Welcome! Here are the website rules, as well as some tips for using this forum.
Need to contact us? Visit https://heatinghelp.com/contact-us/.
Click here to Find a Contractor in your area.

Replacing convector help

bdwild Member Posts: 25
Hi All,
Geez I'm addicted to this site! More to come improving my system but for now I'm fixing some leaks. First up is replacing a leaking convector. The unit should be here tomorrow, and here's a photo of the replacement valve. I'm good on the threaded parts but
My question: Do I need to seal the mating faces of A and B with anything, or just tightening seals the deal?


  • Jamie Hall
    Jamie Hall Member Posts: 23,652
    That's a union. The seal is between the very smooth left hand ring of part A and a corresponding female ring inside the valve itself. The big nut -- part B -- serves to hold the whole thing together. Don't forget to put part B on the nipple into the radiator before you thread part A onto the nipple!

    The threads from part A onto the nipple should have sealant, like any other threaded plumbing joint. Use your favourite. I'd probably use Blue Monster, but that's me. The mating surfaces of the union -- part A into the valve -- do not need any sealant, and shouldn't have any. However, you may find that to get it to take up snug it helps to rock the radiator slightly back and forth.

    The assembly will not compensate for misalignment -- get things straight before you begin.

    The final assembly shouldn't leak (of course) but you needn't be a gorilla on part B -- good and snug, yes, but don't overdo it.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 8,167
    @Jamie Hall Nailed It!

    Here is a picture. The inside here means pipe dope on the outside of the pipe nipple as JH indicated

    Edward Young Retired

    After you make that expensive repair and you still have the same problem, What will you check next?

  • bdwild
    bdwild Member Posts: 25
    Thanks much @Jamie Hall and @EdTheHeaterMan, for all the important tips! Yes, got some Blue Monster and yeah, I've gone over that "dont be leaving the part B aside" about 10 times now, LOL!
    Do you guys teflon tape and dope, or just dope?
    Appreciate your help!
  • nicholas bonham-carter
    Don't forget a little dish-washing liquid will help to mate the union surfaces, as you are rocking them back and forth, while tightening the union nut.
    This is not for sealing Per Se, but for enabling the union faces to slide properly together, as they are tightened, and rocked.--NBC
  • bdwild
    bdwild Member Posts: 25
    Thanks NBC - will do!
  • bdwild
    bdwild Member Posts: 25
    Another question on these valves if you would... I plan to replace three that are leaking - two are 1" and one is 1 1/4". As I hope you can see in the photos (all handles are turned to full open), the two 1" valves open all the way to where the inner plate seats at top of bonnet.
    The 1 1/4 does not. It's at least a 1/4" if not 3/8 away from seating.
    Is this "fully open"? Did I get a faulty valve?