They're away from home for a couple of days, I'll ask them when they come back.
I have, today, received and installed the Hub 3 with the same results as described above. I hope the power saving will start working after some days. I can also pull the mains plug on the Hub 3.
Just to add my 2 penn'orth. I too installed Home Hub 3 yesterday and the automatic powersave is not working. Upon contacting the Helpline by phone (the chatline was useless, is this normal?) I was told that the firmware has been updated and the automatic powersave feature has been disabled. I was told that this is because there have been too many instances of the hub not coming back to life from the sleeping mode, when needed.
The guy apologised that the User Guide didn't reflect the new non-featured hub 3 and will pass it on.....
Being a sceptic (does it show?) I've no idea if this is true.