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.

geo_1111

My desire to have a dropped header along with the basic 2 riser supply was denied due to inability to remove plug on the other supply tap. The return took the circuitous route as well. If your curious about the level of effort, chemicals, heat, 2.5 foot wrench with 5 foot cheater resulted in moving 8th rib left side out of bounds. I decided to oversize the equalizer since I had the fittings. Boiler has fired, been skimmed and blown down. I had the ball valve on the hartford loop closed in the hope I could purge the return without contaminating boiler. This system has not had a boiler attached to it for 13 years and it worked adequately then. Ignoring all the gross code violations which will be addressed, I'm seeking guidance to remedy the absence of vents hissing, condensate returning. The boiler was used and the plugs secured by previous contractor I assume, they don't move, they don't leak. Thanks any advice would be welcome.

Jamie Hall

You did a nice job of squeezing everything into a rather tight space.

As you know, Dunkirks -- or any side outlet boiler -- are rather fussy about near boiler piping, but that should be OK.

You do not show your controls. Your comment about vents hissing and condensate returning, however, make me a little concerned regarding pressure, however. You will need to be sure that your water level is controlled rather tightly (over filling isn't as bad as slightly low, but again with a side outlet isn't a good idea) but be sure that you pressure is kept low -- 1.6 psi cutout maximum.

geo_1111

Thank you for your input.
With regards to pressure, the 30 # gauge registers nothing, the comfort that gives is 0 as well. The vent on the top of the dry return emits nothing, above there is a spot where the high temperature stops, I suspect this is an obstruction. As I indicated this system hasn't had a boiler on it in 13 years. The low water cut off works and I haven't ventured far while it is fired, and I was waiting for the return output to assess the level of crud. Got some very dirty output, but there appears to be a fair amount of water that has not returned. The assessment of the system has been complicated by an uncooperative tenant. I have no experience around steam boilers and really not in a hurry to make a bad. Thoughts:

1) verify state in steam chest by cracking valve at skim port?
2) should probably verify clear passage in pigtail, # 1 should tell me something. 
3) remove main vent and use as access to flush return?

Thanks

Jamie Hall

Items 2 and 3 are a rather good idea. Also, a low pressure gauge to tell you what the system really is doing -- it can be mounted on the pigtail (usually) along with the pressuretrol. Y9u need to keep the high pressure gauge for your insurance and code people.

The vent on the dry return -- which is a main vent -- should release some air, but it may well be almost imperceptible. The steam is condensing in the radiators -- at least the ones that work! -- so there isn't much air pushing out.

geo_1111

I agree a 3 pound gauge would be more appropriate since the margin of error for the 30# may match the optimal operating range. The optimal trim is not my interest at the moment, verification of safe operation, solving issues that prevent that objective. The status of the tpv valve is a concern if it won't close, that is why I thought checking at the skim port was definitive and quickly stopped. The side supply taps are what is available and as it turned out only one. The lack of return water is a puzzle. 
I have had the valve on the return open all this time, is that preventing the pressure from building?
If you have any suggestions regarding a source for troubleshooting it would be appreciated, I'm going to check the manual, where I probably should have started.

Steamhead

On a boiler that small, one 2-1/2" steam outlet should work fine. And it looks like you removed a couple walls...............

geo_1111

Thanks for the input, I got access to the radiators cleaned all the vents, the pigtail, productive flush on the return. I have a calm quiet radiant heat. I'm a fan, the clanging of impeller springs, the cold domain topped with the pending shower, full pipes combined with extreme pressure provide. Putting this boiler in service was a very foreign means of hydronic at the start, I've learned to appreciate its principles and uncomplicated delivery of energy that makes a space your home. I probably will buy Dan's book, it's referenced so frequently I feel you've all shared a good portion. Your willingness to share your knowledge makes this forum an invaluable resource, thank you.