Hi, I have two on board (20704s), one in the galley and the other in the heads. The one in the galley is 16 months old. The other one is @6 months old. I only turn them on when on the boat- otherwise it is a matter of natural ventilation (you can close the vent off if you wish). The motor on one is a little noisy, the other silent. Bought from Burnsco- more than happy with them.
Mike