1 or 2 raisers?

ethicalpaul

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.

Well I mean you can't avoid having an elbow from the header down to the equalizer so it's not really a question.

But the elbows at the tops of the risers could be skipped with the risers running directly into the header (and we sometimes see that), and so that's why I think of those as the swing joints that people are always saying are so necessary.

EBEBRATT-Ed

ChrisJ

https://forum.heatinghelp.com/discussion/comment/1901794#Comment_1901794

Everyone, you left him speechless.

Sigh……

JUGHNE

So just to confuse myself and possibly others, what about the consideration of the internal surface area of the ID of the pipe itself?

The pipe does in effect act as a condenser (think radiator EDR) and the more surface would cause more condensation of the steam.

Without crunching numbers, it seems that two 2" risers of 24" height would have more ID area than one 3" X 24" riser.

So what does anyone think?

EBEBRATT-Ed

2 2”is 6.2 square inches

1 3” is 7”

@JUGHNE it would seem that way but the math says otherwise

mattmia2

https://forum.heatinghelp.com/discussion/comment/1901805#Comment_1901805

I think he is talking about the surface area of the cylinder, not the open area of the circle, although they are pretty close, 2x2" has just slighly more interior surface area than 3", assuming i'm using actual 2" and 3" id sizes instead of the nominal sizes.

edit:
i used google's calculator for the area of a cylinder and it included the ends which is why it was wrong.

ChrisJ

https://forum.heatinghelp.com/discussion/comment/1901805#Comment_1901805

For what @JUGHNE is talking about we need to use circumference.

Two 2's is 12.57"

A single 3" is 9.42"

So a single 3 has less surface area and less heatloss. It probably would never matter especially insulated.

But, technically…..

EBEBRATT-Ed

IDK. The size of the hole(s) is what the steam goes through.

ChrisJ

https://forum.heatinghelp.com/discussion/comment/1901837#Comment_1901837

It is.

But he's talking about heat loss of the piping and how much it initially absorbs to bring it up to temperature.

Two 2" pipes has more surface area and probably mass than a single 3"

A single 3" flows better and has less loss.

ethicalpaul

https://forum.heatinghelp.com/discussion/comment/1901803#Comment_1901803

I think this issue is mostly unimportant and not noticeable—we can't say that pipes don't make good radiators and then claim that uninsulated pipes cause tons of condensate. They can't both be true, pick a side 😅

But the thing to look at is the surface area vs the interior flow area.

Yes a small pipe has less surface area for heat loss, but it can carry much less steam. A large pipe although it has a greater surface area, it has a MUCH greater capacity to carry steam, so the ratio is more favorable.