1 or 2 raisers?

The manual for that boiler states 2 1/2” riser and header which is the answer to your question about a 2” header.

I would follow the boiler manufacturers minimum requirements.

You don't want to do it the find out you have to re-do it.

The larger piping will be more tolerant of the oil that accumulates in the system between skimmings as you get the oil from the new piping out. If it were my system I would keep it the size of the tappings in the boiler or the minimum from the manual, whichever is larger for both the risers from the boiler and the header.

If the water quality is perfect the header doesn't need to separate anything but the bigger piping will let you spend less time skimming.

look in the manual it wiil show a drawing of the piping for your boiler

The manual does not say that the boiler has a 2 1/2 in tapping for the supply. The manual just suggests using a pipe size of two and a half inch. The boiler does have two, three inch Supply tappings. But the manual does not recognize the one on the right side. But you are certainly welcome to use it.

This seems like an easy and reasonable solution. Unless you really want two risers.

@patrykrebisz

I understand you trying to save work. Don't do it. Steam does not always follow things that make sense.

The inside of the new boiler does not match the inside of the old boiler. It is not the right choice to do a cut and slide.

Might it work…yes

Might it not work…yes

Do you want to pull it all apart and do it over if it doesn't work?

If it doesn't work and you call the mfg they will tell you to do it right. No one can predict what will happen. If you want to try it go ahead.

For those who don't know the easy way to find the surface area of a circle is radius x radius x pie.

For a 2" riser you've got 1 x 1 x 3.14 = 3.14. So 6.28 for two

A single 2.5" would be 1.25 x 1.25 x 3.14 = 4.9

A single 3 gives 7.

it has to do with the internal geometry of the boiler too. some may have more space for the water and steam to separate before it gets to the riser than others so the riser has to do less work letting th water fall out of the steam.

.7854 is easier for you to remember than pi?

Who doesn't like pie!

Corrected for my error in parenthesis.

If I remember correctly Mr. Holohan has written that 2 or more (riser pipes from the steam chest) is ideal for making drier steam as the steam vapor has more room to rise with more openings allowing it to leave the steam chest safely and rise into the header piping to reach the radiators faster and keep them hotter longer as long as all the vents are working as they should by expelling the air in the radiators as the steam enters the piping and then into the radiators.

It seems that having one or two three inch risers will only help you make drier steam using a drop header or double drop header.

The three inch pipe will cost more but it will allow you to have greater thermal mass to create drier steam that will heat the radiators and in the process heat them at a higher temperature to allow them to shed heat longer.

Paul and Chris both provided the math supporting the two 2" piping providing greater flow are than single 2.5 (6.28 versus 4.9). They just didn't say "Yes, it should be fine"

😀

follow @EBEBRATT-Ed -recommendation to use 3" to 2" nipples for the boiler to piping

My EG-40 has two 2" risers into a 3" header.

If I was doing it again, I'd do a single 3" instead. More flow and easier to pipe. I was stuck on using both supplies rather than doing what would be easier and better at the same time.

As far as a single 3" up into a 2" header………… I don't know, but Paul's videos suggest it would be perfectly fine and the 3" coming out of the boiler would certainly slow things down in that area for sure.

Mattmia2,

My mistake, I was thinking about the greater amount of metal in the three inch pipe in general terms and I neglected to mention- I forgot actually that the steam would slow down and the heavier water droplets and mist would drop out.

have you tried it with other boilers? there is probably a reason why peerless boilers are preferred for steam. do we see many people with problems with water being thrown out of peerless boilers?

As shown in the drawing in the first post, I'd go with one riser — when using two risers, swing joints are needed. They are not shown in the sketch, but maybe they are there… If not, it'll be cheaper and more effective to go with one riser, and going up in size.

I learned in physicist school / vacuum technology class that laminar flow in a round pipe — assuming a fixed pressure differential — goes with the THIRD power of the diameter of the pipe, not the square.

The square gives you cross-sectional area, but laminar flow means the gas' velocity is zero at the pipe surface and fastest in the center. That velocity profile is where the extra power comes from.
Two 2" pipes give 2 x 2^3 = 16.
One 2.5" pipe gives 2.5^3 = 15.6 — so, basically the same.
One 3" pipe gives 27.

From a practical point of view, not a lot of folks have access to pipe threaders > two inches… any plumber worth his salt will have that. That's where to 2x two-inch pipes & swing joints can make sense. It's what I have on my boiler — with a net rating of 308 sq. ft. — and it's fine.

And finally, I agree with Paul about good water quality covering just about any piping sins. But I'm on a two-year journey to skim all the oil from my water, and I think™ I'll finally be done once the third season gets underway. I did have serious surging at times, and once the oil is in the system, it takes a long time to return to the boiler. Since I'm not putting any new oil in, I know it'll get fixed, but I'm amazed by how long it takes.

If corners are cut on the piping, and I'm not saying that would be a bad decision, I'd think hard about what I'd do to keep my water clean. I'd probably start with carefully wiping all my new pipe threads with rags and alcohol and then washing with hot water and Dawn liquid soap in a big container. I wish I'd done that. Also wash out the boiler itself with "washing soda" before you send steam to the main.

because the boiler block may expand at a different rate than the pipe, just like with the risers. technically soemwhere between the header and the return connection from the equlaizer/hartford loop. usually you end up with enough play in there somewhere if you do it with threaded fittings.

It is right here. They don't tell you why they do most of the things they do.

it will let this section of pipe move with the boiler possibly along with rotation at the hartford loop fitting. it doesn't take much.