Welcome! Here are the website rules, as well as some tips for using this forum.
Need to contact us? Visit https://heatinghelp.com/contact-us/.
Click here to Find a Contractor in your area.

Two-Pipe Steam Heat System - gurgling on 1st floor radiator

Some Background - I have a two pipe steam system on a home (built 1916) I purchased 23 years ago. After being in the house for 2 months, I needed a new furnace (now I call a boiler - Thank you "We Got Steam Heat, by Dan Holohan). I bought a new boiler from Sears and had Sears technicians install it. The technician who installed it was screaming and swearing an I got the impression he did not know what he was doing - I was right. A year later I had a high velocity air conditioning system installed and one of the individuals checking the new air conditioning system ( a former Navy Seal) noticed the piping on my boiler was incorrect and asked if I had "water hammer" problems. My answer was yes and it was so bad that it cracked the plaster in my living room. I still had a warranty with Sears so I called them. They sent a couple of guys out how informed my that the system was completely installed wrong and they would correct it at there expense. A week later (in July) a couple of guys showed up in vans and spent the next three days cutting and installing black cast iron piping. They were calm and collected and really seamed to know what they were doing. They informed me that my system needed a Hartford loop which was missing along with the fact that the piping coming out of the top of the boiler was completely wrong - they showed me the drawing in the manual that depicted the "wrong way" to pipe the system - this was the way the new boiler had been installed. They also told me that my warranty covered only the furnace system area (I did not pay much attention to this at the time). They left and told me the system was working very well but I should get the rest of the piping system evaluated by a professional. I called Sears to have them check the rest of the system and I also purchased a annual servicing and cleaning with them. That winter everything seemed to work great - no water hammer anymore; however, not all the radiators seemed to work, but the rooms seemed warm enough. 22 years later I decided that I really wanted to understand this steam system and I really wanted to to get all the radiators working properly. Over the years that led up to this point, I noticed that some of the vents on my radiators had steam constantly coming out of them, along with these large vents on the pipes in the basement on the main steam lines. I had asked the Sears technician cleaning my system if this was all OK and he said "yes - it is a steam system" I recently purchased two of Dan Holohan's books and began to read and acquire a general understanding on how my system worked. I noticed that two pipe systems probably should not have vents on the radiators. I also notices that the vents (Hoffman 75s) on the main pipes (all three) should not be leaking steam all the time: they should shut when the steam hits them. I did what I could to fix what I perceived to be the little problems (new Hoffman 75s), new radiator vents (may not need these), cleaned the watch glass tube and pigtail tubing (amazingly dirty and plugged even after a recent visit from Sears technician). System seems to be working well with a few exceptions.

My Problem - on the far end of the house where a branch of the main steam line runs to three radiators , two on the first floor and then a T in the line where a line runs up to a second floor radiator ( which seems to be the end of the line). A return drain line leads out from each of these radiators and returns back to the boiler. The radiators have new 3/4 inch steam valves, original Broomell "PAT D" elbow traps (?), all of which I have cleaned and put back (I did not have trouble removing them). The radiators seem clean inside and there is no accumulation in the bottom, All of the d return condensate lines all pitch downward away from the radiators and back to the boiler (no sags) allowing water to flow by gravity. The steam lines also pitch away from the radiators and slope back toward the boiler.

The first floor radiator and the second floor radiator (directly above the first floor radiator that is not working) are both cold unless I really crank the heat up (78 F) and leave the system on for some time. Then the second floor radiator heat properly; however, the first floor radiator has a gurgling sound and the first area that gets warm (hot) is the return connection (by the Broomell "PAT D" elbow). It seems water from the condensate line is pushing into this area and this lower corner of the radiator gets hot. The gurgling gets very loud and I can tell there is water in the pipe (condensate line). The steam line never gets hot in the riser along the side of the radiator so it seems that steam is not making its way into the radiator. Additionally, the vent on the radiator is constantly leaking air (not steam). When I turn the steam valve off, the gurgling continues and coll air continues to push out of the radiator vent. Note that the second radiator on the first floor that seems to be part of this section of the heating system seems to be working properly.

I have become very interested in the steam system and would like to understand what the problem is - I suspect it may have something to do with the Broomell elbows and perhaps they need to be replaced with a thermostatic steam trap??? Any help on this would be greatly appreciated - I have a great admiration for guys that work on these systems, but I am aware it can take some time to accumulate the knowledge to fix some of these problems. I would like to do it myself, but understand the need to get a professional in. I have found a professional that was highly recommended as a steam expert as a default if there is nothing I can do.


  • Jamie Hall
    Jamie Hall Member Posts: 22,912
    Oh boy. Broomell systems work splendidly. On low pressure. On anything more than a few ounces, they work poorly -- if at all -- as steam will happily blow by the return elbows and pressurize the returns. Which is what you are seeing in those problem radiators.

    Further, they do not need -- or want -- vents on the radiators. They do need at least adequate main venting -- on the dry returns.

    So... first step is to make sure that your system pressure is low and stays that way; you will need a vapourstat (and should have a low pressure gauge) set to cut out at no more than 8 ounces per square inch. It can cut back in at around 4 ounces.

    Second step is going to be ensuring that you have adequate venting on the dry returns -- usually at the boiler, where they turn down to connect with the wet returns.

    At this point you can take the vents off the radiators. They don't belong, and they will only complicate matters.

    Next thing to do is to examine the steam mains and determine if there are crossover traps connecting them to the dry returns. There may or may not be. If there are, and they are working properly, nothing more is needed in that regard. If there are not, then generous main venting is needed at the ends of the steam mains. That will help even out steam delivery to the system.

    One other thing on steam mains -- are they insulated? If not, they need to be...

    Do you have a copy of The Lost Art of Steam Heating? You should. There is a good writeup in there on Broomell systems which will help you -- as well as a wealth of general knowledge.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • ethicalpaul
    ethicalpaul Member Posts: 5,585
    That’s a great story, I’m so glad you found the second crew and that Sears honored the work
    NJ Steam Homeowner. See my sight glass boiler videos: https://bit.ly/3sZW1el