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Clearing Obstruction?

Hello all,



I have been sort of thrust into a property management position recently and I am dealing with a problem with the heating on a 3 family house.



It is a gas fed, single pipe steam system with one gigantic, older-than-dirt boiler supplying all three apartments. I do not know its history before I came into the picture and I highly doubt it has had any annual service in some time.



The people on the third floor are constantly complaining about radiators not working so I have replaced the steam valves, checked for proper slope and checked the gate valves. Eventually we figured out that the pipe running to two of the radiators (is that normal - two radiators on one pipe?) was not warm when others were. We traced the cold pipe to a very specific point. Below that point the pipe was warm. That seems to indicate some kind of blockage.



I have found references here to clearing such obstructions with a garden hose, and I think I get the gist of it, but anyone willing to walk me through it?



I guess my biggest question is where do I let the water out? From the flush valve off the boiler? Can I damage something in the boiler by doing this?



Thank you

Comments

  • Steamhead
    Steamhead Member Posts: 14,324
    First check

    the pitch of that pipe and any other horizontal pipes coming after that point. A water pocket in an off-pitch pipe can cause this problem, and it doesn't necessarily have to be where the pipe turns cold.
    All Steamed Up, Inc.
    "Reducing our country's energy consumption, one system at a time"
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
    Baltimore, MD (USA) and consulting anywhere.
    https://heatinghelp.com/find-a-contractor/detail/all-steamed-up-inc
  • Jim_L2009
    Jim_L2009 Member Posts: 4
    Level

    The horizontal pipe in question is level. Should it be sloped downward towards the boiler?



    This pipe does not run directly into the boiler. It is slightly above and perpendicular to a larger pipe that runs into the boiler. It is connected with a 45.



    I do know that the third floor apartment was converted from a former attic, so I am guessing the heating system was added on after the original set up.





    Thank you
  • Jamie Hall
    Jamie Hall Member Posts: 15,340
    not level!

    One pipe steam particularly -- "horizontal" pipes are never level -- they always have to pitch back to the steam main, and the steam main has to pitch either to the boiler or to a drip at the far end to a return.



    In the case of a runout, which is what you are describing, the pitch should be 1/2" per foot.  However... you also need to be sure the pipe is big enough.  You note that this pipe goes to two radiators (which is fine, by the way, so long as it isn't first to one, and then to the other, but actually branches and goes to two... if you follow me).  You need to estimate the square feet of radiation connected to this pipe to determine if it's big enough.  If you have a copy of The Lost Art, the chart is on page 89.  If not, figure the square feet of radiation and post it back and we can give you the proper pipe size.



    Flat out obstructions in a steam pipe are pretty rare -- after all, what's to get in there?
    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
  • Jim_L2009
    Jim_L2009 Member Posts: 4
    Square Footage

    The pipe is 1.5".



    The rooms are small and they have slant in ceilings in significant portions of them. I have asked the tenants to get me the exact square footage, but I haven't heard back yet.



    In the meantime, the rooms in the unit underneath (which have the same layout) are about 300 square feet put together.





    Thank you
  • Jamie Hall
    Jamie Hall Member Posts: 15,340
    Not

    the square footage of the rooms -- the EDR of the radiators connected to the pipe.  Inch and a half will take 81 square feet, max.
    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
  • Jim_L2009
    Jim_L2009 Member Posts: 4
    EDR

    According to my measurements and the chart at:



    http://www.colonialsupply.com/resources/radiator3.htm



    The EDR for one radiator is 25 and 20 for the other. 45 total. Well below the 81 cited above.



    Thank you
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