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Cast-Iron Radiators

Jim Bennett
Jim Bennett Member Posts: 607
I have only done this one time so far, removing a flawed section of a steam radiator. I used RectorSeal 5 on the push nipples and it has worked fine for about the last five years!

Hope this helps,


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  • Tom_57
    Tom_57 Member Posts: 2
    Reassembling a hot-water cast-iron Radiator - Is sealant needed?

    I have hot water radiator that I shortened from 13 sections down to 7 sections. The sections are connected by two tapered cylinders about 2" in diameter at the top and bottom of each section. I read the very helpful article on this site regarding this topic. However, my radiator seems to differ a little from the push pins mentioned. Primarily, I am concerned about getting a leak tight seal when I press the sections together. Is there a certain type of sealant I should use, like pipe dope? or is the pressure from forcing the tapered cylinder into the female end adequate to make a water tight seal? Thank you, I appreciate any help.
  • J.C.A._3
    J.C.A._3 Member Posts: 2,981

    I had a couple of "mistakes" this fall while replacing 12 radiators in a place that froze. A couple of the end sections were fractured while configuring the radiators for a hot water install.

    These were all brand new Burnham units and for every repair, we got new tapered bushings for connecting the sections. If you are trying to use the old ones, DON'T. Find new ones and make sure you draw them in as evenly as possible. For a lubricant/sealant(?), I also use only Rectorseal #5. Best of luck. Chris
  • Tom_57
    Tom_57 Member Posts: 2
    Cast Iron

    Just an update on Jim and Chris's advice. I used RectorSeal 5 to seal two sections of my cast iron radiator after shortening the radiator. In the end it was a success. I did encounter a little leaking because I think failed to use enough. After disassembling again and putting on a generous amount of sealant, she is is not leaking. Thanks guys.
  • Gounthar Frankfurt

    In France, the plumbers use paper seals (yes, paper!) when changing elements in hot water cast iron radiators...
  • Mike T., Swampeast MO
    Mike T., Swampeast MO Member Posts: 6,928

    I run a small bead of pure silicon around the nipple. Never had a leak.
  • bschaller
    bschaller Member Posts: 2
    edited October 2013
    Broke off bushing, cast iron radiator...what next?

    Posted in the wrong place.
  • nicholas bonham-carter
    nicholas bonham-carter Member Posts: 8,578
    Methode Francais

    In France the toilet paper has such special qualities, like wax paper, that I am sure it could seal anything, even though not so good for it's intended purpose!--NBC
This discussion has been closed.