JuanMoore
Getting the banned back together
mgortel,
You may find that the amount of water needed to hit mash out really cuts into your sparge water. This is the main reason many skip it. You can do a decoction for mash out, or direct heat your mash (if you mash in a kettle) to avoid an infusion. But with a large grain bill, a mash out infusion is going to leave you with precious little water to sparge with.
I don't think you can necessarily calculate it so that you add boiling water for a mash out, and then have your first run off be 1/2 the preboil volume. That would be a special case with a very low gravity beer (ie small grain bill).
+1 to this. When I did mash-out I always used boiling water to minimize the volume.