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Buderus Logalux LT DHW output nipple thread type

timo888timo888 Posts: 137Member
We had a Buderus oil furnace and Buderus Logalux LT hot water tank installed by the oil company about four years ago. Just noticed lots of green, reddish-brown, and white sediment caked around the DHW steel supply nipple (AB in the attached brochure) where a brass Tee fitting connects to it--possibly galvanic corrosion or mineral deposits from a leak that resolved itself. I want to remove the brass fitting from the steel nipple and put a dielectric union there. The Logalux LT product brochure identifies the steel DHW supply nipple thread as 1" but doesn't indicate NPT or BSP. It's probably NPT but since some Buderus threads are BSP I'd like to be certain. Help/info appreciated.


  • faneuilmikefaneuilmike Posts: 6Member
    output nipple

    I have the same situation on my ST tank. I have no apparent leak. I cannot answer your question but i will be changing the male adapter shortly when I change the anode and clean the tank.
  • timo888timo888 Posts: 137Member

    Buderus tells me that the steel nipple is 1" NPT.
  • EddieGEddieG Posts: 150Member

    It is 1"NPT. Usually were that tee you speak about connects to the tank, they have a plastic insert. I believe that is why they do not require a dielectric union. The tee is shipped with the tank by Buderus. I think you just have a leak and it is not related to the metals. Not saying that the dielectric union will hurt anything. 
  • timo888timo888 Posts: 137Member
    plastic sheathing?

    Eddie, not sure what you mean by 'plastic insert'. Is this a plastic sheathing around the steel nipple? I really can't see anything because of all the multi-colored crud. Looks like there's some sort of foam collar.
  • EddieGEddieG Posts: 150Member

    When you get the tank new, you can see a plastic piece that goes through the female connection and surrounds the top of the fitting. It looks similar to a dip tube you would see on an electric water heater cold connection. I am assuming that Buderus uses that piece of plastic to separate the metals. Based on them shipping the brass tee and showing it directly installed on the IDWH. Not sure, but I think so. I have had that same issue you are describing on a job. We know use a Smart Thread Sealant that we get from Energy Kinetics, which we have good success with.
  • EddieGEddieG Posts: 150Member
    edited April 2011

This discussion has been closed.


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