End of steam supply connects directly to return?

mtriplett

I live in a house built in the 1920's and its heated via steam. It has main supply lines, a dry return, and a wet return (or used to be a wet return as it sits below the boiler water level). One of the things that I don't understand is why the main supply (seen as the pipe on the right in both pictures attached) directly connects to the return (seen as the pipe on the left) just before going under the concrete without any sort of trap or valve. I find that steam travels down and up the return. Can anyone explain this? Thanks!

JStar

Has anything changed recently? New boiler?

The old boiler was likely taller and the waterline would have covered those tee connections, acting like a trap. If that connection is now exposed (above water line), you'll need to add a trap to the end of the main. There are special considerations for this, but it can likely be done.

Can you measure the water line compared to these fittings?

Danny Scully

It’s a 2-pipe system with a crossover trap above. It doesn’t appear to be high enough to cause any unwanted crossover, but looks can be deceiving. Have you confirmed the crossover trap is operational?

Jamie Hall

Seems to me it could be either @JStar 's explanation or @Danny Scully 's.

Monitor the system very closely as it is heating up -- not once it's hot. The steam main should get hot and the inlet to the crossover trap should get hot. The outlet from the crossover trap should not get hot, at least not as a sort of continuous flow (if that makes sense). If it does, the crossover trap may be failed open. If it is, just repair it. Similarly, the drip from the steam main may get very warm (shouldn't be steam hot) but the drip from the dry return should not get even warm, never mind hot. If it does, that water seal is not functioning.

You do say that they join into a what is a "wet return, or used to be". Do I take it that there may be some uncertainty a to whether it is still below the water level, as @JStar suggested? If so, use a laser level or water level from the boiler to verify that it is still below the water line -- by several inches.

JUGHNE

I have never seen a cross over trap in the wild.
But from here I have learned that it is to vent the air out of the steam main and put it into a dry return. This looks to be a wet return so where would the air go??

If we had a picture from the side of the top of these two pipes then it might help me understand how this might work.

Jamie Hall

JUGHNE said:

I have never seen a cross over trap in the wild.
But from here I have learned that it is to vent the air out of the steam main and put it into a dry return. This looks to be a wet return so where would the air go??

If we had a picture from the side of the top of these two pipes then it might help me understand how this might work.

That dry return most likely goes back to the boiler, and that's where the system air vents are. Come visit Cedric someday, and I can show you!

JUGHNE

So if the dry return is sloped down back to the boiler do we need the connection to the wet return?
The condensate would drain back towards the boiler and the air would head to the air venting at the boiler.

JStar

It's odd to see a cross over trap go to a dry then wet return before any air vent. No way for air to get out. Are there vents nearby on the return? Is there a condensate tank?

Jamie Hall

Many vapour system -- and perhaps some regular two pipe systems -- were arranged with the steam mains parallel flow and the dry returns running beside them counterflow, with crossover traps. This may be one of them. In these, the condensate from the steam main dripped into the wet return at the end, while the air went through the crossover trap into the dry return. In the dry return, the condensate from the radiators also flowed to the distant end, while the air from the radiators and the steam main crossover trap flowed the other way, back to the boiler, where the vent or vents were located. This arrangement kept the dry return and the steam main at very nearly the same elevation -- useful for long mains -- and concentrated the vents and any esoteric hardware (like the dreaded Hoffman Differential Loop!) at the boiler, where they could be at least noticed.

clammy

Looks like that was a loop seal ,sealing steam from the steam main from getting into the return , being both drop down and tie together below the boiler water line forming a loop seal . Are sure that cross over trap is original ,I have seen this set up with out a cross over trap but instead they used Hoffmann vapor vacuumed vent #67 . Being both dry and supply drips go underground where is your system vent.? If there is none then get rid of the crossover and install 2 good main vents If your steam main is pushing steam back up the dry return you may have lost the original boilers higher water line and have no seal in which case you ll need to install a false water line . Have you checked what pressure the boiler is operating at with that type of system you would be in better shape using a vaporstat instead of a pressure-troll . Peace and good luck clammy

JUGHNE

Jamie, that counterflow return was my next question.....only because I have studied the only 2 pipe counter flow system I have ever heard of, it is 2 blocks away from my house.......and I can see the advantage about head room in the basement.

So if a new crossover trap element does not fix this because of the possible new higher water line of the boiler, would the Gifford Loop at the boiler correct the water loop seal at the drops under the crossover trap?

Jamie Hall

JUGHNE said:

Jamie, that counterflow return was my next question.....only because I have studied the only 2 pipe counter flow system I have ever heard of, it is 2 blocks away from my house.......and I can see the advantage about head room in the basement.

So if a new crossover trap element does not fix this because of the possible new higher water line of the boiler, would the Gifford Loop at the boiler correct the water loop seal at the drops under the crossover trap?

Hadn't thought of that! Good call -- it might very well be just enough.

mtriplett

Thanks all. The house was built in 1924 by a member of the Crane plumbing/elevator family. I believe it had many different boilers starting with coal as I have a coal room still having coal in it. The current boiler was installed in 2009, just a few years before we moved in. Someone above was correct in that there are 2 main supplies that run along the house (70ft or more each in length) and dry returns that run alongside. There are a total of 2 "wet" returns that also run the length on the home and 2 additional wet returns that tie into those wet returns (one due to stairs and radios being on a middle tier and the other one is show in the pictures above - that is at the other end of the house in the boiler room itself). That might make sense that those loops were meant to seal steam off from entering the returns, but the water line isn't that high today and steam gets into the returns. The radiators still work, but maybe they would work better had the steam not entered in the first place. I posted 2 more pictures below. You can see one of the wet returns on the left side of the boiler (again there are 3 total returns that make their way into that one return coming out of the concrete). The other picture shows a little of the condensate tank/pump but it also shows another wet return coming out of the concrete and the vertical pipe on the right connects into the wet returns. All of those returns go into a condensate tank with a vent. But the hole on the 8G trap is small and while the system vents, I'm wondering if vents need to be placed on the dry return as now it runs directly into the wet returns. With that information, any different thoughts?

Jamie Hall

Unless you can get the water line up to where it belongs, you are going to continue to have problems. Wet returns -- at or near the floor level -- must be wet for their full length, and at least a few inches up on every drip that connects to them. There are no alternatives. What you may be able to do, however, is install a false water line since raising the boiler so that the water line is where it should be may be difficult. That boiler's water line is at least a foot -- probably more like two feet -- too low. The condensate tank isn't helping at all -- in fact, if the wet returns drop into that that is what is controlling.

dopey27177

You have a master steam trap on what looks like your wet return this a no no. additionally you have a boiler feed pump as part of your system.

You need to go to the ends of your steam main and restore the the crossover traps to vent the air from the steam mains and then remove the master steam trap. When that trap closes steam will go across the entire wet return and dry return system.

Make sure you have a vent pipe on the tank of the boiler feed pump because that is your main air vent, The tank needs to be open to the atmosphere,

Jake

clammy

From the looks of your boiler piping it doesn’t look like you have a proper swing joint. Looking at the picture it would seem you could pipe a false water line and have a water seal again ,I really dont think you need a condensate pump at all . Do you have separate dry returns that end in the boiler room or do they just drop and tie together w your end of the main drips . Either way you may need to restore cross over traps to the system and add steam main and dry return venting . Making a false water line is no big deal and in the long or short of it cost much less and doesn’t need to be replaced or repaired years later no moving parts simple . It s a tool some are afraid to use in a lot of cases don’t know about or quite understand .peace and good luck clammy

mtriplett

Thanks again. So, I have 4 termination points like the one in the picture at the very top. According to what I am reading here, I think, it sounds like I can put a trap between the steam mains and returns where they are now tied together just before going underground. This will keep the steam out of the returns. As for the dry returns, they are tied into the wet (that vertical pipe in the picture) and all feed into a vented condensate pump through the 8G trap in the picture. Do I need to vent that more? If so, what kind of vent are we talking about and where would it get placed? Also, some say to vent the steam mains - currently, they get vented to the dry returns...do I need to vent them further? If so, then what kind of vent are we talking about and would it be placed at the ends of the mains? I really appreciate it.

JStar

Installing a false water line would negate the need for adding all those traps. Much simpler, and no long term maintenance costs. Still need to establish where the main air vents are though.

mtriplett

Thanks Jstar. The mains vent through traps into the dry return and out of the vented condensate pump. There are no other main vents. Interesting too because the steam moves through the mains at a blistering speed.

JStar

The vent on the condensate pump is a great way to get rid of air. Unfortunately, if you have a FWL installed, you'll need another way to vent the system. The original system likely had one air vent near the boiler, or individual vents at the ends of the dry returns. Somewhere along the way, the system was modified and lost those features. Could be a neat project to get it back to near original function.

Jamie Hall

As @JStar said, originally this system probably had one or more main vents at the boiler, where the dry returns turned down to the wet return. Condensate was taken by the wet return. At some point some bright child put in the condensate tank, and your water lines got messed up. It would be a really neat project to study and put back to original function -- and I dare say it would work better, too.

mtriplett

Thanks again all. I've learned a lot. One more question - if a vent(s) is put where the dry returns turn down to the wet return, does such a vent also allow air into the system like an open system? I.e., I know vents allow air out, but do they also let air in? and is that enough to let condensate flow out of the system properly without air lock?

JStar

Yes, non-vacuum vents will allow air back in.

mtriplett

Getting back on here. Does anyone know of a person/company that has experience with false water lines/boiler systems in the western suburbs of Chicago? Any thoughts would be greatly appreciated. Thanks.

Steamhead

Call @The Steam Whisperer .

Neild5

I use The Steam Whisperer, Dave and his guys are great.  He will be replacing the boiler in the condo building,  because it is controlled by a board I needed multiple bids, his was the only one that had options and the only one that actually considered the radiation load in the building.   Each company was given a spread sheet listing all the radiators, the current boiler is about 40% oversized and one company actually quoted going 15% larger than we have.