Thank you for contacting us with regards to your model 350 Humidifier. The replacement parts for this unit would be the same ones that originally came with your unit. We don’t offer alternate motors and fan blades. If you feel that your unit is operating at a higher noise level than when it was originally installed, you might look into replacing the motor. Fan blades don’t typically wear out. Also, this model can be ducted in applications where the unit isn’t in the space that it’s humidifying. Flexible duct will offer more sound dampening properties than rigid duct, and more distance between the humidifier and its discharge vent will also help. We would recommend that you contact either your installer or current HVAC service technician to discuss each option.
Please let us know if we can be of further assistance.