What model Precisiontemp? If you have the TwinTemp combined LP & electric unit, it is a hydronic system with both LP gas burner and 120v electric heat element. Hydronic systems don't have hot water storage tanks - they are a demand system where water is heated in a coil as needed. There seems to be no reason for an anode and I don't see any reference to one. There is, however, a boiler that uses an antifreeze-type boiler fluid. All this is covered in the Installation & Operation Manual.
Former owner of 2004 American Tradition and several other RVs
Home is in the Ocala Nat'l Forest near Ocala, FL
Summers in Black Mountain, NC