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Steam Baseboard spitting water

mmc239 Member Posts: 81
My living room has steam baseboard which seems to have alot of air in it. Is there a way to bleed air from steam baseboard? When I turn heat on, while it’s heating up it bangs and spits water out of air vent which I just replaced and is brand new. Once the baseboard is heated up it’s fine. 


  • Snowmelt
    Snowmelt Member Posts: 1,418
    That can on the end is supposed to let air out,I don’t think it’s working
  • Jamie Hall
    Jamie Hall Member Posts: 23,536
    Probably does have a lot of air in it. That's the nature of steam heat -- it will refill with air every time the boiler shuts off.

    Now. What vent did you install? Baseboards are very tricky on steam, and you need the best vent you can buy -- and a relatively slow one.

    Second, if it's banging and spitting water, how is the baseboard pitched? A baseboard on single pipe steam can be made to work, if it's not too long and if it's pitched aggressively back down towards the inlet. Half an inch per foot of length is not going to be too much.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • neilc
    neilc Member Posts: 2,711
    can we see how the other end is piped?
    that may affect answers here also,
    known to beat dead horses
  • pedmec
    pedmec Member Posts: 994
    That's a lot of baseboard for counterflow. You need to reduce how fast the air is leaving, not increase it. By reducing the the air leaving you are reducing the steam entering. this will reduce the velocity of steam entering and the amount of condensate being produced. This combination will allow the condensate to slip past the incoming steam. Considering that it works when heated then i think this should help you. But i am surprised it gets quiet at all with this amount of baseboard. Also make sure that the radiator valve is completely open.

    If you do this you do have one caveat. Making sure you get enough heat. I don't think its going to be noticable but he might be trial and error.

  • JohnNY
    JohnNY Member Posts: 3,244
    Steam baseboard is an oxymoron.
    Contact John "JohnNY" Cataneo, NYC Master Plumber, Lic 1784
    Consulting & Troubleshooting
    Heating in NYC or NJ.
  • mattmia2
    mattmia2 Member Posts: 9,838
    JohnNY said:

    Steam baseboard is an oxymoron.

    Especially when it is fin tube.
  • mattmia2
    mattmia2 Member Posts: 9,838
    Do you have access underneath? You could pitch it to the vent end and add a drip that connects to a return below the water line at the vent end.

    You could also add piping below the water line at the boiler and a circulator and run it as hot water.

    Your best bet would be to find a standing or wall hung cast iron radiator you can replace it with.

    Is this the only baseboard on this system?
  • Gsmith
    Gsmith Member Posts: 433
    Replace that Varivent with a traditional slow radiator vent like a Ventrite #1 set at low setting. That varivent is too fast for the baseboard and even at the slowest setting will cause spitting.
  • mattmia2
    mattmia2 Member Posts: 9,838
    Now that i think it through that section of fin tube has like 1/20th the volume of a ci radiator so very slow venting is what would at least somewhat balance it with the rest of the system.