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Steam convector not getting hot

Hello guys,

I'm having a problem with a wall convector on a steam system not getting hot. I'll post a picture of the unit but there isn't any obvious valves or steam traps that I can see and from what I've been reading that is usually what causes these to not work well. The unit is on the second floor of the house and is probably the furthest from the boiler. The house has a combination of radiators and wall convectors and it seems like the radiators get very hot and the wall convectors are so so. I have an IR thermometer / temp gun so I can see the incoming pipe is 190 degrees and the outgoing pipe is 65, so it sounds to me like the unit is "air bound" but I don't really know how to tackle that problem. I've replaced all the vents I found in the basement with Gordon #2's but it hasn't helped any.

Thanks in advance for any advice.



  • Jamie Hall
    Jamie Hall Member Posts: 22,908
    If the air can't get out

    the steam can't get in.  And it is quite obvious that the steam isn't getting in.  In fact, if your IR thermometer is correct, it probably isn't even getting to the inlet side, never mind in.

    First question: this looks like a two pipe system.  Are all the convectors -- which you say are so so at best -- on the same main in the basement?  Does that main get steam?  Do the risers to the convectors get steam hot?

    Second question: if there are no traps on the outlets, or funny bits of hardware, where do the outlets go?  If there are no traps, there must be a way to keep any steam or air in them from getting elsewhere in the system, and thus it would seem they might go to a wet return.  In which case, how does the air get out of them?  Are there any vents on the outlet side?  And do they work, if they are there?

    Then while you are chasing pipes around to see where they go, check with a level and make sure that everything is pitched properly.  A low spot in either the steam runout, or in a return, can do this -- although usually you would hear a water hammer from that.  But not always...
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • Noel
    Noel Member Posts: 177
    Are the steam pipes insulated?

    They need to be, in most cases, to get the steam to the end of the run on a line that is just big enough to feed the radiators on it.

    Many times, the pipe has extra capacity, and will work with the insulation removed, but not always...
  • Joe_152
    Joe_152 Member Posts: 2
    I think

    That the convectors are all on the same main in the basement and I believe the steam is getting up the risers since the radiators get very hot. None of the units have individual vents on them, there are only vents in the basement piping. I've found 4 Gordon #2s that I believe are working since I can hear them hiss for a while then stop. I also found a Hoffman #74 that I replaced with a Gordon #2 after I read somewhere that the 74 was only for small individual units. And the last one I found was an old Trane vent that didn't have a model number on it and looked ancient so I replaced it with a #2 as well.

    I figured at best I had to be increasing the amount of air that can get out of the piping. I'll have to head down there and check the pitch of the pipes.
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