High gravities

[JMcG]

OK, help me out here, guys. I’ve had a couple of batches lately that were kind of wacky.
I try to brew by the numbers, and have been pretty consistent until recently. I use Beer Smith to plan the brew and figure temps for strike, step and mash out. Usually hit the numbers (within 1-2dF) and my OG’s and volumes are usually within tolerance.
The first time I had a big variance, I figured I made a mistake measuring the grain because my OG was way high (like 100% efficiency). Grain bill had called for 10# 12oz pale ale malt. No morning coffee yet - I thought , “I probably measured 12#.” But, it happened again this week, and I know I was careful with the measurements this time.
So I checked my readings and compared the refractometer against a hydrometer. No diff.
Checked my scale and changed the batteries. No diff.
I ran the numbers through an online calculator for brewhouse efficiency to double check. 101% eff. That can’t be right.
The only ingredient in common was Maris Otter. Two lager brews (with no MO) in between were spot on.
I don’t mind a bigger beer (1.080 vs. 1.070), but it makes planning brews difficult. Besides, recalculating hop utilization on the fly during the boil is aggravation I don’t need.
I think I must be missing something, probably obvious to more experienced brewers. Help me out?
jim

[Rob Martin]

That is really, really weird Jim, because our last 2, maybe 3 batches have been the exact same. I also thought, 'boy, I screwed up measuring that grain'. Our Schwarz was 10 pts too high, our Irish Red was 6-8 pts high. Also with us, we achieved a 99% efficiency when normally we are around 80%. My thoughts were, nobody gets 99%. It actually made our beer too high OG and I'm wondering what the IBU balance is going to be when it is done lagering.

Talking with Brick, he suggested we pre-heat our mash tun. During our initial strike, our temps came out too low, which caused our mash to be extended 30-60 min while we recirculated to bring the temp up. Otherwise, I don't have a clue.

[brick]

one other thing to check is that the grain information in your software is updated for new grain. This years malt has a little higher potenial extract. We have had to adjust all of our grain builds a little to keep things the same with the current malts.

[Frank]

I have read a few threads with this same problem in HBT. It seems that the common consensus is if a home brewer has greater then 90-93% efficiency one of three things are suspect. (In order from most to lease likely)

1. Volume measuring error either on the volume in side or volume out. Either a grain miss calculation or inaccurate measure of the final wort into the fermenter. I am always suspect of the markings on the side of the vessel. I prefer to weigh the wort in the fermenter then subtract the known weight of the vessel. To find the weight of a gallon of wort, multiply the specific gravity of the wort by 8.32lbs. Then take total wort weight and divide by the weight of 1 gallon to get a most accurate measure of volume into the fermenter.

2. Variations in grain yield. With any agricultural product there will be a variance because of a lot of inconstancies during the growth and processing of the final product.

3.Formula errors. If you do them by hand it could be a simple math error or if you have a program it could have an issue. Programmers are still human and they may have updated something and created an error somewhere else.

[JMcG]

10-12% higher I think. E-mailed Crisp with lot #. Couldn't find database on the net.
Guess if they don't answer I'll just change potential SG from 1.038 to 1.040.
Thanks, Brick!
Rob, it's good to know someone else noticed it, too.
jim