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BSPT X NPT Adapter:

icesailor Member Posts: 7,265
I just installed a Veissmann Vitodens 100 boiler. I used the Veissmann Low Loss Header. It comes with all the fittings to do it. The header comes with a plug in the bottom which comes installed. They give you an adapter to connect into the port where this plug is. The plug seems to be 1/2" but it has an O-ring to seal it.  The adapter is described as a "BSPT X NPT adapter". There is no shoulder for the O-ring. I put 5 wraps of Teflon tape and used Rectorseal #100 Teflon tape on the threads. It leaks even though I cranked on it.

What's the story on "BSPT" threads?


  • Gordy
    Gordy Member Posts: 9,537
    edited March 2011
    British Standard Pipe Thread

    STEVE PAUL_3 Member Posts: 126
    BSPT fittings

    The BSPT designation stands for "British Standard Pipe Thread", and is also referred to as "British Standard Pipe Taper". Both are commonly used. This thread because of it's taper, is similar to the American NSPT pipe thread. Both become pressure tight upon proper torque and thread makeup. A sealing gasket or "O" Ring is not required.
  • CMadatMe
    CMadatMe Member Posts: 3,086
    edited March 2011


    Use Loctite or get out some wicking...By the way try Taco's LLH. Makes for an easier install and has better air removal. Also already mounted on strut. Cost is right there with the Viessmann...

    "The bitter taste of a poor installation remains much longer than the sweet taste of the lowest price."
  • EricAune
    EricAune Member Posts: 432
    I 2nd Chris's remedy

    Loctite for these threads seems to be the ticket.  I have had similar problems with panel radiators and Loctite (teflon type) has rid all leaks from the start.
    "If you don't like change, your going to like irrelevance even less"
  • icesailor
    icesailor Member Posts: 7,265
    edited March 2011
    BSPT X NPT Adapter:

    Thanks all. I'll just crank it some more. I have plenty of Teflon Tape on it and it shouldn't have leaked. I'm not one to over tighten things. When I took off the factory plug, it had an O-Ring on it. It didn't come out easily. It took a socket to do it.

    The Veissmann LLH is nice because they offer the insulation kit for it. Which I used.

    I knew that BSPT stood for something stupid. Stupid me for not figuring it out. Old age setting in.
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