Supply and return
Supply ducts deliver conditioned air. Return paths bring air back to the equipment. A missing or restricted return can create pressure differences and rooms that never reach a comfortable temperature.
Leakage and insulation
Ducts running through attics, crawl spaces or other unconditioned areas can lose energy through leaks and inadequate insulation. Sealing and insulating accessible runs may improve delivered performance.
Size and routing
Undersized ducts or sharp transitions can raise resistance and noise. Oversized equipment can also cycle poorly. The design should connect room loads, equipment airflow and the duct layout.
Before replacing a unit
Have the contractor inspect the existing distribution, measure airflow where appropriate and explain any duct changes in the written scope. A new condenser cannot repair a poor air path.
Sources and further reading
- US Department of Energy: Heat Pump Systems
- US Department of Energy: Central Air Conditioners and Heat Pumps