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Suspect Clogged branch from steam main

lgag
lgag Member Posts: 4
Two floor bldg.One pipe steam heat.The furthest radiator from the boiler on the first floor never heats up.(sometimes the first section or two only).Radiators whose takeoffs from header are downstream get hot.Replaced radiator vent,added main vent to inlet of radiator valve.Also installed added venting capacity on main (Gorton #2 and #1).This radiator has had this problem for a very long time( i would say about 35 yrs that im aware of) I have decided to try and finally fix it.Same room on second floor got much better results when i added gorton #2 to inlet of valve also.Pressuretrol is set to cut in at 0.75 psi and cutout at 2.2 psi (used pump and calibrated gauge to configure.I am pretty sure this branch to this radiator has been clogged for a very long time.I was told to try backflushing the pipe from radiator back to header with a hose.Water flows back into header and wet return (not completely plugged).It is 1 1/4" pipe,approx 20 ft run with 2 ninety's and 4 45's.How can i determine where in the run the clog is located?Remove insulation and listen for boiling water thats blocked?Cut pipe and inspect with camera? I


s there a chemical that might work?
Thank you for any help you might provide.

Comments

  • Long Beach Ed
    Long Beach Ed Member Posts: 1,202
    edited December 2022
    Steam pipe clogged? I doubt it.

    You ran water through it. Can't trust yer own lyin' eyes?

    Check your pitch of everything. If clogged with anything. it's water. But it's not. Check your valve. You have a balance problem. Get some 1/8" pipe plugs and start plugging up other radiator vents. I'll bet that guy will heat.

    If you have wide open vents all over the place, the radiator with the most pressure loss in its runout just isn't seeing any steam. Once the others begin condensing, they are drawing steam away from this last radiator.

    Cut down on the venting elsewhere.
    BobC
  • bburd
    bburd Member Posts: 912
    If venting is adequate, this problem is usually caused by a low spot in a pipe that collects water, which will condense much of the steam before it can reach the radiator. As noted above, check pipe pitch.

    Bburd
    Long Beach Ed
  • neilc
    neilc Member Posts: 2,702
    does the added valve main vent get hot?
    try removing it and run the boiler,
    does it vent?
    do you hear a panting or gurgling from the open vent hole?
    known to beat dead horses
  • lgag
    lgag Member Posts: 4
    The added main vent does not get hot. Steam is not reaching it. The pipe going upstairs that is right next to it is and that is taken off just downstream on header. I have removed the vent off the radiator,no panting or gurgling. Radiators downstream on main work ok. The building has just 7 radiators,they get hot. The pitch looks pretty good. If I remove the insulation will I be able to listen and find spot that water is accumulating?
    Thank you 
  • Long Beach Ed
    Long Beach Ed Member Posts: 1,202
    Go to Home Depot and rent a drain snake for $30. Snake the steam runout. When that does nothing, consider doing what I suggested.
  • neilc
    neilc Member Posts: 2,702
    lgag said:

    I have removed the vent off the radiator, no panting or gurgling. Radiators downstream on main work ok.

    ok, but, what about the vent before the valve and rad?
    just trying to eliminate the valve, and rad,

    is that insulation snug to its piping? or is there wiggle room?
    you can kinda eyeball the insulation, against the ceiling,
    but to be sure you would want to strip insulation,
    see if the main hole gurgles before looking too hard, those twin lines in the basement don't vary much from each other from what I can see,
    that run along the wood, may be a bit long, between hangers, (maybe a sag?)

    someone else mentioned plugging or slowing other vents to just to see if more steam can get directed to this dead line,
    known to beat dead horses
  • Jamie Hall
    Jamie Hall Member Posts: 23,273
    "Looks prtty good" just won't do, unless your eyes are a lot better than mine. Get out a level and actually measure the pipe. The whole length of it.

    Not to say that you may not have a stoppage, but it will be mechanical -- and the first place I would look is the valve to the radiator. Any possibility that the valve itself has come apart and the closure is just sitting there blocking the steam?
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    Long Beach Ed
  • lgag
    lgag Member Posts: 4
    "Looks prtty good" just won't do, unless your eyes are a lot better than mine. Get out a level and actually measure the pipe. The whole length of it. Not to say that you may not have a stoppage, but it will be mechanical -- and the first place I would look is the valve to the radiator. Any possibility that the valve itself has come apart and the closure is just sitting there blocking the steam?

  • lgag
    lgag Member Posts: 4
    I will double check again and also check the venting at the other radiators. Thank you for your help and suggestions 
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 15,512
    @ 20' run with 2 90s and 4 45s is a long run and a lot of air to vent. I would take your riser vent off and install a valve in its place temporally. Run the boiler and turn the pressure control up temporally and see if you get steam. If the water runs back when you flushed it, you should get steam unless the pipe has a low spot
  • Big Ed_4
    Big Ed_4 Member Posts: 2,780
    I seen a offset from a riser to the radiator plug up . It was hard as a rock.
    I have enough experience to know , that I dont know it all