jrskjei: thanks, a reasonable argument presented in a civil manner. Glad you're here.
But I do disagree with a few of its points.
Using the example above, if you collect 7 gallons but at a lower gravity of 1.030 the total sugar extraction would only be 210 points instead of 216.
I assume you mean from the same mash, i.e., run off 7 gallons instead of 6.
Question: If you take your example of 6 gallons with 216 points, and add a gallon of pure water to it, you would have 7 gallons of 1.0308 wort...still 216 points. How then can you take the same 6 gallon 216 point wort, add a gallon of water to it by running that water through the lauter tun, and somehow lower the total points to 210?
I'll agree that there may be limited gain from running additional water through the lauter tun, maybe even zero sugars, but no way it'll "subtract" from what you already have, and lower the points you've already extracted.
I like the page Kai has created on the subject.
His findings, for both batch and fly sparging, support the contention that "The more water that is available for sparging, the more extract can be rinsed from the grain." http://braukaiser.com/wiki/index.php/Understanding_Efficiency
Ah, you guys are just arguing two different things and being stubborn about it.
What we have here is .....
Mash efficiency(into the boiler) VS Brewhouse efficiency(into the fermenter)
But by all means carry on - I am enjoying this.
A very good point beerocd.
I have assumed that mash efficiency -- pre-boil -- was the type in question...but I may be wrong!