Dunkirk psb2 close piping

geo_1111

I'm installing a 3 section boiler and I saw an install with 2 risers and the equalizer directly under one. The take off to the main was teed from the middle of the header. I like the simple setup and the equalizer is technically after the take off. I'm curious to know what the disadvantage to this could be, compared to one riser, tee to the main, 2.5" to reduce 90 bypassing supply to return? I have a poor picture if needed. 

EdTheHeaterMan

Two risers to a header with the main riser connected between the two boiler risers are a recipe for disaster. Don't Do it

Watch this video https://www.heatinghelp.com/systems-help-center/near-boiler-piping-in-steam-heating-system. Starting at time stamp 17:50 there are some boilers piped the way you described with commentary of how it won't work.

Steamhead

This sounds totally wrong, but post the pic anyway.

geo_1111

Thank you for your quick response, I was thinking the flow opposition might be an issue, then again, more volume with 2 risers and low pressure. I do not know how to post the picture.

geo_1111

geo_1111

Well that's it, I'm interested in your thoughts.

Ironman

geo_1111

Thanks for the input Bob, that illustration clearly shows the extra materials and time are worth it. That leads me to the next question; would you always commit to 2 risers for dryer steam? If no, what factor determines your choice of 1 being sufficient, other than the iom specifies 2 risers for 5 sections and greater?

EdTheHeaterMan

geo_1111 said:

Thanks for the input Bob, that illustration clearly shows the extra materials and time are worth it. That leads me to the next question; would you always commit to 2 risers for dryer steam? If no, what factor determines your choice of 1 being sufficient, other than the iom specifies 2 risers for 5 sections and greater?

The IO manual is the final word on wether or not you need 2 risers from the boiler.

The idea is to keep the steam flow rate as slow as you can, in order to keep the water in the boiler so only dry steam gets to the main(s). If you are confined by space, for example there is not enough room to go up 24" for the header, before you get to the main, then use a drop header. That means to go up the minimum 24" then two 90° elbows to point down so you can get the header below the main riser as shown in this photo

geo_1111

I won't be doing a drop header, I'm looking for a convincing argument for a 2nd riser. If I had pipe fitting that nice in my basement I'd move in with it. I do not have the space constraints like the gentleman whose install picture inspired this discussion, thank you. 

Ironman

Here’s what happens when only one riser is used:

From “The Lost Art of Steam Heating”. Available in the bookstore on this site.

Steamhead

With the 3-section, you can get away with one riser. BUT- that boiler has a 2-1/2" steam tapping. DO NOT reduce the size of this pipe. Put in a full 2-1/2" header.

The manual is here:

https://dunkirk.com/wp-content/uploads/2023/04/14683003-REV-P.pdf

mattmia2

Even if it isn't space confined a drop header does a better job of separating the water from the steam than a directly connected header.

geo_1111

Thank you, I've decided on 2 risers, maintaining 2.5". I believe I read the skim port should go through a reducer to elevate the level otherwise one section gets attention and the remaining 2 not so much. I will check the funds when the time comes regarding a drop header. Thank you all for your help.

Mad Dog_2

You won't regret it Geo...Listen to the Steam  Boys. The Steam can be VERY unforgiving if you don't play be her rules.. Its worth the extra muscle and fittings. Please post pics when you're done.   Mad Dog 

geo_1111

Will do, and will do. Thanks again

geo_1111

With regards to my 2 supply nbp, are online suppliers reliable and purveyors of quality materials? If this is a topic in the category of job pricing and not welcome, I'll stop here, Just let me know.

Ironman

Like anything else, it depends on which one.

Supplyhouse.com is good.