1 riser vs 2

Snowmelt

What’s the benefits on one riser vs two, and let’s just for argument sacks using a Weil McLain steam boiler any size..
On the same subject what is happening to steam after a bull head tee after the takeoffs and what’s the benefit of separating the two and making an extra takeoff.

ethicalpaul

The velocity of the steam inside each riser is cut roughly in half. This helps prevent surging. Each manufacturer publishes in their installation manual how many supplies to use and what size they should be.

That's if you're talking about supplies from the boiler.

But you may be talking about risers from the header. The same general idea is at play, it makes a nice route for the steam to travel.

As far as bullhead tee above the header, I think it's mostly a mythical issue. The steam will go where the lowest pressure front is regardless of piping arrangement up there. Unless the water quality is truly horrible, there is no water above the header, or even in the header.

Before you beat me up, I'm talking about in residential steam (really any steam at those low pressures and flow rates).

The big complex issues of fluid dynamics just don't come into play at these velocities and pressures. The steam goes where the pressure is lowest, I'll say it again.

leonz

If I remember what Mr. Holohan said about risers and the number of steam boiler tapping's;
the more tapping's and risers the better as the wet steam will exit the boiler faster and create
useable heat sooner with the same amount of energy.

ChrisJ

leonz said:

If I remember what Mr. Holohan said about risers and the number of steam boiler tapping's; the more tapping's and risers the better as the wet steam will exit the boiler faster and create useable heat sooner with the same amount of energy.

Like most things in life there's a point where it becomes irrelevant.

If you're dealing with a small boiler like an EG30 there's little point of any in two risers especially if they're large. 

If I was piping my EG 40 now I'd use a single 3" instead of the two 2" that I did and honestly even that's overkill.