Thats exactly my point.
I want to be completely positive, and enthusiastic about hot water, and its benefits.
If I cracked a customers window after enthusing about it, I'd feel I'd let them down.
There's one house I'm really keen to use my hot water on. Its a big house, with big panes of glass, but the have a serious insect poo problem ( they live next door to a stables, and never close there curtains at night). I would imagine I'd have the water pretty warm to soften, and remove the poo.
But I'm a little worried as to what's the highest temp I can safely, and confidently get away with.
I mean these panes as literally covered in the stuff. I normally have to use a scourer to remove it, and even that doesn't remove all of it, and thats before I WFP

I think the point Dave made about turning the flow down to a trickle is a good idea - and the one I'd probably use.
But I'd like to know what temp most folks will , lets say, being using next week, with the temp dropping.
Thanks