Piping Around Obstructions

New England SteamWorks

I saw this and started scratching my head. The boiler is immediately to the right (it's big, 32" waterline). The returns are wet, and are also clogged (which is the job here. Replace the wet returns).

But why the piping above the door and the vent? Unnecessary no? Or am I missing something?!

Jamie Hall

I have one of those, too, in one of the places I care for. I've never yet figured out what it's supposed to do...

Danny Scully

Hmmm...I’ve seen a diagram exactly the same but for above waterline piping, such as a steam main or runout...those dead mean always keep us on our toes.

New England SteamWorks

Deadmen did not do this one @Danny Scully . It was done about 20 years ago. I am thinking they saw the same diagram you saw for piping steam around obstructions and didn't realize they were piping condensate?

Fred

New England SteamWorks said:

Deadmen did not do this one @Danny Scully . It was done about 20 years ago. I am thinking they saw the same diagram you saw for piping steam around obstructions and didn't realize they were piping condensate?

That's what it looks like to me.

Pumpguy

This is referred to, oddly enough, as a DOOR LOOP, and is the piping arrangement used when piping around obstructions.

Water, or as we call it condensate, being heavy, falls to the bottom run to flow by gravity. Air, being lighter, flows through the upper part of the door loop.

The attached file explains in greater detail.

This is also illustrated and explained on Page 95 of The Lost Art of Steam Heating.

Fred

Pumpguy said:

This is referred to, oddly enough, as a DOOR LOOP, and is the piping arrangement used when piping around obstructions.

Water, or as we call it condensate, being heavy, falls to the bottom run to flow by gravity. Air, being lighter, flows through the upper part of the door loop.

The attached file explains in greater detail.

It would seem that a vent, either on the end of the Main or anywhere on the return, before it drops below the Boiler water level would take care of any air issues.

New England SteamWorks

So, being only condensate, what would happen if I remove the upper door loop? The condensate would still flow, right?

Pumpguy

Maybe so, unless maybe it was a 2 pipe vacuum return system?

I don't do steam piping, but when I see an arrangement like that, I immediately recognize it as a door loop.

Erin Holohan Haskell

Here's an article about piping past obstructions: https://heatinghelp.com/systems-help-center/piping-past-obstructions-in-one-pipe-steam-heating-systems/

New England SteamWorks

Exactly @Erin Holohan Haskell . Except that's for piping steam around obstructions. In this case, we are just piping condensate...

Pumpguy

The file I posted is for either steam or condensate flow. Only difference is the size and location of the pipes.

RayWohlfarth

@New England SteamWorks That is used to vent the air in the piping. If you did not have that, the air would not vent and flow would stop. Its a good thing to keep

Steamhead

But, if the boiler's water line is 32" off the floor in the pic, which makes this a wet return, the whole pipe is full of water so the loop over the door isn't needed.

New England SteamWorks

Steamhead said:

But, if the boiler's water line is 32" off the floor in the pic, which makes this a wet return, the whole pipe is full of water so the loop over the door isn't needed.

Right? That's what I think. Waste of time, energy, & material to put it back.

Mike_Sheppard

This is a wet return so that door loop is pointless. The diagram @Pumpguy posted is for a steam line and a DRY return. Both of which would be require to be piped like this. But being that this is a WET return, I don’t see how the loop above the door is needed.

STEVEusaPA

Looks like if you removed the pipe over the you would just have a second Hartford Loop. I wonder if it was put in initially because the returns were clogged, and they came up with this 'idea' because they saw it somewhere else.

Double D

I have a couple of Hoffman books that show that arrangement for looping a dry return around a door. I have seen it done on 1 pipe wet returns. The only difference is the drop went below the floor for wheelchair access from an elevator.

ratio

It might just be there to allow the wet return to prime. I have more experience with condensate drains, but a double trap will stop water flow without a doubt.

the_donut

Shouldn’t be a problem unless the wet return is emptied and line gets airlocked somehow.

EBEBRATT-Ed

@New England SteamWorks Is it possible that at one time the original boiler was in a pit that has since been filled and the water line is now raised making the loop not needed?

Fred

32" is probably a couples into those verticals. It is all water below. That loop over the door can not serve any purpose and that vent isn't venting anything. That is one vent that will never fail.

DanHolohan

If it's a gravity wet return, the upper pipe isn't necessary. But if the end of the condensate return goes to a vented receiver on a boiler-feed pump, the upper pipe would be there to allow system air to pass to the vented receiver.​

JUGHNE

I wonder if this was installed by a hot water heat guy who studied some steam piping and saw this setup in a book.

But he still had his HWH hat on most of the time and knew that any high point in piping could trap troublesome air in water lines and an auto vent would take care of it.

So he should get credit for studying piping diagrams and his workmanship looks good IMO.
Also get points as the dead man who sparked this post, thereby exposing more of us to the "over and under" steam piping.

New England SteamWorks

DanHolohan said:

If it's a gravity wet return, the upper pipe isn't necessary. But if the end of the condensate return goes to a vented receiver on a boiler-feed pump, the upper pipe would be there to allow system air to pass to the vented receiver.​

No vented receiver, no boiler feed pump. And there was never a pit.

I think @JUGHNE pretty much has it. It's not original Deadmen piping per owner. I think someone studied the "Steam Piping Past Obstructions" page and mis-applied.

Anyway, we'll all find out, because when I re-do the wet returns the door loop is gone...

Off I go!