comes into play here to,



1) Conserve height (allow the rise you need)

2) Recover the height (reset the starting point), to make your system connections

3) Allow excess moisture (whatever is left over after you have boiler risers of appropriate height, diameter) to be dropped off back to the boiler via the equalizer.



So in this case, the drop header can help compensate for poor upstream conditions, but if those upstream conditions are avoidable, they ought not stand.



In summary and in my opinion, you should have both.

Rod

A Dropheader Believer

A dropheader is the way to go as you have tall boiler risers to dry out the steam. Dan mentions that it's not a bad idea to measure "the 24 inches" from the top of the boiler to give you a bit more riser length.and by using a dropheader you don't run out of room with a low ceiling. Jamie and Brad have mentioned the other benefits. I don't understand why dropheaders aren't used much more often as they they have such a benefit especially with the ease of fitting when using two steam risers off of the boiler. I've attached a drawing showing the flow benefits of a dropheader vs a conventional header.  I also have attached a picture of a dropheader with high boiler risers, that was done by Dave Bunnell , "Boilerpro", a Chicago steam pro. Note how using a dropheader allows high risers yet the header is placed low enough so that the piping configuration from the header to the steam mains isn't cramped.

- Rod

SC

Pipe size

the boiler tap out of the boiler is 2" which is what WM recommends. However once you go to an elbow the recommend going 2" to 3" then your make-up header is 3". Risers going up then step back down to 2". Does that sound right or am I going to get that vacuum effect?

Brad White

If

the leaving boiler riser is 2 inches and is what the manufacturer recommends, that is what you should do. The sizes I gave were just an example, where reducing is "what not do do".



I have on occasion increased my risers (commercial work), say from 4" to 6", all going into an 8" diameter dropped header, so it does slow down the steam a bit- but only in the riser.



But I also know that at the boiler, you still have the net smaller size so the velocity there does not change. The size increase just spreads out the walls to give the returning moisture a place to cling to flow back down, if that makes sense. That is how I justified it. 



In other words, the up-size made me feel good, but the actual benefit is not something I can say is identifiable. It does not change the boiler exit velocity one bit.



No harm in sticking with the boiler tap size provided that the manufacturers piping diagrams show the same size as a "running size".



The header- also go by the diagram but as others have suggested, going up one size from what the manufacturer says, can give you an edge, more volume to allow condensate to drop and steam to rise. This is where the dropped header gives benefit to compensate for any compromise in riser height.



It all works together and the net effect of either is hard to define, but each helps the other do their job better. I hope that makes sense.

Rod

Dropheaders- Increasing piping size

Here's some  pictures of where the piping sizes were increased which I thought might help explain what Brad is talking about.  These were done by steam pros, from the left, the first and the second by Gerry Gill and the third by Norm Harvey of Boston.The first and third increase the size of boiler riser and in the second the size increases at the first elbow. Gerry Gill, a Cleveland steam pro, has a great website which has a lot of info on residential steam systems -   http://www.gwgillplumbingandheating.com/

From what I've seen of manufacturer's installation drawings, they should be taken as the bare minimum and not necessarily the optimum.

- Rod

crash2009

Rod

Do you have any idea why the Hartford was done this way?  I thought the equalizer was supposed to go to the boiler.  I also thought the Hartford should come from the wet return and not the boiler.  Is this a different kind of loop?

Charlie from wmass

One of the other guys here

was failed for piping it that way near NYC I think it was. Crash I would pipe it to the back of the boiler and had the return enter the equalizer through a close nipple. Wye's are rare as hen teeth in my area. They also reduced the pipe to the equalizer on the horizontal instead of turning full size and reducing. Dresser couplings on the steam supply pipes too?

Rod

Correction

Hi Crash & Charlie-  LOL...Thanks for pointing this out. Early this morning I just quickly ran through my collection of dropheader photos looking for something to illustrate what Brad was saying and used the first ones I came across with "expanded risers". Obviously I didn't look at anything else. I have decided to remove the photo as there was a name attached to it and I didn't want to embarrass anyone or have someone run across it in the future and be lead astray. Crash - Leave your photo in place as it has no name attached and with your's and Charlie's remarks, others can learn from it.

- Rod

SC

TY

Thanks to all. Let you know what happens.

crash2009

oops!

I didn't even think about all that.  I just thought, "What a beautifull header" and "Is that a new method of building a Hartford"  Thanks for the correction, I was gonna go get me one just like it.

Charlie from wmass

Sorry did not mean to offend

I was just trying to make sure the issues were not copied by a novice thinking that is the right way. I think the other thread about the press fittings for iron pipe got me wound up a bit. as always Gerry's install stands as a fine example of a drop header.

Rod

Thanks!

Charlie- I really appreciate you pointing out the faults in the picture.  Like you I wouldn't want any one to be mislead.

- Rod