Doing a batch of Innkeeper this weekend (all-grain) and running the numbers.
Kit comes with 6.25 lbs. of grain. At a mash thickness of 1.3 qts./lb. that gives me roughly 2 gallons water needed for the mash. But then that also leaves me with 5 – 5.5 gallons for a sparge?
I usually try to do even runnings but this one is going to be tricky unless I go 2.5 qts./lb. (giving me 4 gal. mash and 3.5 gal sparge).
Any problem with doing that? Any other suggestions?
Bump up your water to grist ratio to 1.5 to 1.75 qts/ lb. don’t forget that you will lose volume due to grain absorption. I often do a mashout of 1 gallon too which should help.
Not sure I understand what pre-boil volume you’re shooting for. I assume you’re batch sparging?
This is how I work it out based on information from dennybrew.com
Batch size - 5.25gal
Boil off - 1.5 gal/hr (my rate)
Preboil - 6.75
Loss to grain .6gal (.1gal/lb grain)
tun dead space loss - ~.5gal (my tun, yours may be different)
Total water needed 7.85gal
4.5 gallons strike water would yield you approximately 3.4 gals first runnings.
Batch sparge with 3.35 gals should get your pre-boil volume.
Look at dennybrew.com. He explains it a lot better than me.
Why are you worried about a ratio of 2.5:1? When I brew session beers, I use a thin mash with excellent results. I’ve got one on tap now for which used that exact ratio and I’ve had people asking for my recipe. 
