My 19 foot trailer has a Dometic a/c unit which seems to do a good job cooling the camper, but is extremely noisy. Some have told me that ANY rooftop a/c unit without duct work will be very noisy, but others have said the Atwood unit is a better solution. My dealer seemed puzzled when I asked about switching to an Atwood, which he said he could do for $500 total cost but added that he has had customers who wanted to change from the Atwood to a Dometic! I am hoping for some useful info on this forum. Thanks.