Long Time Fly Sparger, First Time Batch

Hit 70% efficiency on an AG , 10 gallon, 28lbs grain bill recipe. I think the best part of batch sparging is the peace of mind--there isn't any invisible channeling to worry about, it just works.

I'm wondering though, instead of two drainings, why not three?

You can sparge as many times as you'd like as long as you keep the gravity of the runnings in the 1.012-1.010 range. Below that you will begin to extract tannins. There is also an argument to be made about the quality of the wort. IMO most only double sparge because of the additional time further sparging can take. Personally, I double sparge, even with 10 gallon batches (unless it is 10 gallon of a huge beer, which I haven't attempted yet, and don't know if I want 10 gallons of a huge beer ) Having said that, I get ~79-80% brewhouse efficiency, so I'm happy.

YMMV

http://braukaiser.com/wiki/index.php/Batch_Sparging_Analysis
Three can increase efficiency a few points. I get around 85% with just two.

Awesome Conroe, so basically on average the difference in 20lbs grain bills in efficiency between 2 and 3 runnings is ~1.5%-2%. Basically not worth doing, unless you are in an efficiency competition

So this question has been troubling me for some time now. I'm making the jump to Partial Mash on my next batch to give me a feel for the process before going AG. I have been using Beersmith to tweak my recipe calcs for the PM and have done a ton of research on HBT and concluded that I would do 3 runnings. I know that the efficiency won't increase significantly by doing three runnings, but my primary motivation was to extract more wort from the grist so that I wouldn't have to use more water in my keggle to come up with my pre-boil volume. With my current grain bill, I'm calculating ~4.5gallons of wort (after grain absorption) and I will add 3 more gallons to pre-boil (major evap rate on my system). I also read somewhere on the forum that a rule of thumb is to stay within 4 qts per pound of grain when sparging and that these volumes can pretty much be divided up aas necessary. Not sure if I misinterpreted the thread when I read it but either way here are my questions:

1. How much sparge water should I use if I only do 2 runnings?
2. If I use too much sparge water, won't that make my mash thin and consequently impact my beer profile?
3. Can someone review my brew recipe below and advise how the mash profile should be tweaked?

Brew Type: Partial Mash
Style: Oatmeal Stout
Batch Size: 5.50 gal
Boil Volume: 7.50 gal Boil Time: 60 min
Brewhouse Efficiency: 75.00 %

Ingredients Amount Item Type % or IBU
3 lbs 4.7 oz Extra Light Dry Extract (3.0 SRM) Dry Extract 36.18 %
3 lbs Pale Malt (2 Row) US (2.0 SRM) Grain 32.97 %
16.0 oz Roasted Barley (300.0 SRM) Grain 10.99 %
12.0 oz Caramel/Crystal Malt -120L (120.0 SRM) Grain 8.24 %
12.0 oz Oats, Flaked (1.0 SRM) Grain 8.22 %
5.0 oz Chocolate Malt (450.0 SRM) Grain 3.41 %
1.00 oz Fuggles [4.00 %] (60 min) Hops 13.8 IBU
1.00 oz Goldings, East Kent [4.50 %] (60 min) Hops 15.5 IBU
0.11 oz Pearle [7.80 %] (60 min) Hops 3.0 IBU
1 Pkgs Irish Ale (White Labs #WLP004) [Starter 1500 ml] Yeast-Ale

Estimated Original Gravity: 1.053 SG (1.048-1.065 SG)
Estimated Final Gravity: 1.015 SG (1.010-1.018 SG)
Estimated Color: 35.0 SRM (22.0-40.0 SRM) Color [Color]
Bitterness: 32.3 IBU (25.0-40.0 IBU) Alpha Acid Units: 9.4 AAU
Estimated Alcohol by Volume: 5.01 % (4.20-5.90 %)

Mash Profile Name: Single Infusion, Medium Body, Batch Sparge Mash Tun Weight: 0.00 lb
Mash Grain Weight: 5.81 lb Mash PH: 5.4 PH
Grain Temperature: 70.0 F Sparge Temperature: 168.0 F
Sparge Water: 3.07 gal Adjust Temp for Equipment: FALSE

Name Description Step Temp Step Time
Mash In Add 8.00 qt of water at 165.1 F 154.0 F 60 min
Mash Out Add 6.50 qt of water at 192.3 F 170.0 F 10 min
Mash Out Add 6.00 qt of water at 170.0 F 170.0 F 0 min

Mash Notes
Simple single infusion mash for use with most modern well modified grains (about 95% of the time).

#1: I haven't used Beersmith in a long time, but it has gotta tell you how much. The total amount of water is a) what you want out, plus b) what the grain will absorb, and c) how much 'lost wort' your system has. I usually plan somewhere in the neighborhood of 1/2 a quart lost per pound, and my new mash tun loses at least a quarter, perhaps two. But basically from what you wrote I think you'll be fine.

#2: Yes But don't sweat it, just make sure you have say half a pound of LME/DME extra just in case, and take lots of notes. The LME/DME is to correct any issues, the notes are to make sure there aren't issues in the future.

#3: To my eye your mash looks fine, the only thing that kinda puzzles me are the Kent and Fuggles at 90 minutes. Not that it isn't fine, I just like the taste and aroma of those guys so I never use them for bittering. Many English breweries say they use them for everything, bittering and aroma, but according the Graham Wheeler if that was true then English brewers would be using 5x the amount of Fuggles and Kent Goldings actually produced

Ya look good. Take notes, don't boil over, and have fun.