What temp. are the mash runnings if you don't do a mash out for batch sparging? I would think they are < 168F during the time you batch sparge. Why is that not a concern?
Once I start recirculating I'll start losing heat, so < 150* for the first. If I add water at 168* I'll probably see somewhere in the 150s. ~194* sparge water on my system brings the grain bed to 168*.