By chance, is your expansion tank overflowing thru the clear hose (yellow circle) onto the ground when it runs and heats up? I know it would seem like a question that doesn't need to be asked but... I thought I would throw it out there.
If your lower hose had become brittle and cracked (arrow) I would think that you would feel or see evidence of the fluid staining around the top of the A/H unit or along the left side down near the carpeted floor.
I'm not sure if the Anthem A/H is situated similar to ours in the bay though.
John & Maria - Chester (furry kid)
2017 Cornerstone 45B - FMCA-#489135
2012 Scion XB - Pushing hard