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Main Vent for steam boiler

Pegret Member Posts: 37
edited January 2019 in Strictly Steam
Could location of the main vent effect one of the radiators not coming on except when therm temp is turned up by 3 or more degrees? Rad doesn't work when trying to manitain same temp throught the day, only when it's turned up by 3 or more degrees.
The main vent it located very close to the boilder. Can another main vent be installed closer to this rad to help get heat to it?


  • JohnNY
    JohnNY Member Posts: 3,226
    See my comment in your other thread on this topic. But yes is the answer to your question.
    Contact John "JohnNY" Cataneo, NYC Master Plumber, Lic 1784
    Consulting & Troubleshooting
    Heating in NYC or NJ.
  • nicholas bonham-carter
    nicholas bonham-carter Member Posts: 8,576
    If this is a parallel flow system, then the main vents, which will be at the end of the dry return are close to the boiler, but still correctly placed.
    Are all of the other radiators getting steam at the same time, except for the problem one?
    Is your backpressure of venting less than 2 ounces?—NBC
  • Pegret
    Pegret Member Posts: 37
    NBC - I'll have to ask the plumber your question as I don't understand the lingo. Thank you
  • Pegret
    Pegret Member Posts: 37
    All other radiators get staem at same time- this one only works when temp is increase by 3 or more degrees at thermostat. Does not work when maintinaing same temp.
  • Fred
    Fred Member Posts: 8,542
    edited January 2019
    It likely doesn't get heat unless the thermostat is turned up by 3 degrees because, with that turn up, the boiler runs long enough to push all the air out of the mains so that steam gets to that radiator. What size main vents do you have on that main/return? It may be too small or it could be failed closed. What size vent do you have on that radiator? Is there any banging anywhere on the main, after the last hot radiator or on the radiator pipe that runs to that radiator? If so, there may be a dip in the pipe or it has lost its pitch and is holding water, causing the steam to collapse before it gets to that radiator. Does the radiator, itself have some pitch so that water can drain out of it?
    These are the things that are suspect.
  • Pegret
    Pegret Member Posts: 37
    thanks for all ideas and questions. I'll run these by my plumber and hope this can finally be resolved!