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Thread: Mineral Deposits in Water Heater Inlet

  1. #1

    Default Mineral Deposits in Water Heater Inlet

    While re-piping the cold water supply to my Water Heater, I noticed that at the the dielectric union at the water heater was very clogged with rust and other minerals. This would probably partly explain the terrible hot water pressure I get in my house. It was almost totally clogged with rust and black gunk. I cannot remove the Male portion of the Dielectric union (that is screwed into the top of the water heater tank), as its in their pretty tight. Is there any danger in simply taking a screwdriver and breaking up the mineral deposits so they fall into the water heater... or should I put more effort into replacing the nipple/dielectric on top of the water heater?


  2. #2


    see attachments for some pictures to illustrate...

    Attached Images Attached Images   

  3. #3
    Master Plumber master plumber mark's Avatar
    Join Date
    Feb 2005
    indianapolis indiana - land of the free, home of the brave....
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    Talking mineral deposits

    Today I just charged someone $115 to come out
    and use my "hi tech" craftmen screw driver and hammer to
    rheem out the inlets like you are talking about...

    a hammer and screwdriver work great to get
    those deposits out of those nasty worthless dialectric unions.

    its usually worse on the hot side ,....so do both

  4. #4


    Great, thanks for the advice!

    Funny thing is I already replaced the hot side and it actually looked cleaner than the cold. Must have been the black iron coupling someone had inexplicably joined with the galvanized pipe I just removed from the supply side.


  5. #5
    In the Trades kordts's Avatar
    Join Date
    Oct 2005
    exurban Chicago


    Get an 18" or 24" pipewrench. remove the existing nipple and replace it with brass, or copper male adapter. If you have hard water, dielectrics act like a magnet for minerals and rust.

  6. #6
    Moderator & Master Plumber hj's Avatar
    Join Date
    Aug 2004
    Cave Creek, Arizona

    Default nipple

    if the union and nipple are that bad, removing the crud will expose the surface of the pipe to the water, and it has probably started to rust and will turn your water red or brown. Replace it.


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