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Attic Central Heating Expansion Tank Overflowing

Discussion in 'Plumbing and Central Heating' started by jameslm85, 23 Apr 2013.

  1. jameslm85

    jameslm85

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    Hi,

    I have a first floor flat with gas central heating. There is a boiler in the kitchen, a hot water emersion cylinder in the cupboard. In the attic are two water storage tanks, a large one for cold water and a smaller one which I believe is a central heating expansion tank.

    Each of the attic tanks have white overflow pipes that poke out the roof. With the onset of Spring and milder weather, I have stopped using the heating system and just use the emersion for hot water. In the last few days, I've noticed that the overflow pipe from the smaller attic tank is dripping (about 1 drip every 10 seconds) and showing no sign of stopping.

    It seems coincidence this has co-incided with since I've stopped using the central heating system.

    I have heard of remedies when the larger water tank is dripping by running the bath and adjusting the float arm, but how would I fix this for the smaller tank?

    Any suggestions appreciated.

    Many thanks,

    James.
     
  2. PlumbGas

    PlumbGas

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    go into the loft and see if the water is dripping into the tank from the float arm, if yes lift the arm gently, does it stop, if no replace it or call a plumber,
     
  3. jameslm85

    jameslm85

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    So lifting the arm slightly will cease any more water entering the tank?
     
  4. PlumbGas

    PlumbGas

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    Nope, it will tell you if the float arm is knackered which i am sure it will be, does it stop dripping ?
     
  5. jameslm85

    jameslm85

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    Okay I've been up into the loft.

    The heating expansion tank was full just to the point where a tiny bit of water was covering the opening of the outlet pipe.

    I tried lifting the arm as PlumbGas advised. I tried lifting the arm slightly, but it did not have any movement give in it. It was as if it was at its maximum height.

    There was a pipe above the tank which looks like where water comes into the tank, but no water was coming out of that pipe at all.

    Does it sound like my float arm is broken? Anything else I can try?

    Many thanks,

    James.
     
  6. Armo74

    Armo74

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    Take some of the water out the tank with a jug and put it in a bucket.

    There should only be about 4 inches of water in it anyway.

    This will give you more movement in the arm and should allow you to test the float valve.
     
  7. PlumbGas

    PlumbGas

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    Fairly sure your float arm is nackered,
     
  8. jameslm85

    jameslm85

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    What would happen if I removed a litre of water to slightly lower the water height? Or would the tank just refill to the original height again?[/img]
     
  9. jameslm85

    jameslm85

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    I took a picture of the tank:

    [/img]
     
  10. mogget

    mogget

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    That float is coming up far too far, the valve should cut off the water once there is 4 inches or so in the bottom of the tank. I suspect you will need a new float valve.
     
  11. picasso

    picasso

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    If you can turn off the supply to the small tank, if it still overflows you could be looking at replacing your hot water cylinder.
     
  12. gigz

    gigz

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    As said take water out until the level is about 4", if water starts dripping from the floatvalve carefully bend the arm so the floats in the water and it stops dripping, if it does'nt you need to clean/replace the washer/valve.
     
  13. jameslm85

    jameslm85

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    I've taken out some water, and the drop in water level did not open the valve to refill the tank. The dripping has stopped. So far so good.....
     
  14. mogget

    mogget

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    I'm hoping that doesn't mean the coil in the cylinder is holed... The water came from somewhere, if it's not getting in through the float valve, it must be coming from somewhere else.
     
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  15. Nige F

    Nige F

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    Irrespective of what`s knackered you need a new Part 2 Half inch float valve and float in place of that old one - the overflow pipe is too high through the cistern wall and you could get that :mad: water drawn back into the mains , Also a part 2 is much easier to adjust the water level ;)
     
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