The Heatfan is extremely silent, underneath 20 dB. To give you an impression how much this is. A ticking clock makes about 30 dB noise and a falling down tree leaf about 10 dB. So the Heatfan will meet somewhere in the middle. And shouldn't be audible in any situation.
The Heatfan uses about 1 Watt-hour per year. This means about £0.14 per year!
The Heatfan components are based on minimum lifetime of 50.000 hours. With 50% continuous usage, it's 11,5 years!