Steam Boiler Replacement

BG

Im in process of replacing an old Steam Boiler. At present it has three supply headers and two wet returns.
The old piping is setup like so, the supplies are off the top of the old boiler (1) 2 1/2" (1) 1 1/2" (1) 3"
The returns are (1) 1 1/2" on one side and (1) 1 1/2" on the other. My new Boiler Dunkirk PVSB-7D 225MBH has 2 1/2"
NPT Im wondering if I need to tye in both wet returns together at the floor before I pipe in my Hartford loop.
And Im going to pipe my supply and Loop in 2 1/2" from the boiler to the existing piping above the new boiler. The 3" will be reduced to 2 1/2" about 24" from the new boiler.

Al Letellier

new seam boiler

Every boiler comes with an installation manual. Pay attention to the piping schematics and follow them to a tee. Too many installers try to second guess. Don't become one of them.

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Boilerpro_2

I've worked with those Dunkirks....

Installed an 8D a year ago. Definitely use both 2 1/2 inch tappings and use a swing joint 3 inch header. I'd also run the 3 inch header at least 12 to 18 inches before connecting the first steam main take off to allow the steam and water to separate. As already stated, follow the directions, and install valves for skimming and blowdown...it makes getting that boiler water good and clean alot easier.

Boilerpro

Unknown

you are going to feed a two and a half, a one and a half, and a three, from a single two and a half inch header?

Do you think the dead men oversized by THAT much, or is a bunch of radiation removed? Something feels funny, to me.

I'd double check how much radiation is there, then size the boiler and header by the book, with confidence.

My gut says a 4" header will go there nicely. I could be wrong, though.

Just my two pennies...

Noel

Boilerpro_2

Good point Noel

hadn't really caught that. Vapor system maybe, or, as you said, lots of radiation removed. Mine was in that Moline system. I left the original 4 inch header in place with drip and feed it with the 3 inch header from the boiler.

Boilerpro

steve_6

piping

Doesn't the problem seem to be everyone seems to go to small instead of to big on their headers and equalizers. the lost art book recomends 3" or 4" headers and 2" equalizers for modern boilers

steve_6

headers

Noel, on one of your previous postings you had said that ,the idea of the header is to be bigger than the combined size of the risers, and bigger than the combined size of the steam mains. How would this work in this system? thanks steve

Steamhead

Steve, the reason we need a header

is to slow down the steam to the point where any water that came up with the steam from the boiler will fall to the bottom of the header. This is done by using large header pipes so the steam's velocity will decrease. If that one main really is 3-inch, you should use a 4-inch header as Noel said. But a 3-inch main on a system with a 225-MBH-input boiler sounds like it might be a bit bigger than usual, unless it's a Vapor system or some radiators have been removed. Did you measure the diameter of the piping in that main, or did you measure the fittings or the insulation (don't laugh, I've run into this rather often)?

I think in this case it would be good to know just how much steam is needed in each main. You did measure up all the radiators to determine their capacity in EDR, didn't you? Also, has any radiation beem removed? This will increase your pick-up factor.

Tell us more about the system itself. Is it a one-pipe system? Two-pipe? Vapor?



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