I couldn't hear when they switched it on, because the room had a normal air conditioner. It's quiet. I think the Power Supply fan may be noisier, but it is certainly drowned out by the noise of the CPU fan. And in spit of the fact that it's described as a "Super Cyclone Blower" it doesn't blow air into the PC at all: it's an extractor fan, not a blower. And the picture is upside down.
The main point is that it extracts hot air from the server, and I can tell that the machine is running cooler, simply by the cooler air coming out of the PSU fan. So I guess a refund is no longer necessary.