2 Risers vs 1

PoponPachaug

Hello Steam Users and Jnstallers,
I have recently purchased a new replacement Boiler. The Boiler is a Williamson GSA-125-N-I-P unit slightly oversized with Rated Steam supply of 321 sq ft. I have calculated a Steam EDR at 265 sq ft.

My question is this: Would a Single Riser or Two Risers be better?

The existing primarily 2 inch Main Steam system always worked fine, good slopes on the one pipe parallel flow system with no hammer.
Williamson shows a One 2 1/2 inch Riser to 2 1/2 inch Header.

But in the Manual Cutsheet for the Boiler, (Picture attached) It shows a Items 2 & 10 End Sections with Supply Tappings to install 2 Risers.
This would allow 2 inch Risers and 2 inch Header to feed into the existing 2 inch Steam Header without reducing.

Any thoughts and opinions are greatly appreciated.

PoponPachaug

mattmia2

2 risers are better. 1 riser is adequate in smaller boilers. Don't reduce the size from what the manual specifies until you get to the main. Make sure you get the risers, the main connections, and the equalizer in the right order on the header.

The larger piping slows down the steam and allows more of the water to fall out of it.

Make sure where you do the reduction doesn't create a place that condensate can be trapped.

pecmsg

25 + % larger isn’t slightly!

pedmec

you always follow manufacturers recommended installation for the best dry steam possible. they have done all the r&d on there product.

(2) two inch risers should work as the total area of (2) risers is 6.28" and (1) 2-1/2 is 4.9". But you still need a 2-1/2 " header to separate the steam from condensate to produce dry steam. the header absolutely needs to be 2-1/2. So i would find it it easier to pipe it with 2-1/2". its a lot less piping and fits into a tighter spot.

SteamingatMohawk

This is a chart I built earlier this year. It is based on a maximum velocity of 25 fps. Hopefully it is helpful

PoponPachaug

to SteamingatMohawk: Thank you for the Steam Velocity Chart

The graph makes it very easy to see and understand the Rate of flow for various pipe sizes since the goal is to slow the steam down to minimize water carry and make the steam dryer.

SeanBeans

I always use both tappings. The really old steamers had a steam velocity exiting to boiler of around 13-17.. nowadays it's upwards of 25-30fps with a single pipe. 

ChrisJ

You need to go with whatever the equivalent to a WM EG35 is.

And in both cases I'd be going with a single 3" riser not two.

PoponPachaug

WM EG-40 is more equivalent with 125,000 MBH Input and 325 sq ft Steam to the Williamson GSA-125.

WM EG-40 Manual recommends a single 2 1/2 inch Riser and Header, Same as Williamson GSA-125 Manual.

Thank you for all the input.

ChrisJ

PoponPachaug said:

WM EG-40 is more equivalent with 125,000 MBH Input and 325 sq ft Steam to the Williamson GSA-125.

WM EG-40 Manual recommends a single 2 1/2 inch Riser and Header, Same as Williamson GSA-125 Manual.

Thank you for all the input.

Yes,
But you want whatever the equivalent to an EG-35 is, so maybe a GSA-100?
I'd still use a single 3" riser, not 2 1/2".

ScottSecor

We've installed many Weil McLain EG boilers and a bunch of Williamson (Union Steam locally) for residential steam systems.

At the end of the day, skimping out on piping does not pay. For the EG 35, 40 and 45izes, why not just use the full size tap in the top of the boiler. As far as I know the W/M has some of the widest sections that allow a three inch riser (or two), why not take advantage of that. Use a single three inch riser with a three inch header, no need for a hard to crank bushing in the top of the boiler, no need to worry about high velocity, wet steam, carryover etc. Use three inch steel pipe with cast iron fittings and be done with it. If you really like to pipe things you could use full size (3") double risers, but I don't see the point on small boilers in this size range.

Yes, I'm aware that many are piped in 2" copper and 2" steel and the 2" inch is roughly half the price of the 3". Yes I'm aware that 2" is much more available than 3" pipe and fittings.

SteamingatMohawk

You are quite welcome. I created it from information in Dan's book, The Lost Art of Steam Heating. If you don't have a copy, it is well worth the cost. There is an excellent discussion about velocity, including both the modern rule of thumb of 25fps and the early days where the lower velocity mentioned by @SeanBeans is discussed.