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baseboard radiator heat adjustment

Hi, newbie boiler owner. I have a 1950s house with a relatively modern boiler, but some older (possibly original) baseboard radiator units in the house. Some rooms are too cold or too hot, so I'm trying to figure out how to adjust heat output on the baseboard radiator itself.

Most radiators have something that looks like this:

Others have these:

Do I simply twist these in one direction or the other to lower/raise heat output? If so, are twist directions to raise/lower heat pretty universal? E.g., will twisting clockwise typically raise heat output or lower?



    JUGHNE Member Posts: 11,055
    The top picture is of manual air bleeder vent. You need a square key. You open to let air out and close when water shows up. There can be no air in the system for it to work correctly.

    Can you clean the fittings up on the bottom picture and take a better picture?
    Brush and vacuum. Back up a little to get it all in focus.

    Do all the heaters look the same, pictures of them also, back up to take them.
  • mattmia2
    mattmia2 Member Posts: 9,622
    Some pictures of the baseboard radiation, both the element and cover would help too. Typically you adjust the damper to change the heat output but i'm not sure yo have that type of baseboard. Get that whole shaft to the top end too on the second picture.
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 7,817
    edited February 2021
    It is difficult to determine what type of heat emitters you have from those close up pictures of the items you posted.

    There are two baseboard heaters that were popular in the 1950s
    Cast iron looks like these

    And the lower price aluminum fin element on copper (and sometimes steel) pipe.

    They both provide about the same output BTU per linear foot, at a slightly different piping configuration below the floor. Your piping design connection below the floor will make a difference in how to control the heat output. It is safe to say that covering the radiator with something will reduce the convection air currents over the heating element and reduce the heat output. there may be easier ways already designed into the heating element design.

    Better pictures will help us guide you.

    Yours Truly,
    Edward F Young. Retired HVAC ContractorSpecialized in Residential Oil Burner and Hydronics
  • Is your system steam or hot water?--NBC
  • Hap_Hazzard
    Hap_Hazzard Member Posts: 2,846
    If you have a steam system, the best way to adjust the heat output of a baseboard is to adjust the airflow through it.
    Just another DIYer | King of Prussia, PA
    1983(?) Peerless G-561-W-S | 3" drop header, CG400-1090, VXT-24