AG #5 and #6 - Dr Jekyl and Mr Hyde - Brew Day

For some time I have been wanting to change my brew day process in order to maximise my volumes due to the fact that I have less time to brew. With that in mind I decided to brew a parti-gyle beer which would allow me to create two brews from the one mash. Parti-gyle involves using a grain heavy mash and producing one strong beer from the first running and then a weaker beer from the second runnings. I decided to forulate a recipe that would produce an IPA and an APA. The recipe I came up with I called Dr Jekyl and Mr Hyde.

One of the challenges with parti-gyle brewing is recipe formulation and gravity calculations and this is the one area where I fell down on this brew. I had estimated that I would be able to produce a beer of 1066 from the first runnings and then a beer of 1040 from the second runnings. The seconds runnings produced a beer of 1043 and so I was happy with that, however the first beer produced a monster of 1122! Obviously I had miscalculated along the way and so in the end I diluted this first beer down to a more manageable 1078.

Here are some pics of the brew day:

A total grain bill of 8.95KG was used, this was supplemented in the second runnings by the addition of 300g of DME. The grain used was Maris Otter, Munich, Crystal and Carapils.

One of the areas that I had struggled with in the past was to keep my mash temperature up, however having insultaed the mash tun much better I managed to only lose 1c over the course of the 60 minute mash. I mashed in at 68c and the temperature only dropped to 67 in the last 10 minutes.

This amount of grain was the most I ever used and certainly tested the max capacity of my mash tun. In fact I could not fit enough water in to give me the water to grain ratio I wanted and so I did a mini sparge of 5 litres to give me my target pre boil volume of 14.5 litres for the strong beer.

The first runnings appear very dark which is what you would expect from a 1122 wort.

No issues with the brew day as a whole (apart from the gravity miscalculation). Did two separate boils and the total brew day lasted 8 hours which was long, but at the end of it I had 20 litres of 1043 APA and 14 litres of a 1078 IPA. Fermenting both with US-05 and the next morning they were both fermenting happily.

Parti-gyle calculations:

Here is how I calculated my gravities, obviously it went drastically wrong somewhere and so if anybody can offer any advice that would be great. In order to get the total mash gravity I put all of the grain into beer tools and set it at a volume of 41.5 litres (14.5 for the big beer and 27 for the small beer). Beer Tools told me that this would give me a total batch gravity of 1044. If I split the batch into 1/3 - 2/3 then I estimated that I should get 1066 from the first third and 1040 from the second 2/3. Now obviously something went wrong as I ended up with 1122 from the first 1/3. Can anyone spot any obvious mistakes from what I did?