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Radiator only partially heating up, is it a supply issue or is radiator blocked inside?

rhodebump Member Posts: 152
This is a Two-pipe system. I have two identical radiators. One radiator is fed at the beginning of the main. This rad is fine.
The 2nd rad is fed from the end of the main line. It's only partially heating up. I see the steam is getting to it (see pic). I have a hole for a vent (that I removed) and a steam trap (that I removed for testing). No steam is coming out of the vent hole or the steam trap. Steam trap does release water. I hear slight gurgling from the air vent.
I put a good pitch on the 2nd radiator so the condensate end is a couple inches lower than the steam intake.

I am trying to decide if this is a problem with not enough steam supply or if the radiator has an internal blockage of some kind. Rads are 81" long, 21" tall, 5" wide.

Here is a picture of the bad rad

Here is a picture of the good rad

My thought is that if hot steam is getting to the rad, does that indicate that the problem is with the rad?

Thank you. I already busted out the pipe threaders/etc to run another line and questioning doing that work.


  • SteamingatMohawk
    SteamingatMohawk Member Posts: 1,005
    What happens if you temporarily shut the valve to the non-problem radiator?

    Post a picture .

    Don't run the system with the radiator off line for a long time, just long enough to determine the temperature profile of the "non-working" one.
    EBEBRATT-Ed Member Posts: 15,524

    Just a possibility is the supply valve to that radiator the disk or some internal part fell off and is blocking the pipe
  • rhodebump
    rhodebump Member Posts: 152
    Thank you for responding. Unfortunately, there is no radiator valve on the good radiator.

    The problem radiator has never functioned before, the supply pipes were rusted out/disconnected. I just connected re-connected it to a new location, installing a new radiator valve.

  • dopey27177
    dopey27177 Member Posts: 887
    If there is a steam trap on the end of the radiator the element may be collapsed and shut. or if the element is in the open position steam may be comming up the return and stopping the steam flow thru the radiator.