That is on about 1.8/2.0 LPM .
It’s not on that from the start though , that 71 was at the end of the day , the heater was being fed with recirculated water that was left in the tank .
I have found that normally from fire up I can raise the tank water temp by 35*c , normally 10*c in the tank jumps up to 45*c , then if all the hose is out 10*c is lost giving 35 at the brush head which I feel is ample in frosty weather (No broken panes) .
The temps rise quite rapidly , I find myself running at 75% power once the tank is half empty .