Can they be as efficient and keep a room as warm as the old fashioned under the window type?
I remember someone explaining to me that one of the ways the horizontal ones work, is that becuase they are set under windows, they heat up the cold air leaking in and that is more efficient than placing them on a wall without a window.
But these vertical ones obviously don't go under windows, so miss that bit of efficiency. How do they compensate? Are they as efficient?