Connecting Two Pipe Steam back to the boiler

mtarms

I have a two pipe steam system that has questionable near boiler piping. It doesn’t match the specs of the boiler manual and i’m getting a lot of water into the mains and then it’s pouring out of the air vent at the end of the returns near the boiler. I see how to re pipe the risers, header, equalizer and connect it to the main but i’m stuck on how the two dry returns combine and return to the boiler. The steam main and the dry return run parallel throughout the building and back to the boiler. I’m confused about if the two returns can combine right at the boiler, similar to how it is now or if it’s supposed to combine further away and only have one pipe connecting back to the boiler. And i don’t know what kind of main vents/traps i’m supposed to have and where to put them. Any help is appreciated.

Jamie Hall

I think you may have some comfusion regarding returns.

The high level returns — usually running close to the steam mains, are dry returns. They do carry condensate, but there isn't much of that, and air from the radiators. They must NOT be flooded, and the join together at the boiler and then drop to the floor level or near it.

The low level returns — usually at or near floor level — are below the boiler water line, and are always flooded. They are called wet returns for that reason. They carry condensate from any steam piping or dry returns which are pitched away from the boiler.

In your pictures I do not see any wet returns at all — so everything else is pitched back to the boiler (or should be!). If you are getting water building up at the ends of the steam mains or dry returns, they are pitched the wrong way.

Unless, that is, some bright individual in tidying up the basement removed the wet returns which should have been there to take drips from the steam mains and dry returns…

Now there is another problem: the near boiler piping is rather badly wrong. No header, only one riser, no real equalizer.

EBEBRATT-Ed

Has this boiler ever been skimmed?. It looks to me that the near boiler piping although far from textbook should work. My only question is if one or two risers are required for that size boiler. Check The boiler manual

How is the boiler water level when it is steaming? Violent fluctuations of the water level? Or steady water level meaning gentle movements not exceeding 1" up and down

Steamhead

That near-boiler piping will never work right. For starters, there is no header. Then, the riser from the boiler looks like 2-inch, and there is only one riser where there should be two. The result is water is getting up in the steam mains, causing the problems you cite.

This boiler has the name Lennox, but is a re-branded Dunkirk. Dunkirks are extremely sensitive to improper piping.

It needs to be properly repiped. Period.

mtarms

The company that installed it in the early 2000s piped it this way. I’ve been trying to figure out how to fix it. I need to get it right so i can insulate the pipes. I understand how to do the risers, headers, and main. I don’t understand how the two return lines are supposed to connect back to the boiler and where the vents/traps are supposed to go. I don’t want to start until i have it planned out. When the boiler fires it, hammers mid cycle, gets low water, adds water, then pours water in the floor out of the brass hoffman vent pictured. That is why there is rust stains on the floor.The silver vent never seems to do anything. I don’t even know if it’s a vent. And yes it’s been skimmed several times. And I replaced every valve and steam trap when i moved in and that helped but now i’m trying to get this piping right.

Jamie Hall

OK. That first picture from the manual posted here shows the minimum near boiler piping needed. The thing which is a little confusing is that you have the outer end of the steam main right at the boiler, which is a bit odd but not a problem.

The silver vent is the main vent for the steam mains. What should happen is that eventually it should get hot and close. If steam takes a long time to get there, it may be failed shut In any event, I'd replace it with a Gorton #2.

The brass Hoffman vent is the vent for the dry returns from the radiator steam traps which are coming in there. It's probably fine.

Both of those pipes then go into vertical pipes, called drips. They meet together below the water line, which is fine, It looks to me as though there is another return dry return in addition to the one you have marked. That should be tied together with the one you did mark more or less where the Hoffman vent is.

The line which drops down vertically from that to the loop of pipe attached to the boiler is going to go away.

Then you need to build that bit of piping called the Hartford Loop in the diagram, just as it is shown. It looks as though someone tried to make a Hartford Loop — but the return pipe needs to go into the leg of the loop which does not attach directly to the boiler, rather than to the one which does.

Now you need to pay attention to the header piping. Arrange it exactly as the diagram shows. Two risers going up — one from each side of the boiler — at least two feet. Then going over horizontal another foot or so, and both connecting to the horizontal pipe as shown. That header should have a very slight slope down to the right. Then connect your steam main in beyond where the two risers join the header. Then go a bit farther and take a vertical pipe, called the equalizer, down to that Hartford Loop.

It really isn't hard if you follow that diagram as exactly as you can. Pay attention to the pipe sizes and any dimensions shown.

Better yet. Where are you located? We just might know someone nearby who could do all that for you in less than a day…

mtarms

Thank you. All that was helpful. I’m in East Tennessee and haven’t found anyone that actually knows steam.

mtarms

It’s just the two return lines. You may be seeing the weird way they did the equalizer or the gas line. Can i swap out the 90 at the bottom of this return line in the diagram for a T and connect my 2 return lines that way? Then put the vents on 6-10 inch stub before it turns down to go into the hardford loop? The vents are close to my floor joists currently and the steam is rotting them. Is it acceptable to step the return lines down maybe a foot lower a little bit away from the boiler, so i have head room to put the vents up on a stub like it suggests? Also, is the reason i don’t need an F&T trap because the steam main circles all the way back to the boiler as a dry return instead of stopping at the last radiator?

Jamie Hall

All that should be OK.. You don't need a trap the way yours is laid out. The steam in the steam main is separated from the dry return by the water at the bottom of the vertical pipes.