V8edd,
We've ran it on hot ever since getting it earlier this year, never broken a window due to temperature of water, we broke one in September but that was because he tripped whilst using a 60ft pole and smashed a georgian window on the third floor.
We ran it right through the cold spell at the beginning of the month, out at 06:30 on commercial work without any problems (touch wood!!!!)
I've got photos of the system and them cleaning but cannot upload them onto this site due to the size of them, if your email address is on your profile I'll try emailing them across to you.