One pipe steam system problems

rsel04

My daughter recently moved into a house with a one pipe steam heating system. The downstairs has 3 radiators and upstairs has 4. The upstairs radiators don't look to be original. Anyway, There are 2 radiators downstairs and 1 upstair that are not heating up. I've checked the vents on the radiators and all were OK except 1 which I changed.

It looks like some of the piping was redone in the basement at the ends of the 2 mains to connect into the dry return. I also haven't found any venting on either the mains or the dry returns. Last winter I noticed that her basement was super warm so I put some insulation on the mains which helped.

As far as I can tell the boiler is piped correctly and will take some photos next time I visit.

My question is whether or not I should start by first installing some vents on the mains and take it from there? I have a 2 pipe Richardson system in my house and was able to solve a lot of my problems by adding a couple of big mouths on the mains but I have no experience with one pipe systems.

I've included some photos of where the mains tie back into the dry return. You can also see in one of the photos that there is a piece of a cut pipe sticking out of the wall. I'm guessing that's where the connection to the dry return used to be.

Any advice would be appreciated.

Thanks,

Rich

ethicalpaul

This looks like two mains. The problem that might be here is the drops from these mains do not go below the water line (seemingly).

When this occurs, you have no control over when or if one of the mains fills with steam so the radiators on that main might not get hot unless it's a real long call for heat.

Yes you also want to start with venting on each of these mains, and if possible, re-run the return so that it is "wet" (below the water line of the boiler) in this corner where the mains end.

If you can't do that, you can make a "false waterline" there, or you can match the venting of each main so that they naturally fill with steam at the same rate, but that is tricky.

After the main venting is sorted, there can be other reasons, most due to pipe pitch that can cause radiator(s) to not get heat, in addition to radiator venting which you seem to have a handle on, but one thing at a time.

Here is some info, or search "false waterline" on this site for probably more:

https://forum.heatinghelp.com/discussion/171067/a-false-water-line-is-a-true-solution-to-water-line-issues

rsel04

Thank you. This makes sense. I imagine steam is running straight into the dry return from the end of the mains.

Would adding a trap before the connection to the dry return help? That would act like a seal (instead of false water line) and prevent the steam from getting in but still allow the condensate to flow back to the boiler.

ethicalpaul

I think so, but honestly I would try adding the main venting first then you can see how the steam travels at that point. You can feel it traveling through the mains by gingerly touching it and see if one main heats up way earlier than the other one.

Others will have other ideas for you to consider too

Jamie Hall

A trap before the "dry return" would probably help — it would convert it into a real dry return, rather than what it is now, which is an extension of the steam main (I've ranted about this at some length, so I won't bother to now…). It isn't necessary, though, if the "dry returns" are NOT tied together above the water line at or near the boiler.

True dry returns can be, and usually are, tied together above the water line, and the main system vents are located there. Steam main extensions masquerading as dry returns must NOT be, and must be vented somewhere after the last radiator runout.

rsel04

Thank you Jamie.

So it seems the best approach other than repiping the returns would be venting the end of the mains and adding a trap to make it a true dry return is that accurate?

Jamie Hall

Yes.

rsel04

Follow up question. I was considering making these changes in steps. I wanted to first test this out on the main that has the union and would not require me to cut any pipes. The problem is if I put a trap at the end of main 1 only, I will still have steam coming in from main 2. My question is are there any bi-directional traps I can use so that steam will be blocked in both directions?

Danny Scully

@Jamie Hall , I beg you to stop this war you’re on to correct everyone from using the term “dry return” when referring to a 1-pipe system 🙏😉. Honestly, it’s doing more harm than good. Especially since there are charts in The Lost Art titled “Use This Chart To Check The Size Of One Pipe Dry Returns”.

What I would do is drop both of these mains individually to the floor, then back up to that larger horizontal return. You’re creating a water seal. Add drains to the portion of piping you drop to the floor. Add vents on each main, even if it’s off the vertical drop down. Just keep them as high as you can.

rsel04

“I beg you to stop this war you’re on to correct everyone from using the term “dry return” when referring to a 1-pipe system “🙏😉

not sure I follow your comment here. Aren’t you the one that mentioned dry return in quotes above? I was simply following your example and trying to continue on the approach of adding vents and traps which you seemed to think would help.

.

anyway, thank for taking the time to answer.

Best

Steamhead

https://forum.heatinghelp.com/discussion/comment/1811226#Comment_1811226

That won't work. The reason for the return is to carry condensate back to the boiler. This hookup would trap water in Main 1, causing banging.

First, add main vents. If this works well, the steam will reach the ends of both mains at about the same time, and little or no steam will get into the pipe between the mains. I've seen plenty of systems where this works well, even though it's not textbook.

How long are those mains, and what pipe size?

ethicalpaul

Danny was imploring Jamie about the term “dry return”.

Do what @Steamhead (and I) suggested. Just add venting and see how it does.

rsel04

thanks. Will give the vents a try and apologies that I misread the previous comment. Gotta stop using my phone for this stuff.

Best