I want to follow up on this sparge temp issue. Clearly the previous posters who said that tannin extraction is due to pH are correct. But I would argue that it is also a function of temperature. According to a number of brewing experts (Palmer, et al.) one should not sparge with water over 170* specifically to avoid tannin extraction.
Now I am fairly sure that the experienced brewer who monitors the mash pH, can and does (as you have said you do) avoid tannin extraction above that temp. What I am saying is that this practice should probably be left to those experienced brewers who know for sure it will work - but not for the new brewer nor should it be communicated that this is a general rule.
For the average home brewer the extremely small cost associated with the increase in efficiency is basically of no value, but the safety in being sure to avoid tannin extraction would be far more important IMO.
I hesitated in saying the above for a couple of days because I am not what I would call an expert home brewer, and as a consequence usually defer to those with more knowledge and experience... But I think I'm right on this point. However, as always I am open to being corrected.
Steve, you can look at it this way...if your pH is good, you can sparge with water much hotter than 170 with no ill effects. After all, if it was temp alone, decoction mashes wouldn't be done.But if your pH is off, it won't matter much what temp water you sparge with...you'll still risk tannins.
Since I don't have any way to check pH I try and keep my sparge temps. under 170f just to be on the safe side. But your saying it doesn't make a differance?
I know this is off the original topic but these these responses really sparked my interest...assuming we control the pH of the mash, and we're only sparging, why heat up sparge water at all? I've always heard we should have sparge water around 170 but never above that temp for all the reasons listed in previous responses...but if the core of this thread is saying water temp doesn't matter for tannin issues why bother with heating sparge water?