[EHall]

I've done that a couple of times... I just throw about 1/2gal of water in a smaller pan and boil it, I can usually boil it in less than 15min... then pour a bit at a time in the MT stir and take a temp until I get it where I want it... I'm not sure about the time threshold, but I'd have to guess anything less than a 1/2hr isn't going to harm anything...

[timmyr]

Have you read Kiaser's site?
http://braukaiser.com/wiki/index.php/Understanding_Efficiency

+1  I typically hit about 80% and was trying to lower it in effort to ensure no issues with over-sparging.  Then I figured, hey, as long as I am consistent, I'll leave it alone.  I batch sparge and take lots of notes.  I'd say if you hit 70% all the time...you are good to go.  Brewing Classic Styles basis all their recipes on 70%. 

[bschwoer]

IME, it's just not that big a deal to hit an exact temp.  I almost never hit what would be called a "mashout" temp.  I simply use sparge water in the 185-190 range (every time, no changes) to increase the temp of my grain to whatever before I run off the sparge.  This encourages conversion to complete.

Be careful with your water temperatures during sparging.  You do want a higher water temp because it helps the wort flow better (lowers viscosity making the fluid flow easier).  However, when you exceed 170 F you will begin to draw the tannin's (comes from grain husk) out of the grain and this leads to an off taste.  Several accredited sources recommend not exceeding 168 F to prevent the removal of tannin flavors from the grain.

During your mash, the ideal final temp is typically between 150-160 (depending on your grains).  These temps are what promote "conversion to complete" as they are what promote certain enzymatic activity that breaks the larger starch chains into smaller chain sugars for the yeast to process.  Going above these temps just promotes a lower viscosity for flow and washing.

I recommend "Brew Chem 101: The Basics of Homebrewing Chemistry" for some good information on basic chemistry that will provide guidance on pH (as another post mentioned) as well as the importance of temperature among other tidbits.

[gordonstrong]

Be careful with your water temperatures during sparging.  You do want a higher water temp because it helps the wort flow better (lowers viscosity making the fluid flow easier).  However, when you exceed 170 F you will begin to draw the tannin's (comes from grain husk) out of the grain and this leads to an off taste.  Several accredited sources recommend not exceeding 168 F to prevent the removal of tannin flavors from the grain.

You need temps above 170F AND pH above 6 to extract tannins from grain. And those are the conditions that have to exist in contact with the grain, not measured someplace else.  If you don't monitor your pH, then keeping your sparge water capped at 168F is a good idea.  If you treat your sparge water so that it's less than 6, it doesn't matter what temperature you use (as far as tannins are concerned).

You boil (212F) decoctions without getting tannins.  Why?  Because your mash pH is probably around 5.3. 

[bluesman]

When considering increasing efficiency there are several things to consider.  Assuming the use of a fully modified malt one must take into consideration the crush and by that I mean exposing all of the starch within the grain while not destroying the integrity of the husk.  That can be done by milling your grain with a millgap setting between .035 and .040.

As others have already indicated keeping the mash pH (5.2 is ideal) in check is vital.  I use pH strips for checking the pH.  The type of grain and water chemistry will have an impact on pH.  There are some great books available that discuss this in great detail.

Mash tun and grain bed geometry will effect the run off.  I use a rectangular cooler and typically acheive between 75 and 80% efficiency.  Round coolers also work well.

Lautering.  Get the sugar out...all of it.  I use a Coleman Ultimate Extreme which has a recessed pocket below the tun floor which allows for all of the wort to drain from the tun.  Some say the color is also important...red vs. blue but the jury's still out on that one.  

[denny]

IME, it's just not that big a deal to hit an exact temp.  I almost never hit what would be called a "mashout" temp.  I simply use sparge water in the 185-190 range (every time, no changes) to increase the temp of my grain to whatever before I run off the sparge.  This encourages conversion to complete.

Be careful with your water temperatures during sparging.  You do want a higher water temp because it helps the wort flow better (lowers viscosity making the fluid flow easier).  However, when you exceed 170 F you will begin to draw the tannin's (comes from grain husk) out of the grain and this leads to an off taste.  Several accredited sources recommend not exceeding 168 F to prevent the removal of tannin flavors from the grain.

As Gordon pointed out, pH is at least as important, if not more so, than temp.  After all, you boil the grains in a decoction and no one talks about "tannin extraction" there!   Also, Kai Troester has done experiments with room temp sparge water and found no loss of efficiency or other detriments by doing that.  It seems there are many homebrew "rules" that have been repeated over and over that fall when they are subjected to testing and experimentation.

[kylekohlmorgen]

I wouldn't recommend trying to crush grains any finer... it usually doesnt get you a lot, and most times it just ends up in astringency/stuck sparges if you're not careful.

I just switched from a bazooka screen to a stainless braid (in a 10-gal Gott cooler) and went from 60% to 79% efficiency on the first brew with it (today). Maybe it was a fluke, but I'd like to think I did it on purpose...

...even though I didn't account for it in the recipe and now need to buy another package of yeast...

[Malticulous]

Get 85% consistently by breaking many of Denny's rules. I mash around 1.3qt per lb, mashout and double batch sparge. If I just single sparge with no mashout I expect closer to 80%. I have monitored pH and found a little calcium chloride is enough to keep it in cheak. I crush it with a barley crusher at the stock gap and use a Coleman extreme 52qt MLT.

Some will say that 85% is not good for the beer. I like my beer and it scores fine in competitions. Others will say the mashout infusion and splitting up the sparge is too much added work for the 3-5% gain. It's not very much more work. Granted, it only saves me about a dollar per batch. I brew enough that it adds up.

[denny]

Some will say that 85% is not good for the beer. I like my beer and it scores fine in competitions. Others will say the mashout infusion and splitting up the sparge is too much added work for the 3-5% gain. It's not very much more work. Granted, it only saves me about a dollar per batch. I brew enough that it adds up.

OTOH, I get an average 85% with a single sparge and usually no mashout.  Whatever works for you.  I brew about every other week, so at $26/year, saving a dollar per batch wouldn't make much difference to me.

[Malticulous]

I have no desire to change yor ways Denny, just saying your way is not the only way. 

[denny]

I have no desire to change yor ways Denny, just saying your way is not the only way. 

As I well know!  I encourage everyone to use whatever methods and techniques give them the results they want and the enjoyment they deserve!