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Gurgling / water build up/ spitting air valve

I'm coming up on my third winter in my 2 story house which has a 1 pipe system. Through the last two heating seasons there have been a host of issues which i've dealt with mostly by covering my hears or putting rags under spitting air valves.....This year i set out to try to have a great running system.

After a lot of internet research and reading i spent all of today replacing the main air vent (i installed a gordon no 1), adding a "master vent" also a gordon no 1, and balancing the air vents by changing the sizes of the inserts. The "master vent" i installed on the steam inlet pipe before the farthest radiator on the second floor. The idea here was to vent the main and the riser quickly. This radiator in past years had I hard time getting hot and always had water in it.

So after spending the day making these mods, I fired up the system. No banging like years past, yes! I ran around the whole house checking the rate at which the radiators were heating, very evenly, yes! After 5 mins or so, all but two of the radiators had heated evenly throughout. The last two on the 2nd floor (one has the master vent) only heated 50% through and water started building up in the radiator and spitting out the air vent. NO!! Failure.....

I dont know what else to do. Same two radiators same problems. I have a no 6 and C size vents on these two rads. 6 on the rad with the master and C on the other.

Should I go bigger to Ds on each or smaller to 5s on each. I just have this feeling like its something other than the vent sizes. What I dont understand is how this water builds up in the riser. These rads also "breath" they push air out and pull air in.


  • JStar
    JStar Member Posts: 2,752

    Have you checked the riser size against the connected radiator load? You may be venting TOO fast. Frustrating, right? Venting too fast could lead to excess condensation building up too quickly.
  • Rich_L
    Rich_L Member Posts: 81

    Are your radiators and piping in question "sloped" toward the steam line? They need to be to properly drain against the entering steam. 
  • kcopp
    kcopp Member Posts: 4,432
    you said you....

    did some modifications? Other than changing vents did you do anything else? Did you move any piping.... spitting vents generally means wet steam... either dirty/ oily water or poor near boiler piping....
  • crash2009
    crash2009 Member Posts: 1,484
    Sounds like

     you have the venting to the last rads straightened out.  Two questions come to my mind.  How well are these 2 problem rads drained and insulated?  Are the sizes of everything between the main and the radiators correct?

    see pages 85 to 91 in the Lost Art Of Steam Heating

    Also are you sure the radiator valves are completely open. 
  • gerry gill
    gerry gill Member Posts: 3,078
    Could also be

    The boiler is to big for the load which would cause critical velocity to be achieved in the runouts. If achieved, the water won't flow back against the flow of steam. Boiler firing rate as compared to load and pipe size, would need to be figured out to answer that.

    Could also be to much pressure build up. Is the pigtail clean? Is the pressure control working? Are the pipes insulated well?
    Serving Cleveland's eastern suburbs from Cleveland Heights down to Cuyahoga Falls.

  • vincer652
    vincer652 Member Posts: 3
    round two

    This morning I changed the orifice inserts to number 4s on the two problem rads and ran a heating cycle. Unlike yesterday, the rads did not gurgle or spit and they heated up 8 of the 10 fins, better than yesterdays run where they only went up to 5 of 10. I feel like this is not going to give me the heat output i will need this winter season as things get colder. The riser size is 1 1/2" up to the two. I am running the boiler (187000 btu) at just under 1 psi.

    All my homes rads are sloped toward the inlet valves, i flushed the hartford loop and the boiler yesterday i few times.

    When i ran the heating cycle this morning, I checked the water level in the boiler at the sight glass and noticed it moved up and down a bit.

    The only two things I have left on my to-do list is insulate the mains and boiler piping and I was thinking of lowering the water level a bit. Beyond that I dont know what else to do to get the two problem rads to heat through out and hopefully not gurgle or spit.

    Someone mentioned cleaning the pigtail...I guess I will try that too. The adventure continues....
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