An air handler installs in the home and connects to the ductwork to provide cooling or electric heat (optional) indoors. The air handler is completely preassembled, and consists primarily of a multi-speed fan, built-in evaporator coil and electrical controls. Depending on the model they can be installed vertically, horizontally or in a downflow application. If winter heating is needed, an optional electric heater coil can easily be installed into the air handler or ductwork.