Parti-Gyle Brewing & Estimating OG

Randy Mosier has a scale that's worked with my system. There are also a few online calculators.

 

It's been a while since I've done partigyle (and I usually did the 33/66 split rather than the 50/50 split) so my thinking might be off / rusty, but I think one way to look at it using the beersmith numbers is as follows:

If your normal mash extraction (non-partigyle) is 78%, then on a partigyle you should extract 58% of that 78% on the first runnings and 42% of that 78% on your second runnings.

first runnings = 0.78 x 0.58 = 45% of the total extract
second runnings = 0.78 x 0.42 = 33% of the total extract

 

Here is the Mosher table...

http://morebeer.com/brewingtechniques/library/backissues/issue2.2/moshertable.html

It seems to suggest that on a 50/50 split, your first runnings will be double the strength of your second runnings. So that means you would get 66% of the total sugars you extract in your 1st runnings and 33% of the total sugars you extract in your 2nd runnings. I still think the more beer estimate of 58% in the first and 42% in the second is closer to what I've experienced though.

So your math, using the mosher estimate, would be:

Total points available - 100
First runnings - 66% * 100 = 1.066 OG
Second runnings - 33% * 100 = 1.033 OG

So your math, using the beersmith estimate, would be:

Total points available - 100
First runnings - 58% * 100 = 1.058 OG
Second runnings - 42% * 100 = 1.042 OG

Another way to think about the beersmith claim is as follows:

58% of the extractable sugar in the first runnings
42% of the extractable sugar in the second runnings

so the first runnings get 16% more of the total extract

beersmith says a 1.060 beer would be split to a 1.070 and a 1.050
1.060 + 16% = 1.070 (60 x 1.16 = 70) and 1.060 - 16% = 1.050 (60 x 0.84 = 50)

 

Sorry my 2 previous replies should have been worded a little more clearly:

I was saying, assuming your normal mash extract = 78% of the POTENTIAL extract in a grain bill
first runnings = 0.78 x 0.58 = 45% of the POTENTIAL extract
second runnings = 0.78 x 0.42 = 33% of the POTENTIAL extract

beersmith is saying
58% of the ACTUAL EXTRACT in the first runnings
42% of the ACTUAL EXTRACT in the second runnings

mosher is saying
66% of the ACTUAL EXTRACT in the first runnings
33% of the ACTUAL EXTRACT in the second runnings

I think I got that clarification right and hope it helps!

 

The difference btw your mash efficiency and your brewhouse efficiency is the sugar lost btw the boil kettle and the fermenter. So its the sugar left behind in the wort in your kettle dead space / wort mixed with trub you opt not to transfer + the wort you leave in your transfer lines / chiller (if any). So, for example, say your mash efficiency is usually 78% and your brewhouse efficiency is usually 74%... you are losing 4% of the sugars btw the trub / dead space wort you leave behind in the kettle and the wort you choose to leave behind in your transfer hoses and chiller.

I assume you will be partigyling by collecting your 1st runnings in one vessel and your 2nd runnings in another vessel. Then boiling them at the same time in those two vessels. Then chilling and transferring the 1st one that is done to its fermenter. Then chilling and transferring the last one done to its fermenter with the same transfer hose through the same chiller. Is that correct?

If so, your brewhouse extraction will just be a little lower than usual (the amount of wort in the 2nd kettles deadspace / mixed with trub) seeing as how you will probably not flush the wort in your transfer lines and chiller from your 1st batch down the drain. Instead you will probably push it into your 2nd batch fermenter when you pass your 2nd batch through the chiller and transfer it to its fermenter. If this is what you do, I'd expect your brewhouse to be around 72-73% instead of 74%.

If you opt to dump the wort left in your transfer line and chiller down the drain after transferring your first batch, then doing the same with your second batch, the usual difference between your mash efficiency and your brewhouse efficiency could potentially double. So you'd end up with 70% brewhouse rather than 74% brewhouse.

NOTE: If for some reason you are trying to figure this out so that you can load this batch into brewing software, I recommend that you enter it as 2 separate batches. Put the same grain bill in each batch, but adjust your mash extraction and brewhouse efficiency accordingly for each entry. This will also allow you to enter any differences in hop additions, yeast pitched, etc between the two brews.

 

I also recommend you consider "capping" your second runnings beer.

You make the cap by doing the following:
take 1# of speciality malt & soak it in room temperature water for 24 hours (I mill mine first but you probably don't have to)
run the mixture through a strainer or cheesecloth to separate the grain from the liquid.
Add the liquid to the 2nd runnings beer boil kettle either at the beginning of the boil or in the last 15 minutes
By "capping" the second runnings beer, you will add additional flavor, color, and a small amount of extract to it

 

Not sure if it had to do with my crush...but my first parti-gyle brew was a 50/50 split and iirc it came out as 1.090 or so from first drain and 1.032 from second drain. OG with a 78% brewhouse efficiency was 1.061 for the total 11 gal. batch. Obviously nothing close to the 58%:42%, more like a 75%:25% split. My only thought was it had to do with my crush because everything went smoothly on brewday...