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Hot water venting cold water header tank

Discussion in 'Plumbing and Central Heating' started by ANGLER, 6 Mar 2018.

  1. ANGLER

    ANGLER

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    Increasing issues. Hot water from the emersion tank venting into the cold water tank, causing the water to level to reach the overflow.
    Hot water only used for kitchen and bathroom
     
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  3. Daveydub

    Daveydub

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    Is your heating tank fed or sealed system?
     
  4. ANGLER

    ANGLER

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    The tank is a indirect tank. The tanks are only used for kitchen and bathroom tap use.

    We have electric storage heating system.
     
  5. Daveydub

    Daveydub

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    So nothing is connected to the coil in the cylinder?
     
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  6. oldbuffer

    oldbuffer

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    Assuming the hot water is heated only by the immersion heater (not by a boiler) then, if the hot water is extremely hot, the thermostat in the immersion heater may have failed, allowing the water to heat up too much. It then expands into the cold water storage cistern (CWSC), and will cause it to overflow.

    If it is this, then it needs fixing as a matter of urgency, or the CWSC could collapse and pour very hot water through the ceiling.
     
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  7. ANGLER

    ANGLER

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    Last night I replaced the Immersion element & thermostat.
    Yet again warm water was being expelled out the overflow on the cold water header tank.
     
  8. terryplumb

    terryplumb

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    There is a vent pipe that comes up and over the top of the tank ,and points down Into the tank ,is that where you have seen water coming from ? That's unlikely if you have just replaced the immersion element AND a new thermostat. Are you sure its not the float valve allowing water Into the tank when it shouldn't.?
     
  9. Daveydub

    Daveydub

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  11. terryplumb

    terryplumb

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    Do you have a mixer valve ,shower or tap ,that is fed cold from the mains. Possible cross flow into gravity hot water system ?
     
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  12. ANGLER

    ANGLER

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    Nothing connected to the coil
     
  13. ANGLER

    ANGLER

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    Haven't seen water at present emerging from the vent pipe, but the water being expelled outside is warm. Also contents of the cold water tank is also warm. Ball valve also replaced as a precaution.
     
  14. terryplumb

    terryplumb

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    Mains cold water is getting into the dhw system if nothing is coming out the vent pipe.
     
  15. ANGLER

    ANGLER

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    If this is happening, how can I prevent this?
     
  16. terryplumb

    terryplumb

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    Establish where the cross flow is and eradicate . common on single handle lever taps, thermostatic mixer valves on showers ,bath fillers ,etc pumped hot to shower and mains cold to same. Its a process of elimination really.
     
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  17. ANGLER

    ANGLER

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    Just let everyone know. The issue went away, when we upgraded our bathroom toilet. The previous toilet had an EYE wash attached, with a cold and hot water feed. The cross over must of occurred here.
    The toilet and upgrade was not done for this reason.
     
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