When I was at the Horn Rapids RV Park over the July 4th week the dripping was coming from that drip tube - from inside the tube or on the outside of the tube I didn't check. I did not see any dripping from anywhere else, but the coach was level. At home here I park the Coach on my driveway which is sloped downwards towards the street. The coach is backed into the driveway so the fore end is lower than the aft end. My air leveling will take out about half the slope, but it will not bring the front end quite high enough to make it level. Here in my driveway the leaking is coming from two places - the dripping appears to be coming from both front corners - left and right - of the Aqua Hot box. The dripping - remember, only when hot - is enough to leave two wet spots about one foot wide and five to seven feet long as gravity makes the dripped fluid flow downhill towards the street.
Replacing the tubing to the expansion tank is a good idea because this leak came on only in the past month that I am aware of, and it only leaks when hot and coming under pressure due to the heated fluid. Also, removing the radiator cap and checking that the seal is clean and smooth is another good idea. I think I will also pick up a 7 lb. radiator cap to see if that makes a difference in the amount of leaking. I am thinking if there is a split elsewhere in a tube or fitting, then the lower pressure should reduce the amount on leaking.
I am at the end of a roof maintenance project and just started a bathroom remodel in my house, so have been using the motorhome shower (the other house bathroom has a tub, no shower)... and there is no one around here that has the know-how to repair an Aqua Hot, as far as I know. So... I'm trying to get by with the coach's shower for a month or so.