In some existing homes, the ductwork may not be easily accessible, so motorized registers or diffusers can be used to control the individual outlets. Provided the duct system is properly designed and sized, noise problems should not occur. If they do occur, the solution is to by-pass the excessive air causing the noise. This can be accomplished by adding a SPRD to bypass from the supply to the return or to dump excess air into a dump zone. Heat pumps are a very popular form of heating and cooling in many parts of the country, and are just as easy to zone as a gas furnace with an air conditioner.
Heat pumps are also ideal for zoning because of their limited heating capacity.
A zoning system can limit the use of expensive auxiliary heat and optimize the heat pump's operation.