I was accused of cracking a double glazed unit not with hot water i might add but accused none the less, im quite a handy chap so replaced it my self, the unit itself was set in wooden frames ant when i got the old unit out it was quite clear to me that the unit had actually ben damaged by the installer he had hammered one of the pins through the wooden beading and just caught the edge of the glass and caused a very small crack which under neath all of the crap of this 1st clean went undetected, it was then that the custy accused me of cracking it, when i showed the damaged unit to the customer afterwards she poo poo'd my findings and sacked me as her window cleaner, so i only ever got to do 1 clean ( a 1st clean ) that job actually cost me money.