I've setup my initial conditions with temperature of 160 degrees F and one of my boundary condition with 160 degrees F but around the 12th iteration the temperature drops to 80 degrees.  Its not a gradual decrease from 160 to 80 degrees, one iteration is at 160 then the next iteration its at 80 degrees F.  I cant tell if its affecting my fluid properties, assuming it is.  What am I missing?