We do a fair few roof cleans using a small 5hp machine running (I think 1500psi/10lts min.) you can see it in the photo I have included
It runs cold, using a turbo and we find it does the best job without covering the garden in mess. I have used a 12inch FSC on a exstendable pole from a tower but now if the customer won’t pay for a spider lift we don’t do the clean.
I cannot comment if heat would speed things up but so far we have got good results using cold.
I have tried using heat on drive and patio cleaning and it made no difference, so much so I took the hotbox off the van