One pipe steam - dry return loop under door?

Chuck_17

A one pipe steam system - dry return - can we loop it under (& over) a doorway?

It is a small building. The steam main goes across the building (sloping down) then the dry return goes back across the building before dropping down to the wet return.
The architect is adding an accessible route the length of the building to an elevator at the end - right where the return is.
So can the dry return loop down under a doorway (and up over), go back up before it hits the wet return.
(this is all in the building lowest level)

EdTheHeaterMan

I remember an illustration from a really old textbook that shows just that. Im sure one of the others here will confirm. I bet @DanHolohan has that book!

Ir might look something like this (but i t was not in color)

That old book might have pipe sizes and more detail. I'm sure there is a wrong way to do it.

DanHolohan

Yes, it's just like this. Substitute the beam for a door.

mattmia2

Or just drip it in to a wet return where it goes up and eliminate the bottom portion.

JUGHNE

This one is for return only.

This is after the end of main.

No steam line connected above.

The lower is wet return under the door.

The upper loop is to pass air back to the cond pump vent.
It also has a drip connected on the upper left.

Jamie Hall

Two things to be aware of: first, as implied in @EdTheHeaterMan 's drawing and made expllicity in @DanHolohan 's: the outlet pipe from your loop arrangement must be lower than the inlet pipe. Dan quotes in inch as a minimum; more is better. Which relates to the second: be aware that water will stand in the lower half of the loop at an elevation equal to the outlet pipe. Be sure that that is low enough so that there is no chance of flooding the "dry return".

Chuck_17

Thanks for the replies.

ethicalpaul

EdTheHeaterMan said:

I remember an illustration from a really old textbook that shows just that. Im sure one of the others here will confirm. I bet @DanHolohan has that book!

Ir might look something like this (but i t was not in color)

Hi Ed!

In your color picture above, why does a pipe even go over the door? I can't think of its purpose--it seems like it should drop to wet before the door and just run along the floor (where the pitch won't matter). Seems like you could save 6-7 fittings and a bunch of pipe.

mattmia2

If it is only a return I think you could do it with making sure there was venting on both sides (or even just a vacuum breaker if the return has nothing connected between the loop and the boiler). If it is part of the steam main supplying things beyond the loop, the upper portion is needed to carry steam.

EdTheHeaterMan

ethicalpaul said:

Hi Ed!

In your color picture above, why does a pipe even go over the door? I can't think of its purpose--it seems like it should drop to wet before the door and just run along the floor (where the pitch won't matter). Seems like you could save 6-7 fittings and a bunch of pipe.

If I were to change the diagram to this, would it make more sense?


I understand your point though. In a smaller home you might see this and I would suggest your idea:


But the OP did not offer dimensions and all I did was answer the query as asked!
And Dan H also agreed with his diagram. But you do bring up a good point Paul, there is more than one way to solve a problem.

Jamie Hall

ethicalpaul said:

EdTheHeaterMan said:

I remember an illustration from a really old textbook that shows just that. Im sure one of the others here will confirm. I bet @DanHolohan has that book!

Ir might look something like this (but i t was not in color)

Hi Ed!

In your color picture above, why does a pipe even go over the door? I can't think of its purpose--it seems like it should drop to wet before the door and just run along the floor (where the pitch won't matter). Seems like you could save 6-7 fittings and a bunch of pipe.

It could. Since this is not, in fact, a dry return, technically, but a steam main extension, it doesn't matter where it drops to form a wet return, so long as it is after the vent for that main and so long as there are no steam uses on it. @DanHolohan 's drawing must be used, though, if the pipe really is a dry return, or if it is a steam main with takeoffs beyond.

ethicalpaul

Thanks. I was taking the drawing at value-- with no takeoffs shown and no need for steam indicated