Quiet pump for gravity hot water

[David Hearn]

Having successfully fitted our mono mixer tap to our gravity hot water system (and mains pressure cold water) I'm considering adding a pump to the hot water system.

The flow to the tap is adequate and I'd be happy with it to stay like that - but we also have quite low pressure to the bath, which we've lived with for nearly 3 years, but it would be nice to have it fill a little quicker.

The water tank is in our kid's bedroom, and therefore we don't want any pump which might make significant noise. Silent would be ideal. We're not looking for wonderful performance - just a reasonable increase in pressure - I'm hoping that will mean we can do with smaller/quieter pump.

So, can anyone recommend a very quiet pump suitable to increase the hot water flow to taps. I'm not looking to replace any of the pipework coming directly out the tank (surrey flanges?) - rather just cut into the existing pipework after it has left the tank. At present we have no intention of using it with a shower (would require bathroom re-fit which we've no desire to to for a long time) - so this might help in giving an idea of the pump needed.

Many thanks

D

[Christian McArdle]

I've heard that the Grundfos Home Booster UPA 15/90 is quieter than most. No direct experience of it, though.

Christian.

[David Hearn]

Thanks for that - sounds like the sort of thing I might be after.

Looking at the specs, it says: "Typically adds between 0.5 bar and 0.75 bar pressure to the existing inlet pressure".

Any idea what that means in practice? Our house is a 1930's semi with quite high ceilings. Cold tank is in loft across joists (not raised). Hot tank is on 1st floor, on the floorboards. Bathroom sinks are on same floor as hot tank (with all hot pipework running through floorboards). Kitchen sink is on ground floor.

I don't remember the heights of the ceilings etc - but 2m might be about right. This therefore means I might have 1.5m head (from cold tank to tap) in bathroom and maybe 3.5m of head in kitchen.

I don't know what the conversion is between metres of head and bar, and therefore whether 0.5 to 0.75 bar increase is significant.

Thanks

D

[Christian McArdle]

1m is almost exactly equal to 0.1 bar.

Most single impellor pumps add between 1 and 2 bar, but are far noisier. I suspect this pump will meet your requirements. It will be a little puny for a shower, but a massive improvement. Upstairs, you'd go from 0.1 bar to 0.85 bar, which most will find perfectly acceptable, but not impressively so.

Christian.

[Rob Morley]

How the pump is mounted can be as significant as the noise it makes to start with - if you mount it securely on a heavy concrete block, sit that on a sheet of foam and make sure the flexible connectors aren't pulled tight then much less vibration will be transferred to the structure. You could also place sound-damping material inside the cupboard, but don't enclose the pump or it may overheat.