Really large quiet fans?

[cheater]

Hi guys,
this might be a bit odd for this forum, as it's not about building a silent PC, but it's still about silent fans. I'm a huge fan of silent PCs and I've known SPCR since the very beginning, so I thought I'd ask this... what are the most silent large fans that you know?

This might be of use to people building a water cooling set up. I'm building a water heating setup... I'm trying to build some home heating automation, and I'd like to put fans on my radiators to spread their heat more evenly across my home. I want the heaters to be more efficient and to equalize changes in the temperature outside much faster than they do now. I'd like them to be very quiet, especially when i'm sleeping... so I hope someone here knows good ones to try out.

Given what i've seen from electrical radiators, I guess a centrifugal blower would be the best: one that takes air in through the hole on the side and puts it out through its fins with a shroud to control that it'll only blow in the direction of the radiator.

However, if you think a large axial fan is the best or the most quiet, please post about this. There's space in front of the heaters (at least most of them) to add axial fans. The radiators are all roughly 60 cm * 60 cm, or 23" * 23", some are a bit bigger, some are a bit smaller. They're all roughly 8.5 cm or 3.5" thick.

The fan's volume capacity doesn't have to be very high - the key here is silent. Anything is much better than nothing, as we all know from air coolers. If I install the fans / blowers and they aren't strong enough, I can still install other ones.

Thanks!

[Olle P]

Centrifugal blowers are the most noisy type, so I'd say that option is out.
When axial fans grow in diameter the wingtip speed also go up, so larger fans (>0.5m) become more noisy.
My suggestion would be a side blower. These can be made long and run fairly quiet while generating a "wall" of streaming air. Something like this one.

[cheater]

Hey, actually that's the kind I was talking about in my original post. You can often find them in electrical heaters. What is the difference between a side blower and a centrifugal fan?

[cheater]

I'll check out side blowers, that's a great idea, thanks. Any ideas what sort of CFM I should be looking at? I'm not sure how to calculate this.