Shutoff valve on hot side?

Discussion in 'Water Heater Forum, Tanks' started by frankjc, Sep 25, 2020.

  1. frankjc

    frankjc New Member

    Sep 16, 2020
    I am installing an electric hot water heater. Should there be a shutoff valve on the hot side? The instructions only show one on the cold. Not sure if its a good or bad idea to put one there.
    Thank you.
  2. Reach4

    Reach4 Well-Known Member

    Sep 25, 2013
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  4. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Sep 2, 2004
    Retired Systems engineer for defense industry.
    New England
    Generally, it's not needed on the outlet. One thing you should seriously consider if you don't have one, is to include an expansion tank. Heating water causes it to expand. If you have a valve on both sides and you turn a cold tank on, you could split your water heater if the T&P valve is defective. Regardless, an ET is code many places, and changing your WH is a good time to include one. While functionally, if you don't have a check valve in the water feed to your home, you may not 'need' one, it's not a bad idea as it will keep the T&P from opening in normal circumstances, and keep spikes from occurring in your water pressure during use making washing machine hoses, etc., last longer, too.

    If you're on a well, the pressure tank will perform that function.

    Most of the time if you need to work on the WH, you just shut the inlet off, drain the system, and go on with your life, so a valve on the outlet doesn't buy you much except complexity and cost...won't hurt, though.

    Make sure you fill and ensure there's no air in the tank before you turn it on, or you'll fry the upper heating need to purge the air by opening hot water valves upstairs until it runs free without any air...then, you can turn the WH back on. A WH element that gets turned on without water surrounding it will melt.
  5. frankjc

    frankjc New Member

    Sep 16, 2020
    I am just trying to decide if i should spend the time to install one,
  6. dj2

    dj2 In the Trades

    Aug 13, 2013
    Once I was replacing a WH,
    When I disconnected the hot line, the water came out and into the bucket, and came out. and came out.
    When it finally stopped, I installed a shut off ball valve on it.
    A time saver for the future.
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