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low heat to 2nd floor ,2 pipe steam

hi,this is my first time posting a question so forgive me if i make any mistakes.

i have a customer who has a 2 pipe steam system that is having a problem. every radiator on the 2nd floor of their house will only heat about 1/2 way down. the 1st floor seems to be fine. they said problem only started when they installed new stat. i am not sure how this would cause problem. 2 other techs that have been here jumped the stat and ran system for over an hour and still get no heat upstairs.

the boiler was installed by my company about 3 years ago and has not had a problem since. the system has dunham 640 air seperator at the end of the return and 2 other main vents at the other end of the house.

i have not been to the house yet but i will be going this week and any feedback would be great.


  • nicholas bonham-carter
    Dunham air eliminator

    Check all the valves, and traps (radiator, and crossover), and the pressure. Those old Dunham traps may have problems opening at excessive pressure.

    Is any air coming out of the air eliminator?

    Is there just one return line or several?

    In mildly cold weather, the rads may not get hot all the way across, but should all get equally hot-- NBC
  • steve11
    steve11 Member Posts: 2
    air eliminator

    thanks for your quick reply.

    from what i was told there was no air coming out of the top of the eliminator.

    they also said that the eliminator was cold the entire time.

    from the pictures i have looked at there looks to be several returns that lead back to the air eliminator.

    the temps here in upstate N.Y were in the low teens last week