i got the idea from a guy near my local work who does it,said he didnt lose a day last year and it was bad i was off for over 5 weeks,fair enough he didnt do as much in a day i would normally do with wfp,but im wanting hot water system set up(well the l5 system to get me started)so if i have to do it for a few weeks till it is delivered i have hot water to help me reclean them,so thinking of doing it,so done it on the nursing homes and when i went inside windows were fine