Then, the system can be used only when the room is occupied and that can save on your utility bills.

There are several types including those that use electric strips to provide heat as well as those that use a hydronic coil, and those that have a built-in gas burner.

Most brands offer packaged terminal heat pumps which reverse the flow of refrigerant to provide heat when necessary.

There are also both vertical and horizontal models and your selection of type will depend on your own application. The vertical models typically are located in a closet that has an exterior wall while the horizontal type can be placed in any external wall.

The system itself slides into a sleeve that is installed in the wall usually during construction. To put the units in an existing structure, there will need to be some changes made to the wall structure for the sleeve.

The units have all of the heating and cooling components as well as the electronic controls built into a chassis that slides out for easy maintenance and repairs. They can either be plugged into the proper receptacle or hard-wired to provide power. They should usually be placed on their own individual electrical circuit.

Before you purchase one of these units, you can check out our reviews page. There, we compare the brands and rank them from a repairman's point of view.