IMO its not just that hot pure water removes the insect spots,baked on bird muck on frames and glass,sticky pollen,grass cuttings,leaves,snail trails easier.....also hot water gives a better flow to your brush,windows rinse easier and dry much quicker and much more manageable hoses all year round.....
you boys carry on with cold water if your happy with that....i really dont give a toss anymore.....
According to alot of stuff I have read online, hot water gives a better flow but cold water sheets better on surfaces.
Also using hot water on hot surfaces creates a higher chance of spotting as the water will evaporate much quicker and before all contaminants can run off.
I can honestly say daz that i did not notice hot removing snail trails any quicker then cold, windows do not rinse quicker especially in warm direct sunlight for the above reasons. In fact in very warm sunny days I dare you to inspect the bottom edge of the glass, look very closely and you can see the water dries too quick and leaves spotting along the bottom. I noticed this a few times, even when rinsing with a high flow and 0ppm water. It almost looked like dry steam marks.
I have been using cold again for 2 days now, yesterday on a big medical centre and today on a load of houses and have noticed no difference in speed, ease of cleaning, hoses were perfectly manageable and the finish was perfect. I know this because I cleaned the inside of the medical centre after doing the outside.
Im thinking more and more that the best water temp is actually just slightly warm, particularly as we agitate the surface with a brush, then hot is just not needed.
The temp currently in my tank is 20c, I'm thinking of just heating the water to around 35c in the tank as I think that is more then sufficient for what we need without the added faff of killing brushes, risk of cracking windows, spotting on hot days and very very cheap to do.
Ps I have the stiff supreme brush, it just feels awful on the glass plus its just too small for my liking. There just isn't enough choices in terms of brushes for hot water.