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Steam radiator supply valve leaking. Replace?

Have a one-pipe steam radiator. The supply valve is leaking water from the bottom of the big nut.

Leak rate is 1-3 drops per second. The valve is in otherwise good condition. Prior to this the radiator and supply line were making loud banging noises. Maybe it somehow got unseated or bent.

So my question is...does the valve need to be replaced? Was hoping it just needed to be reseated at the nut.


  • Reseat the union faces by loosening the nut, cleaning the mating surfaces, lubing with a bit of dishwashing liquid, and retightening the nut. Rocking the radiator while tightening can help with the proper alignment.—NBC
  • Tast43
    Tast43 Member Posts: 2
    Thanks! Turns out one of the threads was damaged (cross-threading by previous installer). Ended up replacing the whole valve and union nut. No more leaks.