A 2- to 5-ton packaged unit is available from several manufacturers. Lennox makes a self-contained unit that can be mounted on a slab or on the rooftop. See Fig. 16-1. This one is designed for the residential replacement market. The compressor, control box, filter, condenser coil, and evaporator coil are in one package. The blower is also located in the package. The only component inside the building is the ductwork. Return air enters in the lower opening through the evaporator coil and is discharged out through the top opening.
One of the advantages of a unit of this type is its completeness. It comes ready to connect to the ductwork and the electrical outlets. The blower is located outside the house. The inside noise is that of the air moving through the ductwork. The air filter is also located outside. It is a vacuum-cleanable type with polyurethane coating. It is coated with oil to increase efficiency. If the filter is washed, it should be reoiled.
Up to 58,000 Btu can be added with an optional field-installed heating unit. If electric heat is desired, it is possible for this type of unit to heat and cool, using the same ductwork. Figure 16-2 shows typical unit installations.