Two window panels are mounted vertically in a frame and open by sliding vertically. They are controlled by traditional weights and cords or by spring/spiral balances. The use of spring balances allows the easy removal of panels for cleaning or painting. Air circulation is easily controlled by adjusting the sliding panels to suit.
As the panels don’t project, double hungs are great for applications where the operable components of the window unit are not allowed to project passed the wall, or where a projected panel could become a hazard.