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Failed capacitor on Grundfos pump?

Discussion in 'Plumbing and Central Heating' started by Odyssy, 3 Nov 2004.

  1. Odyssy

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    Conventional vented system, the pump isn't running. I've removed the vent plug and cleaned the debris out - shaft was turning freely. There is power at the pump and I've tried tapping it with a hammer.
    The only other possibility other than replacing the pump, is that the capacitor has died. The system has been noisy on start up occasionally over the last couple of weeks with hammering and boiling over into the header tank, although the pump usually started. The pump is a grundfos UPS 50-15x18. Any thoughts gratefully received. Thanks
     
  2. ChrisR

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    Measure the resistance of the windings, L - N, which shouldn't be zero or infinite. A £5 multimeter would do it.
    Cos I'm a smartarse I'd measure the capacitance of the capacitor:cool:

    They do fail, but yours is quite an old pump so probably worn anyway. Wilo's are bad for blowing capacitors, Grundfos not so often.
     
  3. Odyssy

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    Chris - thanks, you were right - capacitor dead. I've replaced the pump anyway and the improvement is quite amazing - the whole system is much quieter, the old pump must have really been on it's last legs. I don't think I even need to replace the boiler - no kettling! Yippee!
     

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