Grundfos Alpha pump promlems

I have a Grundfos Alpha pump, about 8 year old, but it has developed a problem that I have seen registered on a number of sites including this one a couple of years ago, but I haven't seen anyone post the answer. I have the exact problem as quoted by mike from guilford in April 2008. In fact these are his exact words "I hThe pump works, pumps just fine (I have c/w + hot water)... but the flow is not constant. I can only describe it as a pulse. The green voltage light fades in and out with each pulse from the pump. There are no rattles/bangs. Just the normal sound of the pump, except it's pulsating"
Mine has been like this for a few months, the trouble is that the pump is in a cupboard in my daughters bedroom and she can't sleep.

Does anyone know the answer as to what might be wrong and can it be fixed or I need to replace the pump?

If it is an Alpha 1 pump, then Grundfos have admitted these were a problem.

Can't see the need for a modulating external pump myself. Technology gone too far IMO.

gas4you said:

If it is an Alpha 1 pump, then Grundfos have admitted these were a problem.

Can't see the need for a modulating external pump myself. Technology gone too far IMO.

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Thanks Dave. I assume that it's an Alpha 1, it just says Alpha on it. DOes mean that to fix it I have to replace it? Do you have a recommendation?

The Alpha 1 has an automatic settings, and manual settings. If you look at the control knob, on the left it has a symbol like a volume control from a TV or radio (this is the automatic selection range), and on the right, from memory markings I, II, III. these markings are the manual settings like a traditional pump. Have you tried turning the selector to one of these manual positions? I think the problem you describe is associated with the automatic function.

stem said:

The Alpha 1 has an automatic settings, and manual settings. If you look at the control knob, on the left it has a symbol like a volume control from a TV or radio (this is the automatic selection range), and on the right, from memory markings I, II, III. these markings are the manual settings like a traditional pump. Have you tried turning the selector to one of these manual positions? I think the problem you describe is associated with the automatic function.

Click to expand...

My pump only has a knob that you can turn. It appears to be fully variable between low and high, but turning it in either direction doesn't make any difference. There doesn't appear to be any fixed settings. The label on the pump says: Type: ALPHA 15 - 60 130.

Sorry, my mistake, my memory is not so good after all. The manual settings are below the white spot at 9-o-Clock, the automatic range above it, but perhaps yours isn't the same as mine.