Originally Posted by PaloAltoMark
I went back and reviewed my notes and think I found the answer.... I fly sparged but the water temp was probably lower than 170 -- maybe 150 or 155 degrees. Let me know if you think that would be the cause of the problem.
Here are the basic fact:
Grain bill was about 13 pounds - mostly 2-row malt. The recipe also called for 1 pound of corn sugar to be added to the wort after mashing and sparging.
I added 170 degree water to the grain to do the mashing. This made the mash a little hot (165 degrees) for the first 15 minutes but it cooled to about 155 for the rest of the 1 hour process.
When I sparged, I think I used water that was about 150 or 155. I did this as a fly sparge which took about 40 minutes and yielded about 6 gallons of wort.
I took the specific gravity reading of the wort + the sugar which was 1.056. On six gallons of wort, I calculated the total gravity as 336. So to achieve the target gravity of 1.074, I needed to boil the wort to a calculated 4.5 gallons. I did this but the actual yield turned out to be a little over 4 gallons at 1.074.
The low sparge temp might not have rinsed the grains well.
Did you stir the wort before taking the reading? I am a fly sparger, if that is even a correct term, and the last running are thin with the thickest wort on the bottom. Actually, last week I made a batch and took a reading, 1.020, What!!!, I stirred my boil kettle and walla, 1.070.
Here is what I do to make sure my grains are rinsed well. Take what you want and leave the rest.
After mashing in at whatever temp and duration for the style, I stir the grain up real well and remove a decoction and boil it for 20 minutes. I add half of the mixture back in and take the temp. I continue to add some until the temp is 168. I will add the rest once it cools. Now I use my sparge water, 170, and start my sparge arm. I clear my runnings and start the sparge. I turn the sparge arm on and off to keep the water a couple inches above the mash. Also, I stir the top of the grain bed by pushing the grain out towards the sides of the cooler, only about 3 inches down, to ensure that the sparge water is running thru the grain, not around the on the sides of the cooler. I average 90% efficiency. However, I attribute this to a good crush on the grain as well.