Sam75 said:
Damn, I'd been wondering about this. So the actual sparge temp should be the temp of the water going onto your grain bed?
Having only done two AG batches thus far, this is one thing I still don't understand. I've read that sparging over 175F will release tannins, so I've kept my sparge temps down. My last batch, I heated my water to 185, hoping to bring the water in my HLT to 170. I think it went to 175, but upon measuring my temp on top of my grain bed, I was only getting maybe 160F, or so.
Perhaps a contributing factor to my low efficiency?
I've only done 2 myself so others can slap me upside the head if need be but... It would make sense that the higher temp you get the more free-flowing the runoff of the sugars which would lend to better efficiency. I'll trust them on the above 175 and the off flavors. My second batch yield was not as efficient as my 1st (1# more grain too) and I was scrambling once I recognized I was sparging with water probably a couple degrees cooler than the mash after it hit the mash. I'll try and creep up to 170 but I don't want to go over that. I might toss the sparge arm as well (return?) as that is a big variable on the temp management based on ambient temp. I like the thought of a gentle copper plumbing pour to reduce temp loss from the HLT. But I'm still just as concerned of the sparge PH and am going to hit this next time. Below is an excerpt from
http://www.beer-brewing.com/wort_separation.htm giving a summary of key points.
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Sparge Water
Water Quality
The quality of the beer may be affected if the sparging water is too alkaline. A pH greater than 7.0 is unacceptable; preferably, the pH should be around 6.0, which leads to better coagulation of proteins, better drainage of the grains, and a higher extract yield (17).
(DesertBrew: Mine is 8!)
Water Quantity
The total volume of sparge water will vary with beer styles and mashing processes. For both mashing and sparging, most designs assume a grist-to-water ratio of from 2.5 to 3.5:1, with 3:1 as the average.
Water Temperature
The temperature of the sparge water (7578ºC) must be higher than that of the mash to help maintain mash temperature and increase runoff. However, if the sparge water is too hot (above 80ºC), it will extract unwanted materials such as tannins, proteins, and unconverted starch (15).
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That and testing runoff gravity to determine when you should cease the sparge and it sounds like we'd be following a well defined and documented process.