Efficiency reading confuses me

[edin88]

I did an all grain batch of a big oatmeal stout and while I was collecting wort I took a hydrometer reading after I had about a gallon or 2 of wort in my kettle. The reading was 1.072 and the temp of the wort was 140 deg. F (which corrects to 1.092 i think). I took ANOTHER reading of the same wort right as I finished collecting my 7 gallons in the kettle and this time it was predictably a LOT lower, something like 1.012.

My post boil OG at 60 deg. F was 1.072

I feel like something went wrong somewhere? Did I collect too much wort? After the boil I had like 6 gallons, maybe just a bit more, so I boiled off a gallon. I just feel like the OG should have been higher. I keep getting crap efficiency and I can't understand why. I don't think it's the crush cause I've bought grains from 4 different stores and i always get around 63% efficiency.

but the original question is more about if my hydrometer readings make sense or if i messed that up somewhere. I tested it in some 60 deg. water after the brew day and it read 1.000 so I guess it's right?

 

[stpug]

You would need to provide your recipe/grainbill as well as your volumes to begin breaking it down.

However, a 1.072 stout is pretty decent granted it's not an imperial stout but you never said that's what you were making. First running gravities are hard to judge because everyones process differs, plus you had the temperature correction factor going as well. Preboil gravities are your first sign of things to come (i.e. how efficient you were at converting and extracting the sugars) and this is a good place to make adjustments to your batch if needed BUT you need to know your absolute volume as well.

Collecting too much preboil wort means you will need to boil longer to reach your intended batch size but should not account for inefficiencies; in fact, collecting more wort than needed should help your efficiency but probably only a point or so.

Was your post boil 1.072 gravity before or after you say you boiled off a gallon? If it was before, then what was your final gravity and volume into the fermenter?

My friend keeps getting crap efficiencies (50s), yours are just lower than you'd like to see but consistency can make up for it. As long as you are consistently getting lower than you'd like then you can adjust your grainbill and for a couple more dollars you'll be hitting your gravities consistently.

Again, your recipe, volumes, and gravities would all be needed to assess your overall brewhouse efficiency.

 

[duboman]

IMVHO, your adjusted pre boil reading at 142F is a waste and inaccurate.

Any reading taken over 100F has the ability of being wrong even when adjusted for temp.