If it helps at all I had exactly the same problem after attempting a clean install of Yosemite on a MBA13, inadvertently skipping from the the "download OSX" in Disk Utility: trying to reboot went straight to the - what I believe us termed - folder of death.
No further progress was made after connecting to Wifi, spinning globe and WLAN connection was all that was on-screen for ten minutes before the warning triangle displaying "apple.com/support 2002F" came up.
Lots of threads advise trying gigabit cables or installers on flash drives but, although I also have an iMac, wasn't convinced the MBA would recognise an ether connection as the adaptor would not be configured to a new machine, and didn't have the time or expertise to flash OSXinstaller without crashing another Mac.
Here's what worked, in summary: after five failures on my home network I took the thing over to my Dad's house and connected to Wifi there, which is VirginMedia cable and has 2 or 5 GBpS speeds, and - lo and behold - two seconds after connection straight to progress bar!
Another ten minutes and Disk Utility returned, a further twenty and Yosemite installed and I'm up and running with only Pages etc. left to complete!
My guess is that some ISPs don't connect very well to Apple's servers for reasons that remain a mystery to me, Talktalk at my house perhaps being one of them. I still don't know about trying with a faster Ethernet connection because I reckon if you've wiped a partition with OSX then you've wiped any configurations for cable cable adaptors too, if they're necessary and you had them in the first place.
Tthere's always Apple's brilliant and usually free back-up if it fails but five minutes on a better network did the trick for me.