Just park it on a hill and it will drain from the rear most duct. They are not waterproof. I used gallons of bleach water to clean mice dropping and urine odor in my ductwork. A wet vacuum got the solids out.
thanks for the replies....my wifes sister was visiting us when we were in Fla and we went out for dinner and she left the water run in the bathroom sink....came back to water running out the bottom of the motorhome. Pulling out the carpet and checking the floors, but wasnt sure about the furnace vents
Mine are all made of aluminum foil with a plastic liner and will hold water until either wiped out, drained or the water evaporates. OP's might be different, but being a FR product, I have my doubts.
thanks for the replies....my wifes sister was visiting us when we were in Fla and we went out for dinner and she left the water run in the bathroom sink....came back to water running out the bottom of the motorhome. Pulling out the carpet and checking the floors, but wasnt sure about the furnace vents
I've never been able to trust guest in an RV if they are not really familiar with them. Don't know the age of your SIL, but no excuse for leaving water running. Good luck.