Sparge Water temp question....

I am having trouble with efficiency and was wondering if perhaps my sparge process is to blame...

I do a batch sparge (70 quart cooler - 11 gallon batches post-boil), and my volumes and stirring are probably ok. However, I am wondering if my sparge temp is too low. For 27 pounds of grain, mashed at 152 degrees, what should a sparge water temp be? I used 8.5 gallons on my last batch that had 27 pounds grain mashed at 152 degrees for 75 minutes. OG was way off post-boil. Sparge water temp was 174 degrees.

I can only think that sparge temp was to blame. I crush my own grains at the LHBS and have never had a problem before.

Thanks ahead of time for any feedback.

When I double batch sparge I usually need the first sparge water addition to be 185 to 190F to get the grain bed to 170F. The second sparge water addition only needs to be about 180F to maintain the 170F bed temp.

Of course it depends on your MLT, amount of grain, temp. of grain bed before addition etc. etc.

Efficiency is affected by many more things than sparge water...That's a big can of worms there & much info can be found searching the forum.