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Riser vents

LonnieLonnie Member Posts: 12
I have a 1 pipe steam system with f&t traps and main vents at the end of 3 loops. The system has a condensate pump. The system works ok. There is some trouble with getting heat to a couple of the radiators, and some water being spit out of a first floor radiator. I have several questions.
1) we had another radiator added to the end of the loop with the spitting radiator. It is closest to the trap and I believe the water is not being drained fast enough to prevent it being carried to the radiator air vent. What is the best way to solve this? Change the diameter of the return pipe?
2) main vents with f&t seem redundant. The f&t I would expect to do some venting. Would it be better to install riser vents just before the highest furthest radiator in that loop? Is there a valve that could be installed to replace the radiator shutoff valve that would accommodate a riser vent?
3) my boiler is an American boiler Vintage 1960. It seems to be working fine. Replace? I have no one close. Already looked on this website. I think I’m going to have to tackle it myself.


  • FredFred Member Posts: 8,418
    A 1 pipe steam system with f&t traps???? Some pictures would help us understand what you have.
  • LonnieLonnie Member Posts: 12
    I will post when I get home.
  • LonnieLonnie Member Posts: 12
  • LonnieLonnie Member Posts: 12
    First of four F&T traps. Just upstream is the main vent
  • LonnieLonnie Member Posts: 12
    Second F&T with the vent. Also, that leg is the one with the spitting radiator. Also the leg is very close to the waterline. Could be a dry return for part of it. It also connects to a common section that has another drain and F &T connected and that section definitely is dry for a portion of the return after the F&T.
  • LonnieLonnie Member Posts: 12
    Third F&T with a dry return for a portion.
  • LonnieLonnie Member Posts: 12
    Last F&T. Any help is much appreciated.
  • JUGHNEJUGHNE Member Posts: 6,793
    edited October 2019
    It looks like it was originally no F&T's and just a wet return with air vents on each main. Perhaps the wet returns became slow to return water and someone thought a pump would fix the problem.
    Is there any evidence of a wet return that was below the floor and was replaced with dry returns??
    Suddenly the pump was getting hit with steam and the solution was to add the F&T's. None look original to the system.
    Was the added rad the connection between the 2 unions?
    The riser pipe for that could be too small for 1 pipe steam.
  • FredFred Member Posts: 8,418
    I don't know where to start. Do you know when those f&t traps were added or what problem they were intended to solve? How many mains do you have? It looks like a parallel flow so the end of each main should drop below the boiler water line and no f&t traps or condensate pump needed.
    I see the gage glass for the boiler laying on top of the boiler. Is that a spare or do you not have a gage glass on the boiler anymore?
    What pressure is the boiler running at? Have you ever taken the Pressuretrol off and cleaned the pigtail (looped pipe) under it ? It is likely clogged and the boiler is probably running well above the 1 to 1.5PSI it should be set to run at.
    Where are you located? This system needs a pair of professional eyes, on site to determine how best to fix it, the right way.
  • Jamie HallJamie Hall Member Posts: 12,710
    Funny what evils occur when the boiler water line is lowered...

    You have work to do. The work can be done. But... any of the pipes to which you refer as partly or maybe dry or wet have to be set up so that they are either all dry or all wet (exception: the horizontal bit of return which is in the crawl space could be dry, with the water line about halfway more or less down the drop into the main basement). In some ways the simplest thing to do may be a false water line setup to restore the water line the system sees to where it should be.

    Then. Lose the F&Ts. You don't need them once you get the water line right. Put vents on the ends of all the mains. Lose the condensate pump.

    Run the system at no more than 1 psi; verify with a low pressure gauge.
    Br. Jamie, osb

    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.

    Hoffman Equipped System (all original except boiler), Weil-Mclain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
  • SeanBeansSeanBeans Member Posts: 482
  • LonnieLonnie Member Posts: 12
    edited October 2019
    @Jughne - The F&ts were replaced several years ago when I was here. I didn’t know better. But there were old ones here when I bought the place and were old. probably 20 yrs. I have no idea why they or the pump were installed.
    No evidence of any other returns. The new radiator is tapped in to the right of the unions in that picture.
  • LonnieLonnie Member Posts: 12
    edited October 2019
    @Fred -
    There are 3 steam headers with 4 drains. I was thinking I could just make the returns wet and remove the F&Ts and the pump but did not want to ruin a system that seems to be mostly working.
    The gauge glass is a spare.
    Pressure is set at 1psi. I never thought to clean the pigtail. I will do that right away.
    The closest knowledgeable person is 75 miles away.
  • LonnieLonnie Member Posts: 12
    edited October 2019
    @Jamie -
    I agree. A lot of work.
  • LonnieLonnie Member Posts: 12
    So a couple more questions.
    1) should I replace the boiler? Seems like I am on borrowed time. It is 50+ years old. If not, I will leave the system until it needs replacement, then correct it all together.
    2) I have a huge radiator on the first floor with a circumferential crack on the top of the first section. Anyone ever replace a section? Is it worth the work? I hear even if I can find a replacement section it will likely always leak around the pushnipple.
    3) I may be overly confident in my abilities, but I think I can complete this task myself. I have read a lot on this subject since I purchased this house and what I lack in experience I figure this forum can help. I just need to ensure I get the correct size boiler and have the right tools. Any advice on accomplishing either.
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