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?