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Flooded radiators

mfritzg
mfritzg Member Posts: 4
Struggling to find a solution, single level county building built in the 60's, steam boiler replaced in the last five years, radiator only heating, thermostatic valves and floats replaced on all of the radiators with in the last five years. On very cold days, when the entire building is calling for heat all appears to be working correctly, Once some of the areas satisfy and the overall load drops, the remaining radiators that are still calling for heat flood with condensate. Thank you in advance.

Comments

  • BobC
    BobC Member Posts: 5,401
    Several things to check-
    Near boiler piping
    Slope of mains and radiator piping
    Possible failed traps

    Does the water level in the sight glass bounce around a lot when making steam? Post pictures of the boiler and the [piping around it.

    Bob
    Smith G8-3 with EZ Gas @ 90,000 BTU, Single pipe steam
    Vaporstat with a 12oz cut-out and 4oz cut-in
    3PSI gauge
  • Jamie Hall
    Jamie Hall Member Posts: 21,106
    Is this one pipe or two pipe steam? Could make a big difference in where to look and what to look for.

    What pressure does the boiler run at?
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • mfritzg
    mfritzg Member Posts: 4
    Thanks Bob, all piping appears to slope correctly, traps have been checked, I have not noticed the sight glass bouncing, I will verify and also post pic's tomorrow.
    Thanks Jamie, it is a two pipe system and 5# pressure.
  • BobC
    BobC Member Posts: 5,401
    Why 5#? That seems awfully high, do you know if there is a specific reason?

    Bob
    Smith G8-3 with EZ Gas @ 90,000 BTU, Single pipe steam
    Vaporstat with a 12oz cut-out and 4oz cut-in
    3PSI gauge
    KC_JonesJUGHNE
  • mfritzg
    mfritzg Member Posts: 4
    Unknown, the facility engineer indicated it has always been operating around 5#. Too high possible?
  • Jamie Hall
    Jamie Hall Member Posts: 21,106
    The reason I asked is that you may be backing water out of the boiler into those radiators when the pressure rises. In fact, 5 pounds will raise water about 16 feet. You say that this is a one story building. Even if the boiler is in the basement, that's enough to flood all the pipes in the ground floor very happily, never mind their returns -- unless there is a really truly bullet proof way to keep that from happening (and note that check valves absolutely won't do it).

    A scenario which I can envision is that the boiler runs very sweetly at a half a pound or less, and gets much of the radiation filled. Condensation slows, pressure rises, water backs out, radiators flood and there you are...
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • Jamie Hall
    Jamie Hall Member Posts: 21,106
    11.5 feet. Not 16 feet. I can't add...

    But it's still enough to possibly cause a problem.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • mfritzg
    mfritzg Member Posts: 4
    Gentlemen, thank you, we will drop the pressure down and monitor the performance, I will send pic's of the system tomorrow and let you know how it performs with lower pressure.
  • JUGHNE
    JUGHNE Member Posts: 10,568
    From my limited experience, what I've seen is that lower is almost always better, as long as it heats the building....one exception being if the steam pressure is required to lift the condensate coming from an F&T trap, then some lbs are required. FWIW
  • nicholas bonham-carter
    nicholas bonham-carter Member Posts: 8,573
    Jaimie, I think you hit the nail on the head! Oh the evils of over-pressure. That 11 feet of rise would certainly block the the dry returns, and flood the radiators..--NBC