is the pump 40psi?
is that powerful enough to do 3rd floor windows. not though bout the backpack before but it looks a good bit of kit.
does any1 carry it on their back?
Yes, the pump is easily powerfull enough to do three-storey buildings. No problem.
The pump has four settings from a 'trickle' to a 'super-jet'. Setting number two is the normal setting to use for routine WFP work. But you can use it on number one to scrub a whole load of windows then return to rinse on setting number two.
I've tried carrying it on my back, but it was too heavy for me, and I'm no lightweight.
It works best mounted on a light trolley and/or used as a 'grab and go'. It's easy to attach a strap to the handles.