A single hung window features a clutch assembly on the sides. The clutch assembly looks like a metal rectangle with a circular device in the center that attaches to a line. The line keeps the window moving smoothly as you raise and lower the window. With frequent use, the clutch becomes stuck and creates a jam. You might even notice that one clutch sticks, while the other moves, which causes the windowpane to sit unevenly in the frame. The line can also loosen or tighten, making it difficult to move the window.
A double hung sash window lets you move either panes or a single pane, giving you more design options. For example, you might hang a window-unit air conditioner from the upper part of the window, leaving you unobstructed views below. Single sash windows limit your options because only one of the panes moves.
One advantage to double hung windows relates to cleaning, especially on upper floors. To reach the outside for cleaning, you simply slide one window up or down, until you have access to that pane. Some double hung windows have a tilting design that lets you tilt the windows inside your home for cleaning. Cleaning single hung windows is more difficult because you can access only a part of the outer window from inside your home. Cleaning the window along the upper floors typically involves using a pressure washer or garden hose and ladder.
When properly maintained, a single hung window glides effortlessly along its track. Older windows often have a string that fits long a molded space and keeps the window moving. Even the slightest amount of debris can stop the window from working properly. The debris clogs the track and stops the window from sliding up and down. You must properly clean the track with a vacuum cleaner or dusting. If you use a vacuum, run the hose along the side of the window, removing any dust, hair or other debris.