The Disappearing Efficiency Dilemma

I just brewed my third all-grain batch last Friday and I have some serious questions about efficiency! The recipe is as follows:

11lbs – 2-row
0.5lb – Crystal 20
0.5lb – Crystal 60
1lb – Carapils(dextrin)
1oz – Centennial (8.7AA) @ 60 mins
1oz – Centennial (8.7AA) @ 15 mins
1oz – Centennial (8.7AA) @ 5 mins
1oz – Centennial (8.7AA) @ 0 mins
1oz – Centennial (8.7AA) @ dry hop

Mashed in my 5 gal. cylindrical Rubbermaid @ 150 for 60 mins, stirred approx. every 10 mins.
Because of my limited equipment and kitchen space my standard operating procedure is to collect the

1st runnings (and most of the 2nd) in my 4 gal stock pot, the 2nd and 3rd in two 1.5 gal stock pots, and the 4th in a saucepan.
Gravity results of runnings:
1st = 2 gal @ 1.073
2nd = 2.5 gal @ 1.053
3rd = 2.5 gal @ 1.026
4th = 0.5 gal @ 1.018

Using BeerSmith dilution tool gave me a combined pre-boil gravity of 1.047 for the 7.5 gals of wort, which Brewers Friend calculates to be an efficiency of 74.29%. After a 60 min boil I was left with just a little over 5 gals, which I was expecting to come out around 1.065 - 1.070. I know what I should have done was to take a bunch of post-boil gravity readings and use the dilution tool again, but I forgot so I took a reading after it was all cooled to 60 degrees and poured into the carboy and came up with 1.052. Is this even possible? Could it be that maybe I just didn’t mix the various worts well enough before taking a reading and that I’m not stuck with 5oz of hops in a 1.052 ale??

Its possible. I did a mead a couple months ago and when I went to take my gravity readings the first was sticking the thief all the way to the bottom after I mixed the must and the reading was impossibly high, so I took one from around the middle and it was lower then I stirred it and my third reading was about what I was expecting. Now that was a mead so there was no question of efficiency involved. I can't say for sure that that's what's happening in your case. Maybe you could try to take another reading today and see where you're at. Obviously fermentation has probably already started but maybe the gravity levels in the solution have evened out and it might help you figure out where you started at. In the future though you ought to just stir the heck out of it since aeration is good at that point then there won't be any question about the efficiency.

First thing, you've really only got 3 oz. of a medium AA hop in your boil, leading to ~ 51 IBUs @ 75% eff, so even if that OG number is good, you're still @ ~1:1 BU:GU, not a bitter bomb. My sense is that your fementer reading sat a bit & resulted in some wort stratification, the heavier sugars settling a bit. It's my inkling that if your starting gravity reading of 1.047 is true, you cannot boil off over 2 gl & raise the gravity by only .007. I typically get between +.010 & .013, boiling off 1.9 gl in an hour.

-d

Having 4 different readings pre-boil gives a lot of room for error. Also, you sampled using two different methods (1st in many different pots and 2nd in one large container), also giving room for error. My guess is that your measurements are wrong somewhere along the way. I agree with the posts above, I think you're closer than what you measured it to be.

Also, I would highly suggest getting a larger boil kettle. If you're like me and can't afford one of the really nice SS boil kettles, use a turkey fryer and aluminum kettle. My 9 gallon kettle cost me around $40 including the propane burner and stand. I haven't had any issues or off flavors at all.

Well, I did pour the largest pot with the heaviest wort in it first and then topped off with the other smaller ones. My normal routine is to shake the carboy for at least 5 mins to get a decent amount of aeration but on Friday I was in a hurry, I had to get ready for deer hunting! I would take another gravity reading now except that there's a good 4 inches of krausen on top of the wort at this time and I'd rather not mess with it.

A larger boil kettle is definitely the next major brewing purchase I'm going to make. Hopefully SWMBO will let me treat myself to the 15 gal stainless with valve & thermometer:

http://www.amazon.com/dp/B003EWLTHY/?tag=skimlinks_replacement-20

But if times are tight in December I might just go with the turkey fryer idea and then upgrade later. The hardest part of making the transition from extract/PM to all-grain has been the financial barrier, to get a full boil I need a larger pot, to cool a full boil I need an immersion chiller, plus I need a kitchen scale, & grain mill, etc... So many needs + so little money = one sad brewer!