Funny ya say that, i could have sworn (at the time i was looking) that the ones i saw over in the US for about $15 were
good for 40,000 hrs, i cant find them now, well, i can find some but dont state lifespan, i am still very happy with my
few quids worth of fan, a normal PC fan used in this way in the UK climate should be good for at least 2 years.
Having said the above, gimmie a minute to check sommat...
Ok, i built a stevenson screen back on 2008, i added fans to it due to backing on to shrubs, these fans were normal 80mm
pc fans, they were shielded bit more from the main elements due to the size of the screen but from 2008 to 2013, only 1
fan fail and it would still run if i tapped it, when i was mentioning lifespans above, i was being very conservative cause i couldnt
remember what year i built the screen.
It is a gamble though, i do not believe many of these fans are meant to run 24/7 anyway, but as Edouard needs reliability then
spending extra will guarantee a bit longer, although, PS Edouard its the humidity that gets at the fans mostly that and pollutants