Last Runnings Constantly >5P

[derek.duf]

I've been really starting to work on improving efficiency on our 30bbl system (M/L, Kettle, WP). Been using sieves to work on the crush, which has definitely helped. The one problem I can't seem to solve is leaving sugars behind in the mash, our last runnings for an average 15P beer is always 5-6P. We've slowed down our sparge to right about 2 hours, but have not seen any improvement. If anyone could give any advice on what to improve in below process, I would really appreciate it.

Today's brew:

700# 2-row
550# Maris Otter
165# Munich Light
150# CaraPils
110# Melanoidan

Mashed at 150F with .32gal/#, mash pH = 5.4
Held for 50min, vorlauf for 10 min
Waiting to turn sparge water on until level drops to grain bed, sparging with 175F water until grain bed rises, lowering sparge water to ~170F
Sparge 32 barrels over 2 hours, preboil gravity = 1.055, efficiency is ~87%. Final runnings were 5P and 5.6pH

[Thirsty_Monk]

Last Runnings Constantly >5P

Your specs looks good. One thing is that thicker mash, more you sparge you get your volume. More you sparge, more sugars you rinse. At least in theory.

[dick murton]

I think the problem is simply that in order to get a gravity of 15P, you have to use more malt than expected simply because you need to cut the last runnings off early, otherwise your all up gravity in the kettle will be too low and you would have to boil to death. High gravity worts with simply mash tuns are not compatible with high extract efficiency. To me, this sounds about right, though I have not calculated anything out exactly - just used crude figures.

If you get far better extracts with say a 10 or 12 P wort, then I definitely would not worry - just accept that you cannot get all the extract out of HG brews.