Well, I know it's not a necessity for cleaning windows having hot water, but I prefer using warm / hot.
Like I said, I've got an immersion at the moment, had it 7yrs I reckon, and I have it on winter and summer coz I prefer the way it cleans. In fact, when I first fitted it, I only put it on in the cold weather to keep my hoses supple, but then I preferred cleaning with warmer water. It certainly takes off the bird poop and fly dots more quickly. Then I started upping the temp coz I thought it was better again.
So for me, I think I'd like the diesel heater for a bit more consistency with the temp.
I'm also getting older and would like to make work a little easier on the body.
Thanks for the inputs.
Nic.