Fantech Inline fans don't have sone ratings (a measure of loudness), but that doesn't mean you'll hear them. This fan consists of four components. Two small grill housings that are installed at the ceiling, one fan that is installed in a remote location well away from the bathroom, and a "Y" adapter to allow both exhaust grills to share the one fan. Because the fan is not right at the ceiling, the motor noise won't be as loud, and the penetrations through the ceiling will be smaller than with a conventional bathroom exhaust fan.
This fan should be installed with at least 8 feet of insulated flex duct between the grills and the fan. Flex duct will not only help reduce the transmission of sound from the remote fan back to the bathroom, but it is often easier to install than rigid duct.
Two models are available. The PB230-2 is a 230 cfm fan, comes with two 6 inch square grill housings with damper, one 4x4x6 "Y" duct, and is designed for use with 4 inch flex duct between the grills and the fan and 6 inch duct between the fan and the outside exhaust vent. It is rated for use in wet locations.