Silent central heating pump?

Our central heating pump is located in our airing cupboard, which is actually a conti-board cupboard in a bedroom (pre-existing when we arrived here) which is right next to where we put the spare bed. The bedroom it is in is actually our 1 year old son's nursery.
The problem is that the pump makes enough noise when it's running to be disturbing. We believe that this is what is waking our son quite early in the morning. We're experimenting with putting the heating/water on later - however this could be a problem in the winter, and also as we could do with hot water early one morning a week - although for now we can make do without.
The pump is a Grundfos UPS (15-50 I think) and has been here since we arrived 2 years ago. It doesn't look terribly old - however rest of the system was a *bit* dated - but not terribly (old boiler + signs of pump relocation). Consequently I don't really know how old the pump is.
The pump is on its lowest setting (1 of 3) and turning the pump up makes a lot more noise although I think part of it is that it's resonating around the pipework. The pump is mounted within a kind of vertical U before entering the cylinder (pumping downwards in the down leg of the U with what appears to be an air-valve at the top of the U) - consequently, the pipework can move a little - allowing it to resonate - although I don't believe the low speed noise is resonating as its only really noticable within the room, unlike the higher speed which can be noticable downstairs too.
What I'd like to know is if there is a particular make/model of pump which is quieter than this one. Relocating the pump is out the question, as is altering the pipework. I guess a new pump should be quieter just because the bearings are new - as would reducing the RPM, although I guess we can't really that unless the pump is physically larger to get the same throughput.
Can the orientation of the pump alter the noise? I know pumping downwards can be a problem for air - however that's how it was when we got there, and our boiler states it must have the pump on a particular feed/return so reversing the pump may be a problem.
Any ideas for a quiet pump replacement?
Thanks
David
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David Hearn wrote:

I changed my pump to pump up and at the same time used a cleaner and inhibitor in the system and after doing that the pump made so little noise that it was difficult to determine whether it was running at all.
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David Hearn wrote:

I think if you was to replace the pump you'd be pleasantly surprised; I did this only a month or so ago, and, despite some bloody-mindedness of the existing plumbing, it was a fairly painless job.
You might want to review my experience, here, first though...
http://groups.google.co.uk/group/uk.d-i-y/browse_thread/thread/97907942e735b18f/d385aebfda0dc02c?q=dodd+group:uk.d-i-y&rnum=3&hl=en#d385aebfda0dc02c
Mike
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I changed the same pump for a Grundfos Alpha a couple of years ago - far far quieter.
Get new valves at the same time - I couldnt get my old ones off ( even in the workshop afterwards).
I believe they appear on Ebay at regular intervals.
Robert royall at which net
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wrote:

the
The valves or Alpha pumps?
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wrote:

Alpha pumps royall at which net
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Fit a Grundfos Alpha. Electronically self-controlled so it only pumps when needed, it really is as quiet as you're likely to get.
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OK, I give up.
Can anyone tell me where to find mechanical drawings of the Alpha?
I've been through the Grundfos site, and their posh system has utterly defeated me.
It's only that space is a bit tight, and I'd like to check I can get the bulgy bit in.
Anyone know where there's a naccessible picture with dimensions please?
mike
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It's the same size as the 15/60. I seem to recall it had it's own site as well.

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The body may be, but I'm worried about the bolted on control unit
mike
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On 1 Jun 2005 09:57:14 GMT, mike ring

http://www.grundfos-www.com/alpha/frames_html.htm
The picture makes it look bigger than it is ! royall at which net
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I've just compared my Alpha with a Danfoss pump. To all intents and purposes they protrude the same amount - I doubt if you could make the three way switch on a standard pump much smaller anyway so I expect the 15/60 is the same as well.
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