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One pipe main vents needed?

pmchalepmchale Posts: 19Member
I have a one-pipe system with mostly the original piping, which appears to have no main line(s) vents. The only venting is at the radiators. The system is not well balanced (very little steam to the two upstairs radiators on the bad side, which put out air, but never get much heat to them before the system kicks off after thermostat hits 68 degree top temp), and I am thinking that I could possibly remedy that with some venting on the side that does not get adequate heat to the radiators. My first question I looking at some re-piping to add a basement vent or two, or is it possible to tap into the existing pipes? I have Dan's book and am doing some research, am hoping to find a solution. Other than poor balancing, the system works fine. Boiler is only about 10 years old. All radiator vents are working fine.


  • KC_JonesKC_Jones Posts: 3,511Member
    Pictures of your mains, specifically the area where the main ends and turns down to wet returns and the area around the last radiator take off from the main(s).

    We could give good advice on main vent location and what could be involved to add it with those pictures.
    2014 Weil Mclain EG-40
    EcoSteam ES-20 Advanced Boiler Control
    Boiler pictures updated 2/21/15
  • pmchalepmchale Posts: 19Member
    Can do, stay tuned, and thanks.
  • FredFred Posts: 6,579Member
    edited January 9
    While you are taking those pictures, look around those areas and see if there are any tappings, on the main, that have plugs in them. Someone may have taken a bad vent off and just plugged the opening. Also, tell us how long each main is. That will help determine how much venting is needed and remember you need vents on each main, even the one that you consider "Ok" as it relates to heating the radiators.
  • Circa1902Circa1902 Posts: 20Member
    Your situation sounds very similar to mine, which I'm still currently working on. It was common for older coal systems to have no, or inadequate, main venting.

    If you need a quick fix, I had good luck with Heat Timer Varivalve quick vents on my coldest radiators. These vents vent air about as fast as the 1/8" tapping on your radiator will allow. This will allow more/fasting venting of the the lines and radiators and should help those rads get warm at least part way across.

    I am using a bunch of Varivalves right now in my system to help figure out how to balance the radiators in different rooms (easy to adjust). Once it's better balanced I plan on replacing with Gortons of appropriate size.

    To answer your question it is possible to tap into the existing pipe, but also not much more work to simply add a tee and union to the appropriate place on the main. That would be the proper fix.
  • BobCBobC Posts: 4,808Member
    Using those vents on a radiator can be problematic.

    If you vent a radiator too fast the steam can shoot across the radiator and close the vent before heating the radiator fully. Also they will not close if water hits them because they don't have floats to block water.

    A steam main could be drilled and tapped but you would be best drilling on top of the main so you don't risk getting water in the vents.

    Smith G8-3 with EZ Gas @ 90,000 BTU, Single pipe steam
    Vaporstat with a 12oz cut-out and 4oz cut-in
    3PSI gauge
  • FredFred Posts: 6,579Member
    ^ What @BobC said!
  • nicholas bonham-carternicholas bonham-carter Posts: 7,283Member
    Radiator vents cannot do the main job of air removal. Main vents of generous size are essential for economy, comfort, and heating response. The radiator vents should not be too fast, so as not to allow the steam to arrive at one of the nearest radiators, before the last on the line. Otherwise you will have an unbalanced asystem with some rooms hotter than others, and heaven forbid that room should have the thermostat in it!
    The main vents could possibly be mounted on the vertical pipe dropping down to the wet return, if the ceiling is in the way, but we would have to see a picture of that location.—NBC
  • pmchalepmchale Posts: 19Member
    I have included several photos, a couple of the main that feeds the side getting much less steam, and many near boiler piping photos. Hopefully you can open them for viewing, if not, I would be happy to send them via email message. From the research I have done so far, it seems like there should be a main vent at the T at the end of the main, which feeds the four radiators that are not getting proper steam...but that is just my guess(?).

  • pmchalepmchale Posts: 19Member
    I will measure the length of the mains, before T's. I have looked for plugged former vent holes, but have not found any yet. I will look a little harder to make sure that main vents were not simply removed, and could easily be replaced. I will supply main lengths and then welcome further advice.
  • Paul48Paul48 Posts: 4,492Member
    You really need to get a steam pro in there to evaluate your system. The picture are a maze of unrelated pipes on here. It would be like car isn't running right, and here's my problem. Then showing a picture of the engine.
  • pmchalepmchale Posts: 19Member
    I agree about the steam pro, but they seem to be hard to find around here (Syracuse, NY). I have contacted a well reviewed company, but have not heard back. But I am not sure the deal with steam systems. Hopefully I will hear from them.
  • Paul48Paul48 Posts: 4,492Member
    There's many times that we can get a complete picture of a homeowners system, with a few pictures. But, their systems, as a whole, can be seen. Hopefully, any issues you have will be small, and I'm not trying to be rude. Upstate tends to be a tough area for finding steam contractors. Downstate is not much better. The city and the area around the city, has great resources. I know...that doesn't help you.
  • pmchalepmchale Posts: 19Member
    Oh, no offense taken! Hopefully I can find someone, or work this out somehow. Definitely and interesting mystery to solve.
  • Gary SmithGary Smith Posts: 152Member
    Do the steam mains slope back toward the boiler, or do they slope from the boiler so the most distant point of the mains are the lowest points. It's hard to tell from the pictures. When you send the length and size of the steam mains, could you also send photos of the ends of the steam mains.
  • FredFred Posts: 6,579Member
    You need vents, for sure but I also think I see two or three locations where the steam main branches off in different directions with Bull headed Tees (Main hits the backside of the Tee). With that configuration, the steam hits that backside and pushes back as it tries to make a turn and go in opposing directions. That is not helping your situation either. Get the vents on, that will help but as has been said, a Pro, on site can best evaluate what needs to be done to optimize the system.
  • pmchalepmchale Posts: 19Member
    The mains slope back to the boiler. I assume that was asked to make sure that the condensate can flow back "downhill". Secondly, instead of Tees, what should be there, to split the main to go in opposite directions...I can think of a 45 Tee, followed by another 45 Tee...? That said, I also noticed, after reading more about one-pipe systems, that my risers off the mains really should be at 45 degrees, not 90 degrees, as they are in the problem areas. That might also slow the stream down, correct?
    I did have a contractor respond, and will call me tomorrow. Still not sure if he does steam systems or not, but he did not state that he didn't. We'll see.
  • Gary SmithGary Smith Posts: 152Member
    Ok, you indicated your basic problem was a few radiators on the upper levels did not heat well. Your original post did not indicate that you were having hammering or noise problems. So, a few common causes of poor heating radiators with no hammering or noise are:
    1. No main vents or too small main vents. Ask your responding contractor, or check yourself, to see if there are vent near the ends of your steam mains in the basement.
    2. Boiler pressuretrol is set at too high a pressure and shuts off boiler. For most systems using Honeywell pressuretrols (grey box on boiler) the settings are 0.5 on the outside metal tab and the dial on the inside set to "1".
    3. Radiator vents on the radiators that ARE heating are too large (fast) and these radiators are "stealing" steam from the others.
    4. Radiator vents on the radiators that ARE NOT heating are too small (slow to release the air).

    Adding main vents if you do not have them or increasing their size will help greatly, and do check the pressuretrol settings and that the pigtail below the pressuretrol is not clogged with "gunk" (be sure to have the boiler turned off when you take the pressuretrol and /or pigtail off. After that you can move on to adjusting the individual radiator vents. I have found that adjustable rad vents like the Hoffman 1A or Ventrite #1 are very helpful in this regard because they are easily adjustable with a dial. If you have Heatimer Varivalve vents (see for a picture) on your radiators, most likely on the radiators that heat fully, these vents are very fast and will often cause balancing issues by letting all steam go to the rads with these vents and no or little steam going to the other rads.

    so, first of all, do you have any vents on or near the ends of your steam mains?
  • Paul48Paul48 Posts: 4,492Member
    If there are enough radiators to warrant it, you run another main. If not you extend the one single main. You don't tee the main and run off in 2 different directions. Even with arrows on the pipes, the steam still doesn't know which way to go...JK
  • pmchalepmchale Posts: 19Member
    To clarify, the problem radiators are all off the same main, four radiators total. The ones on the first floor get decent heat, but the two on the upper floor do not (each is on a opposite leg of the main, after it Tees. There are definitely no vents on the mains, anywhere in the system. I have Hoffman 1A vents, and most are newer (last 10 years). I will check the pressuretrol settings and understand what that is/does. I will also measure main lengths as suggested and include a rough piping schematic tomorrow.
    Thanks much.
  • pmchalepmchale Posts: 19Member
    Hoffman vents on the first floor are at lower settings (smaller vent hole) than the ones on the upper floors (6- bigger vent hole).
  • Gary SmithGary Smith Posts: 152Member
    It also matters if there are main vents on the other mains or main branches and what the radiator vents off the other mains are set to vent at. What happens as is often said on this Wall is that the steam takes the path of least resistance and so if the other radiators (on the same or on other mains) offer less resistance than the radiators and vents that do not heat, then all or most of the steam goes there--to the places that offer the least resistance to steam flow.

    Main vents help A LOT , to even out the steam distribution. It really helps to vent the steam mains fast (get steam to all parts of all steam mains) and vent the radiators more slowly, but proportionately to the heat output needed (slow down venting in warm rooms, speed up venting in cold rooms), but this is only really achievable if you have good main venting and proper boiler pressure control (settings on pressuretrol and clean pigtail).
  • FredFred Posts: 6,579Member
    As I said, getting main vents on the system will help a lot. Once you do that, you can determine if other work needs to be done or if piping may be able to wait until the boiler has to be replaced. Steam will take the path of least resistance and all the mains need to be vents so that they all fill with steam at about the same time or as close as possible.
    When you branch off of a main, a Tee can be used but it should be turned to allow the main to make turns rather than slam against the back of the Tee.
    I'm fairly sure once you get vents on the main where the radiators don't heat, you will see improvement but you need to vent the other main so that it doesn't become the problem main.
  • pmchalepmchale Posts: 19Member
    This all makes complete sense, and is also what I have been researching in "The Lost Art of Steam Heat". The radiators on the main that heat the best (both on the first and 2nd floors off the same main) are on the largest diameter main, so least resistance. I do not intend to do the work myself, although it would be interesting...but that said, we are probably talking about main vents like the Gorton #1, correct? Mine is not a huge house, and the mains are about 20 feet or less.
  • Gary SmithGary Smith Posts: 152Member
    Gorton #1 or Gorton #2 or better yet a Barnes & Jones Big Mouth vent on the end of each main would be appropriate for small diameter (2-3") mains 20 to 30 feet long. Those will get the steam to the main ends quickly. Big Mouths are available on this site or from Amazon (when they have them in stock) and are less expensive, or nearly the same $'s, and faster venting than the Gorton's, but all are fine vents. Be sure to mount the vent several inches above the top of the main, near the end, preferably AFTER the last radiator pipe leaves the main. If there is no convenient place to mount a vent you or your contractor can install a "service saddle" , like Romac Industries Model 101U, (costs less than about $50- other brands will work as well, Smith-Blair, JCM, etc), but be sure to order the EPDM gasket, not the rubber gaskets. Rubber is not good for steam temperatures, EPDM will work up to about 350 deg F. These are available with 3/4" threaded outlets and are very simply installed by drilling an appropriate size hole in the pipe and clamping the saddle over the hole. Or, for a really permanent installation, have your contractor install a T with appropriate side outlet near the end of the steam main.
  • FredFred Posts: 6,579Member
    I would go with the Big Mouth, if it were me. The Gorton #1 is probably marginal capacity. The Gorton #2 is fine but costs as much as the Big Mouth and the Big Mouth has almost twice the venting capacity, is solid brass and very reliable.
  • pmchalepmchale Posts: 19Member
    Roger, thanks.
  • mikeg2015mikeg2015 Posts: 377Member
    Did you say the mains slope back to the boiler? Or away from the boiler. That makes a big difference.

    Try and map out your system to see which type it is.
  • FredFred Posts: 6,579Member
    edited January 11
    From the pictures, it looks like a counter flow (mains pitch back towards the boiler with a drip on each main, at the boiler. Vents still go on the end of the Mains, furthest from the boiler, after the last radiator run-out.
  • pmchalepmchale Posts: 19Member
    To mikeg2015 - I put the level on a main or two, as well as pipes coming off the mains, feeding radiators, and yes, all slope downhill toward the boiler.

    For anyone else paying attention, I will attach a system piping (basement) schematic shortly.
  • pmchalepmchale Posts: 19Member
    I am attaching a schematic of the basic piping layout for my one-pipe system. I noted the radiators with low/no heat and the ones that get the most/quickest heat. I forgot to asterisk the other two bathrooms, that also get low heat. In the drawing, they are below the boiler (at the bottom of the sheet). These are fed with a smaller diameter pipe (1 or 1.25"). I am guessing as an add-on, long ago, when bathrooms were added, when indoor plumbing came around (?).

    Pipe lengths are noted, as well as pipe diameters, in parentheses.

    After reading some of the responses to my posts, and doing some research in "The Lost Art of Steam Heating", I can clearly see that the piping setup is not extremely efficient to get steam to all radiators equally. I definitely have some ideas on how to do a little re-piping between a couple mains and the radiators they feed, but I would certainly hire a pro for that.
  • Gary SmithGary Smith Posts: 152Member
    The schematic is a good start, suggest adding pipe lengths and EDR of each radiator served (which you can get from LAOSH if i remember correctly). If all pipes have proper slope and are not too mis-sized for the radiators served, there is no reason you should not be able to get better balanced heating if you install good main vents on all the steam mains and then balance the radiator venting (faster on cold rooms, slower on rooms that are too hot). Just takes patience.
  • pmchalepmchale Posts: 19Member
    And I checked the Pressuretrol settings, they are 0.5 and 1.5 psi. Should the diff setting be 1.0, instead of 1.5?
  • Gary SmithGary Smith Posts: 152Member
    not probably much impact, but yes, most recommend 1.0 for the differential. From what you have posted, the most impact will be from adding steam main vents at the ends of all the steam mains and then rebalancing the vents on the rads.
  • pmchalepmchale Posts: 19Member
    Gary - when you say "adding pipe lengths and EDR", do you mean increasing the diameter of some pipes? As you can sort of see from my schematic, most of the runs form a T off the feeders (from the mains) and feed a first floor and second floor combo of two radiators. After researching, I can clearly see that this is NOT the best piping setup. I sketched out what I thought might be a decent re-piping fix, which is essentially shown in the sketch I am attaching to this message. I would value your's and others' thoughts there.
  • Gary SmithGary Smith Posts: 152Member
    I'm sorry to have been unclear, I meant adding pipe lengths and radiator EDR to your schematic drawing, not adding actual physical pipe. That way some commenters here and perhaps you with help from the LAOSH book can see if some of the feed pipes from steam mains to radiators are too small or ok, most likely they will be ok or marginal and will work with good main vents and rebalancing the rad vents. I'm suggesting do the simple stuff first (main vents, rad vent rebalancing) before repiping. You might be surprised how forgiving an old steam system can be. One thing that steam systems are not forgiving about is poorly sloped or sagging piping where water can lay and steam can pick up and slam against the next bend. But, so far, you have not indicated that is the case with your system, so start with the simple stuff.
  • pmchalepmchale Posts: 19Member
    OK, Gary. I do indicate pipe lengths and diameters on the piping schematic. Lengths are noted next to pipes, such as "17ft" and diameters are noted in parentheses, such as "(2")". Where would you suggest main vents should be placed, as per my schematic? At the end mains, just in front of the Tees, that split into feeders going in opposite directions?
  • Gary SmithGary Smith Posts: 152Member
    Sorry I missed that. I would put main vents on the branches leading to:
    1. the foyer and 2nd floor bedroom
    2. the living room and 2nd floor bedroom
    3. dining room, 2nd floor bedroom and kitchen
    4. 1st floor bathroom (at lower right on your schematic) after the takeoff to the 2nd floor bathroom

    total of 4 main vents. I'd place them as close to the 90 deg bend as you can reasonably place them. Follow the general guidance in LAOSH (raise the vent a few inches at least above the main to minimize water or debris from getting to the vent).
  • Paul48Paul48 Posts: 4,492Member
    Can you do us a favor......use a different colored pen, and go over the parts of the pipe that are mains (horizontal pipe).
  • Paul48Paul48 Posts: 4,492Member
    Put a TRV on the living room and foyer radiators . If the dining room, second floor bedroom and kitchen over-heat, you might consider those, as well.
  • pmchalepmchale Posts: 19Member
    Updated photo attached. Orange pipes are all horizontal, sloping back towards the main or boiler. Nearly the entire piping system is horizontal in the basement, until vertical risers go up to the radiators. I obviously did not illustrate all the piping around the near boiler, such as the Hartford loop, etc.
    I labeled three "mains", but #3 is an add-on, I think, and basically just a branch. Again, I am no pro, so you may consider more pipes as mains, than I am. And thanks for bearing with me, for my lack of exact knowledge on all this, but I am learning.

    Sorry, what is "TRV"...some sort of vent, correct?
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