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joe0508's avatar
joe0508
Explorer
Apr 21, 2014

hot water dispenser

I have one of those instant hot water dispensers located on my kitchen sink.The other day i hooked it up.I plugged it up and left my hot water heater on.A while went by and i noticed my hot water heater was leaking on the outside.Is there a rule that you cant have the hot water tank on at the same time as the instant hot.

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  • joe0508's avatar
    joe0508
    Explorer
    Apr 21, 2014
    I will have to check it out more but what i did do is right after it happened i let it cool and turned the pump back on and the tank filled and the pump stopped.I turned the hot water heater back on to see if it would work after i let it cool.The water heated up and no steam.I could not do much because i ran out of fresh water in the tank and it was raining hard outside.I didnt plug the instant hot back,I was afraid too.I am away and plan to check it out more when i get to it.I guess i will leave well enough alone if not using the instant hot fixes things.
  • Dutch_12078's avatar
    Dutch_12078
    Explorer II
    Apr 21, 2014
    It might be the most common water heater "drippage" problem around, that of the air space in the tank being absorbed, causing the expanding water to push out the relief valve. A simple drain and refill will cure that problem.
  • rockhillmanor's avatar
    rockhillmanor
    Explorer II
    Apr 21, 2014
    Not to mention the more serious problem of the thermostat going on the blink which will cause it to trip the relief valve and leak down the side.

    Mine did just that and the whole side of the MH got so hot you couldn't touch it.
  • skipnchar's avatar
    skipnchar
    Explorer
    Apr 21, 2014
    I suspect that the tow things are unrelated. Where is the HW tank leaking from? A leak around the plug may just need a new plug (if it's an Atwood heater and those should be replaced every year or two anyway) and if it's leaking around the pop off valve, it probably needs a new valve. If it's leaking around the metal plug of a Suburban heater, you may only need to clean the threads and add some teflon tape around the plug. Also consider NOT leaving the plug out when the heater is not in use because that will cause corrosion around the threads. Be sure you reinstall plugs of EITHER brand when the tank is empty.
  • wa8yxm's avatar
    wa8yxm
    Explorer III
    Apr 21, 2014
    I would not guarantee a 3 valve system won't have a check valve, Nearly all RV water systems have check valves (I once designed an RV water system .. No, I take it back it too had check valves, 3 of them.

    There is a check valve on your city water inlet.
    There are two check valves in your water pump.

    And on many water heaters, no matter the bypass system, there is a check valve on the outlet.

    NOW: IF that check valve exists, then pressure can not back up from the Instant Hot dispenser to the water heater.

    To the original poster.

    You may have lost the air cushion on the water eater.. Part of the contents of the heater is a large Air Bubble that allows for expansion of the water as it heats.

    To re-establish, cut off water flow to the water heater (Bypass valve or simply turn off water pump and DISCONNECT from city water or turn it off).

    ALlow water heater to cool

    Remove drain plug and manually open TPR valve at to

    Let drain


    Relace plug, close TPR, restore water pressure.
  • joe0508's avatar
    joe0508
    Explorer
    Apr 21, 2014
    joe0508 wrote:
    joe0508 wrote:
    Old-Biscuit wrote:
    Next time it happens.......
    Feel the water line on instant hot. If it's hot then you'll know

    If it isn't then you'll know other problem exists.

    Process of elimination as you are there to check things out.
    So what you are saying is that the hot water is mixing with the cold water?causing the hot water heater to overheat.
    If it is hot hot how do i go about installing a check valve?
  • joe0508's avatar
    joe0508
    Explorer
    Apr 21, 2014
    joe0508 wrote:
    Old-Biscuit wrote:
    Next time it happens.......
    Feel the water line on instant hot. If it's hot then you'll know

    If it isn't then you'll know other problem exists.

    Process of elimination as you are there to check things out.
    So what you are saying is that the hot water is mixing with the cold water?causing the hot water heater to overheat.
  • joe0508's avatar
    joe0508
    Explorer
    Apr 21, 2014
    Old-Biscuit wrote:
    Next time it happens.......
    Feel the water line on instant hot. If it's hot then you'll know

    If it isn't then you'll know other problem exists.

    Process of elimination as you are there to check things out.
  • Old-Biscuit's avatar
    Old-Biscuit
    Explorer III
    Apr 21, 2014
    Next time it happens.......
    Feel the water line on instant hot. If it's hot then you'll know

    If it isn't then you'll know other problem exists.

    Process of elimination as you are there to check things out.
  • joe0508's avatar
    joe0508
    Explorer
    Apr 21, 2014
    Old-Biscuit wrote:
    Sounds like the 'instant hot' hot water backflowed into water heater causing the PRV to leak.

    A check valve on line to instant hot should solve that.

    Course I don't know how you have it plumbed.....


    It could have just been because you lost the 'air gap' in top of water heater tank.
    And when water heater made hot water IT caused the PRV to leak.
    To re-establish air gap
    Turn off water supply
    Open closet facet Hot side to relieve pressure
    Open PRV via lever.... (CAUTION WATER COULD BE SCALDING) when water stops flowing out let it snap closed
    Turn on water supply
    Close faucet


    ON EDIT:

    This is the same problem you posted about early.
    You also posted you have three valves on water heater......3 valve system don't use check valves.

    You need a check valve to stop backflow from instant hot
    Instant hot is tee off of cold side.How could it be back flowing?

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