I have a heated system nearly the same as this.
Only problem is warm water freezes quicker than cold once on the windows or on ground.
So you may be able to work but the water freezes on the glass especially on conservatories or rooms with no heating, its worse on double glazing cos the outside panes don't get warmed from inside the house.
So although you can work without your equipment freezing up and your hands stay nice and warm you might come unstuck when customers cant see out of their windows till it thaws again.
Hope you get on okay