Grundfos pump suddenly very noisy?

Discussion in 'Plumbing and Central Heating' started by Londoner, 4 Dec 2006.

  1. Londoner

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    Hi there wonder if anyone can help.

    We have an Ideal Classic boiler, non-condensing (not that new). All has been fine since we moved in a few months ago but recently there have been very loud noises coming from the area from the pump in the upstairs airing cupboard. The pump is set on Level 2.

    The noise is a bit like trapped air forcing its way through the pipe, or very high pressure water going through and it does seem to be centred on the pump (I know it might not be really, though, and acoustics can play tricks). It's loud enough to make you think the whole thing is about to explode!

    What I'm wondering why it would suddenly start making a noise now when it fine for the last few months? We haven't changed any of the heating settings, other than turning the thermostat in the hallway.

    To save on energy we don't have all the radiators in the housr on. 3 of them have the valve left in the closed postion. Is this a bad idea and is it anything to do with the noise?

    If not how can I stop the noise? Should I turn the pump switch down to Level 1?

    Any advice appreciated.
     
  2. ChrisR

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    Check there's water in the header tank, and that all the rads are bled of air. WHich size Cassic? Speed 2 is probably ok up to 50 or 60, may need speed 3 bigger than that.
     
  3. Londoner

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    Would the header tank be the small plastic tank in our loft, slightly larger than a toilet cistern, and not sealed shut?
     
  4. Londoner

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    I guess I should try bleeding the pump too? Just saw some older threads recommending that.
     
  5. Diyisfun

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    Yes it is
     
  6. Londoner

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    OK this has developed a bit...

    Checked the header tank. Level seems normal.

    Loud noises now start quite soon after we start either the hot water or central heating.

    Tried unscrewing the bleed screw on th e Grundfos pump in the airing cupboard - no air came out. Also swicthed the pump down to 1. This had seemed to temporarily ease the original noise before but now it's back with a vengence. Pic of airing cupboard below:

    [​IMG]

    In addition, the boiler overheat switch trips very quickly (its an Ideal Classic, non-condensing) and I have noticed that the front panel exterior of the boiler is very hot to the touch (is that normal?)

    So could overheating be causing the noises?

    Or is it the pump causing the overheating?

    Or is it neither of those?

    Any help appreciated.

    PS. I tried unscrewing the bleed screw on the Grundfos pump again just now, and no air OR water came out. Nothing came out at all and I undid the screw completely. Is that what's supposed to happen???
     
  7. dee dee

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    Hi there,
    It's dee dee here,
    I have just had the BG engineer round and I've just posted his prognosis. Not sure if it will help your situation but fingers crossed.
    Dee.
     
  8. ChrisR

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    New pump required, unless there's a load of trapped air or a blockage.
     
  9. Londoner

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    thanks all.

    ChrisR, would this explain the overheat switch tripping as well?

    Also, is there anything I can do myself re: air trapped in the system or is it time to get British Gas round? Like I said I tried the Grundfos pump vent screw and there was no rush of air or anything.
     
  10. scaby

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    blocked cold feed?
     
  11. Londoner

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    Hi scaby. Is this something I could check for and try to fix myself, or is it British Gas time?
     
  12. scaby

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    normally when the cold feed blocks, it can be very difficult to move ,if you follow the 15mm? pipe down from the f and e to where it joins a 22mm? pipe this is where it can block
     
  13. ollski

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    Do you have thermostatic valves on all the open radiators?
     
  14. Londoner

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    I *think* they are thermostatic. At least, they have numbers on them.

    But I should say that last night we tried the hot water only (no central heating) and it still made the noises, banging, overheat switch tripped etc.
     
  15. scaby

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    probably because the water level has dropped below the pump and there is no circulation of water
     

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