If installing a heat pump in an existing home without an existing heat pump or air conditioner, ductwork may need to be enlarged. Heat pump systems generally require larger duct sizes than other central heating systems. For proper heat pump operation, air flow should be 50 to 60 liters per second per kilowatt-hour or 400 to 500 cubic foot per minute per ton of cooling capacity. Fans and compressors make noise. Locate the outdoor unit away from windows and adjacent buildings.
Some units also make noise when they vibrate.
You can reduce this noise by selecting quiet equipment or by mounting the unit on a noise-absorbing base.