Water heaters and unions

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by Agu, Jun 20, 2009.

  1. Agu

    Agu New Member

    Messages:
    66
    Location:
    Tampa, FL
    My older home has a water heater I've considered upgrading to a more efficient model. After checking out the current model it appears this house is on it's third water heater already, both hot and cold have two coupling soldered in line. In fact there's no room to add another coupling without tearing into the wall to access virgin copper.

    So my question is, since water heaters need to be replaced why aren't they installed with unions ? I'm sure there's a logical reason but I can't figure out the logical reason ;).
  2. Mario

    Mario Master Plumber

    Messages:
    18
    Location:
    Kansas
    Uniform Plumbing code 2006 does require unions on water heaters.

    Forget soldering old style copper unions and di-electric unions with all their plastic parts and joining surfaces to worry about keeping clean.

    Unsweat the last coupling, clean the pipe and use a sharkbite flex connector.
    They count as a union and come in many sizes and lengths.
    An 3/4 sharkbite X 3/4 FIP will thread right onto the nipples coming out of your brand new Water Heater and push right onto bare 3/4 copper pipe with no soldering.
    Last edited: Jun 20, 2009
  3. Gary Swart

    Gary Swart In the Trades

    Messages:
    7,360
    Location:
    Yakima WA
    Local codes vary, but in many places water heater connections are made with flexible copper tubing. These come in various lengths and have female screw connectors on each end so it is quite simple to connect different sizes of heaters without changing pipes except for new flex pipes. Some places require solid connections, so this would not be legal in those cases. Check your local codes.
  4. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,837
    Location:
    Cave Creek, Arizona
    unions

    The logical reason is probably that the heaters were installed by DIYers who did not know any other way to do it. The way they did it was probably the worst way, and maybe the most difficult.
  5. Agu

    Agu New Member

    Messages:
    66
    Location:
    Tampa, FL
    Thanks, I'll check local code. The sharkbite sounds like the best option.
  6. Cass

    Cass Plumber

    Messages:
    5,980
    Location:
    Ohio
    Sharkbite makes a water heater connecter...a 3/4 MIP x 3/4 sharkbite...I never use unions I always use a 3/4 FIP adaptor...the galvy unions cause more problems by closing up or slowing flow due to rust buildup...
  7. SewerRatz

    SewerRatz Illinois Licensed Plumber

    Messages:
    1,705
    Location:
    Chicago, IL
    Here in Illinois a union is code. It does not have to be a dielectric union you can use a brass IPS union with a male adapter. Underlining in the code is by me.

    Section 890.350 Unions

    Unions may be used in the drainage and venting system when accessibly located above ground. Unions shall be installed in a water supply system within 5 feet of regulating equipment, water heaters, water conditioning tanks, water conditioning equipment, pumps, and similar equipment which may require service by removal or replacement. Where small equipment may be unscrewed, only one union shall be required.

    a) Drainage System. Unions may be used in the trap seal and on the inlet and outlet side of the trap. Unions shall have metal to metal seats except that plastic unions may have plastic to plastic seats.



    b) Water Supply System. Unions in the water supply system shall be metal to metal with ground seats, except that plastic to metal unions may utilize durable, non-toxic, impervious gaskets. Unions between copper pipe/tubing and dissimilar metals shall either be made with a brass converter fitting or be a dielectric type union.
  8. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,837
    Location:
    Cave Creek, Arizona
    heaters

    Here, almost all heaters are connected with flexible copper heater supplies which have both union and dielectric functions.
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