Ductless heat pump systems are sized to meet the heating and cooling needs of individual zones in the home. There is a great deal of flexibility when it comes to system sizing as one indoor unit can provide between different levels of heating and cooling depending on its BTU capacity rating. Some common capacities for indoor units are 9K, 12K, 15K, 18K, 24K, and 30K BTU. Units are sized to meet the combined load of all heating/cooling zones. More than one outdoor unit may be necessary for multi-zone systems.
Ducted heat pumps have an integrated backup heat source and are designed to meet the needs of heating your whole home. The ducts are sized to ensure efficient heat distribution throughout. Your installer will measure the BTU capacity of your home and help you choose accordingly.