Water Softener recharge--Water Heater Pressure Relief???

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by danbuc7, Dec 9, 2008.

  1. danbuc7

    danbuc7 New Member

    Dec 9, 2008
    Whenever my water softener recharges overnight, the pressure relief valve on my water heater opens up. I usually wake up to a puddle of water on the garage floor. The water heater should be independent of the water softener recharge process, so I’m not sure how or why this is happening. But it happens like clockwork. Any ideas? :confused:
  2. 99k

    99k Radon Contractor and Water Treatment

    Aug 16, 2008
    Contractor of Radon Reduction, Testing, and Water
    Fairfield Co.,Connecticut
    I am guessing that you need a small pressure tank between your softener and HW tank to accomodate the necessary water expansion during the regeneration period.
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  4. Gary Slusser

    Gary Slusser That's all folks!

    Aug 31, 2004
    Wherever I park the motorhome.
    T/P valves open on high pressure or high temperature. A softener can not increase temperature but, if you have higher water pressure during the night than during the day, as most city water users do, and have a control valve that can cause water hammer as it goes from one cycle position to another during regeneration, that can quadruple your main line water pressure and slightly for a fraction of a second open the T/P. Many used T/Ps usually do not reseal when opened but, the softener also reduces water pressure during regeneration because it allows water to go to drain.

    For <$15 you can buy a recording water pressure gauge and put it on a utility sink faucet or outside faucet, turn the faucet on and leave it overnight and record the max pressure in your house. If it is over say 75 psi, you need a pressure regulator valve or to adjust or replace your old one.

    An expansion tank for the heater will accept out flow due to high temperature expansion of the volume of water filling the tank. It will not reduce pressure or temp so I'm not sure it will solve the problem without knowing the cause but it might treat the symptom.

    If you are on your own well, you have an expansion tank; your pressure tank.

    I suspect you already have but I'll mention this in case you haven't. You should check the floor around the heater every morning to make sure the leak is only on the night the softener regenerates because it would be very unlikely the softener is the cause of the T/P leaking.

    Softeners should be plumbed with 7-10' of tubing from their outlet to the inlet of a water heater. That's so during regeneration warm/hot water can't back feed out of the heater and get into the softener where it can damage the distributor tube allowing resin beads out of the softener into the water lines and fixtures.
  5. danbuc7

    danbuc7 New Member

    Dec 9, 2008
    more questions

    I am on a well, so I have a pressure tank, but it is not between my softener and my water heater. Can you please explain the "necessary water expansion during the regeneration period?"
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