Electric Water Heater Expansion Tank - Bondiing?

Discussion in 'Water Heater Forum, Tanks' started by chuck b, Jun 28, 2011.

  1. chuck b

    chuck b sea-bee

    Jan 19, 2011
    levering, michigan
    Installing a new electric water heater in cottage. Have noted in plumbing how-to books, that an expansion tank was situated on the cold water line before entering the water heater cold water inlet.

    Is this a new requirement, and what is the benefit. Water heater will be on a well, not city water supply. It will have its own expansion tank.

    Also on gas fired water heaters, should you bond the hot and cold water pipes to the natureal gas pipe as well.

  2. Cookie

    Cookie .

    Oct 7, 2005
    Since your well has a bladder tank you shouldn't need an expansion tank, as long as the water heater is on the same line as the well.

    In answer to your second part, you should not bond the hot and cold water pipes to the natural gas pipe.
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  4. LLigetfa

    LLigetfa DIYer, not in the trades

    Feb 6, 2011
    NW Ontario, Canada
    If you have metal piping, it should be bonded to the electrical service ground. Unless there is a dielectric union insulating the hot side, it should already be bonded through the water heater. The gas piping should already be bonded at the service entrance. No need for additional bonding at the tank.
  5. hj

    hj Moderator & Master Plumber Staff Member

    Aug 31, 2004
    Cave Creek, Arizona
    I have a theory, that the hot and cold SHOULD be bonded together at the water heater, especially when di-electric unions are used.
  6. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Sep 2, 2004
    Retired Systems engineer for defense industry.
    New England
    As noted, the well's bladder tank should be able to handle any expansion as long as you don't have any extra check valves, you should not need it. But, some locales may require one. You need someplace for water to go when you have a closed system, and a check valve creates that. As long as the bladder tank is on the same side of the check valve as the WH, in theory, no extra one needed.
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