On all the yank sites (including howtobrew) they say not to sparge above about about 75.6C as you risk extracting tannins... so is that only for fly sparging then?
My understanding is that the idea is to not let your Grainbed get above that temp... your sparge water can be hotter, as long as it averages out to less than the 76.5 once its all mixed up... mind you, as long as your Ph is OK, even at a hotter temp it shouldn't be too much trouble... and most likely, if you are batch sparging, your ph WILL be ok.
From what you were saying earlier... I don't know if your mash and lauter has all that much to do with your problem... your extract efficiencies seem to be well and truly OK, you are just losing extract between the kettle and the fermentor.
I say, check that your kettle and your fermentor volume measurements are matching up a litres difference in 20 litres is 5% after all, make sure you take into account the 4% loss in volume measuring the hot vs cooled wort, how much are you losing to trub, chillers, spillage etc etc.
I find extract efficiency and pre-boil volumes easier to work with (I know that others dont, its just my preference) because then I don't have to factor in all the other stuff, and if they change, the only thing that changes is
how much beer I get, not
what beer I get.
A litre here or there in calibration or losses makes a big difference to the figures. 70% sounds OK and 60ish% not so great, but the difference in a 23litre batch is only a couple of litres
I only worry about efficiency so I can convert recipes from other people consistently, and to give me a clue whats going on if something suddenly changes in my brewing. I change nothing in my brewing practice, but get an unexplained drop in efficiency... then I know something else has changed and I can go looking for it.
If I'm getting anything above 70% (extract eff) then its plenty good enough from an efficiency perspective, and I focus completely on consistency and quality.
But thats just me
Oh and if you are the really really "must go for the gold" type efficiency seeker, you should be able to manage slightly better than 100% extract efficiency. Its only a figure derived from a lab standard mash after all, its eminently possible to get a better efficiency than the lab guys do and so you can be better than perfect.
Thirsty
