Ductwork is composed of two parts, supply and return. Supply duct is attached to the outflow of the new system, delivering air to each zone in a home. The amount of air reaching each zone is determined by the size of supply ductwork connecting it to your system. Your dealer will help you determine the size of all the supply ductwork in your home.

The second part of the ductwork, the return duct, attaches to the inlet of the new system and draws air out of the spaces to be heated or cooled. Attached to the return duct is the filter. The filter should be placed as near to the furnace or air handler as possible. Ductwork can be either fiberglass or metal and must be properly sized in order to evenly distribute the proper amount of air to each room.

An HVAC system should:

1. Be properly sized to provide correct air flow, and meet room-by-room calculated heating and cooling loads.
2. Be installed so that the static air pressure drop across the handler is within manufacturer and design specifications to have the capacity to meet the calculated loads.
3. Have sealed supply ductwork that will provide proper air flow.
4. Be installed with a return system sized to provide correct return air flow.
5. Have sealed return ductwork that will provide proper air flow to the fan, and avoid air entering the HVAC system from polluted zones (e.g., fumes from autos and stored chemicals, and attic particulates).
6. Have balanced air flows between supply and return systems to maintain neutral pressure in the home.
7. Minimize duct air temperature gain or loss between the air handler and room registers, and between return registers and the air handler.
8. Be properly charged with refrigerant.
9. Have proper burner operation and proper draft.