A package unit is a self contained piece of equipment designed for roof mount or sidewall installation. The equipment contains the complete heating and cooling system and comes ready to connect the ductwork. Package units are configured with openings in the bottom panel and a side panel for connecting ductwork. The unit is delivered with covers installed in place over the duct connections and the correct set of covers will be removed for installation depending on if the unit is to be ducted through a curb or sidewall.

When mounted on a flat roof it is very common to install the unit on a roof curb. The curb is mounted to the roof and flashed to make it weather tight. The roofing and decking in the center of the curb are removed to gain access to the interior of the building. The curb is constructed to be the same size as the unit so the unit will sit squarely on top of  it. Cross pieces are installed at the top of the curb to match the duct connections on the bottom panel of the unit. The ductwork is fabricated to drop in from the top of the curb with a 1″ lip folded out to rest on the cross pieces. The top of the curb is thin covered with a 1″ foam strip acting as a gasket to seal in the air flow. The unit is then set in place on the curb and ready for field connections for electric, stat, and gas if used.

When used as a sidewall installation the unit will be installed on a pad or some type of stand. The ductwork will connect to a sidewall on the unit and a return and supply duct will be installed from the unit through a sidewall in the building to connect to the building duct system.