Hey All!  For two seasons in a row now when "summerizing" my trailer, I've discovered that the plastic fitting for the hot water line behind the shower (the white 90 degree angle fitting in the closet) has cracked (from freezing temps) necessitating a quick repair.  Both seasons I "winterized" the trailer being painstakingly careful following Scamp's instructions; i.e., draining everything including the hot water heater and all the fixtures and lines, adding RV antifreeze and running it through everything, etc.  Obviously, I'm doing something wrong since this same fitting has cracked two seasons running.  Would it be better to blow air through the system when winterizing, or does anyone else have ideas?

Thanks everyone for your input!