Incredibly STUPID and DANGEROUS, as depicted laying on top is a fire hazard.
DON'T DO THIS. This article should be removed for suggesting potentially deadly activity.

The top of an oil room heater typically reaches a temperature around 130°C (266°F), 

A typical PC fan can operate within a temperature range of around 40°C to 65°C (104°F to 149°F)

THE FAN WILL FAIL AND LIKELY CATCH FIRE.

The melting point of a "PC fan," which is typically made from polycarbonate (PC) plastic, is around 295°C to 315°C (563°F to 600°F). 
So the plastic won't melt strait away until it catches fire.

Use any normal fan blowing on the heater from a cool safe distance, from the SIDE.
DONT EVER PUT ANYTHING ON A HEATER.
YOU WILL DIE.

It's a bit strange to criticize the lack of supporting evidence for the efficiency enhancement claims as this is common knowledge and is widely applied by plenty of people (and 5 minutes of googling nets you plenty of supporting evidence). The are many similar solutions like this available commercialy (at least where i live) that do the exact same as this. Active convention increases the efficiency of heat transfer from the radiator to the air which increases the efficiency of the system overall.

Noctua themselves haven't given information on why this works, but it does work.

A condensing boiler is very efficient at heating up water at a low temperature. Normally, if you lower the temperature you're gonna heat the room up less so you either need a bigger radiator, or something to extract more heat from the colder metal. A bigger radiator IS in-floor heating! Think about it, instead of the small thing attached to a wall, the whole floor is the radiator. That's why it's more efficient.
Forced convection is the other solution. In other words, a fan on the radiator. No need for it to be a noctua but noctuas are nice :D

TL;DR: it's actually a viable solution if you have a condensing boiler and traditional radiators. Put a fan on it, and lower the temperature of the heating water by a lot, to like 35-40C. Same amount of energy in the room, but the boiler is more efficient.

Quote from: Swizzy on January 24, 2025, 21:45:16

Quote from: gjbkgjb on January 24, 2025, 16:56:18In the photos the fans aren't connected to a power source. Does that mean that it's enough to just put it on the radiator? :-)

Do you think every product you've ever seen not physically connected to an electrical outlet works via magic or something?

Have you ever heard about sarcasm? If that's a product presentation I was expecting them to show a PSU-like device to power them

Quote from: gjbkgjb on January 24, 2025, 16:56:18In the photos the fans aren't connected to a power source. Does that mean that it's enough to just put it on the radiator? :-)

Do you think every product you've ever seen not physically connected to an electrical outlet works via magic or something?

In the photos the fans aren't connected to a power source. Does that mean that it's enough to just put it on the radiator? :-)