Are you batch sparging? If so, you really don't need to do a mash. Mash out raises the temp of the grain to stop enzymatic activity that could continue over time while fly sparging. When batch sparging, run off takes so little time, there is not much concern with this. The only time I do a mash out is if I'm do a 12 gallon batch, and cannot heat all my strike water in my 7.5 gal kettle. And, when I have done a mash out, I typically heat the water to about 180* or so, and just mix it in. (carefully, remember HSA)