I have a Powerware 5115 UPS which is great, but it's fan is too loud and never goes off.

http://powerquality.eaton.com/Products-services/Backup-Power-UPS/5115.aspx?cx=53

Can anyone recommend good PSU, similar to the one I have, but if possible, to not have any fans.

I've been using an APC Smart-UPS 1500 since 2005 (the 120V version). It's not fanless, but the fan does not run all of the time. Even when it's running, it's quieter than my tower so I don't even notice it.

It is currently in dire need of a new battery, though.

That's a monster Nice one.

Well, the fan shouldn't work always on mine, but for some reason it does.

I've talked to my friend yesterday, who runs an UPS maintenance company. Since he only has Eaton products, he will give me 5110 model for testing

http://powerquality.eaton.com/Products-services/Backup-Power-UPS/5110.aspx?cx=53

Also, since EATON bought MGE, this one seems good too:

http://powerquality.eaton.com/Products-services/Backup-Power-UPS/Ellipse-MAX.aspx?cx=53

I will get the 5110 model next week and the most important thing is that it has AVR which is automatic voltage regulation with buck and boost.

those replacement batteries can get expensive

If you don't mind replacing the noisy fan, I've ordered silent fans from http://www.dorothybradbury.co.uk/ several times in the past. Dorothy has been operating her business for many many years and hand picks the fans she sells after extensive testing for noise. If she doesn't have a particular size, she'll either source it for you or recommend another dealer.

Awesome service!

If you don't mind replacing the noisy fan, I've ordered silent fans from http://www.dorothybradbury.co.uk/ several times in the past. Dorothy has been operating her business for many many years and hand picks the fans she sells after extensive testing for noise. If she doesn't have a particular size, she'll either source it for you or recommend another dealer.

Awesome service!

Do they ship worldwide?