there is what seems to be a complex internal cleaning process because the oil that is sucked up by the fan is collected in a internal collection unit. and there are other maintenance issues as well. do you do this maintenance on your own?? will vent a hood dealers do it for a price?? for those remodeling, Vent A Hood is just outstanding though the unit we have is so loud, you cant hear the phone. But it sucks up cooking oil like a dream.