Dielectric Union Application

Discussion in 'Plumbing Forum, Professional & DIY Advice, Tips & ' started by chuck b, Apr 6, 2011.

  1. chuck b

    chuck b sea-bee

    Messages:
    75
    Location:
    levering, michigan
    Should I install a dielectric union between the water well source pipe which is galvanized and the new copper which i will install? The entire small cottage is plumbed in glavanized at present. Cannon do much about the galvanized supply linie. Thanks.
  2. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,519
    Location:
    Cave Creek, Arizona
    Your real question should be, "will a dielectric union do any good". Inspectors would require a dielectric for every steel to copper transition. The problem is that a dielectric union is "cosmetic" and looks good for the inspector but does very little to prevent electrolysis. A 6" brass nipple is probably more effective.
  3. SacCity

    SacCity In the Trades

    Messages:
    189
    Location:
    Sacramento, CA
    I agree 6" brass nipple is a better way to go.
    The distance between the copper and the Iron is too short in a dielectric union and you end up with a lot of build up right at the joint.
    I've had to replace a number of them to resolve water supply issues.
    Michael
    Last edited by a moderator: Apr 6, 2011
  4. Terry

    Terry Administrator Staff Member

    Messages:
    14,915
    Location:
    Bothell, Washington
    A third vote for the 6" brass nipple. The City of Bellevue plumbing inspector requires the 6" brass nipple.
  5. chuck b

    chuck b sea-bee

    Messages:
    75
    Location:
    levering, michigan
    Further question on 6" Brass Nipple and Dielectric Union.

    A 6" brass nipple? Be patient. Could you explain in detail the assembly please? How is the 6" brass nipple connectetd to the galvanized and the copper at each end? Is it readily available at a Home Depot, or do I need to go to a plumber's supply house?

    Still use a dielectric connector? What method is used at each end to connect to the 6" brass? Do use use a dielectric union at each end as i go from copper to brass to galvanized. Appreciate the advice!




  6. chuck b

    chuck b sea-bee

    Messages:
    75
    Location:
    levering, michigan
    Hi Terry,

    what a good chance to thank you for this great site. so helpful. would this wisdom also apply to a water heater connection and be helpful in reducing buildup? Again, thanks...this is such a great enjoyable site. jsut bought this wonderful cottage (650 sq. ft.) on a nice lake just south of the Mackinaw bridge in northern michigan. doing a lot myself to save $$$. this is so valuable. chuck b
  7. cacher_chick

    cacher_chick Test, Don't Guess!

    Messages:
    3,244
    Location:
    Land of Cheese
    A female fitting is installed on the ends of both the galvanized and the copper pipe, and the 6" threaded brass nipple connects the two together. Threaded brass nipples are available at any reputable hardware/plumbing store. This IS a dielectric, and accomplishes the same thing as a dielectric union, only better.
  8. chuck b

    chuck b sea-bee

    Messages:
    75
    Location:
    levering, michigan
    Just want to be sure...you are suggesting a female fitting made of copper for the copper supply line to the cabin end, and a GALVANIZED femail fitting at the water well galvanized end, sith the 6" brass nipple in between as a sort of elongated dielectric union? Have noticed that the dielectric unions that i have installed on a water heater, have a plastic liner in them...is that a problem not being in the brass nipple? also, would this arrangement also be a better connection for a water heater as well?
  9. dlarrivee

    dlarrivee New Member

    Messages:
    1,172
    Location:
    Canada
    Pretty sure you'd need a union somewhere...
  10. Basement_Lurker

    Basement_Lurker One who lurks

    Messages:
    668
    Location:
    Victoria, BC
    Only the real cheapo water heaters don't come with unions factory installed. Any reputable brand will supply factory installed galv nipples which are lined with plastic...that's what you want. If you don't have those, then brass ones are a good substitute. You can adapt however you want from that point...be it hard piping with copper, or using one of the many variations of flex connectors.
  11. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,519
    Location:
    Cave Creek, Arizona
    quote; Only the real cheapo water heaters don't come with unions factory installed. Any reputable brand will supply factory installed galv nipples which are lined with plastic...

    1. I have NEVER seen a water heater with unions factory installed.
    2. Apparently you have never seen "dielectric nipples" which have delaminated with rust between the plastic and steel..
    3. the idea is to get separation between the two disimilar metals by using a material which is between them in the Noblility scale. Brass is that material when it comes to steel and copper.

    [​IMG]
    Last edited by a moderator: Apr 12, 2011
  12. Basement_Lurker

    Basement_Lurker One who lurks

    Messages:
    668
    Location:
    Victoria, BC
    1. Whoops, by factory installed unions, I meant factory installed nipples.
    2. You are correct, I have never seen laminated nipples suffer from that much corrosion.
    3. I use dielectric flex hoses to make my transitions, however otherwise I use cast brass FIP adapters or tank tees when hard piping with copper, I'm sorry I wasn't more specific for your liking, heh.

    (whoohooo lucky post #666)
  13. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,519
    Location:
    Cave Creek, Arizona
    quote; I'm sorry I wasn't more specific for your liking, heh. (whoohooo lucky post #666)

    It was not to MY liking because I didn't want someone who did NOT know what you meant to get the wrong idea. And I also use dielectric flexs, but that is NOT what the original question was about.
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