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Decided to brew a Guinness clone using an all-grain method! This is our second attempt at an all-grain brew, and we bought a larger pot for the mash, and I rigged up some insulation and thermal mass to help keep the temperature stable during the mash.
link to pdf of above in case that link breaks
Bought all ingredients from Northern Brewer:
Wyeast 1084 Irish Ale Yeast2.4 oz. East Kent Goldings (EKG) Hop Pellets2.5 lbs. Flaked Barley
Prepare the grain
Day before the brew, I used a kitchen aid grain attachment to crack the brewers malt and the black patent malt (video here). Next day I mixed in the flaked barley with these.
Mash
Mash setup: wrapped and tied a towel around a 42 quart aluminum pot - towel is to provide some insulation to maybe make it easier to maintain stable 150 F temperature during mash. Put that on the an upside down cast-iron pan over the smaller front burner on the stove. The pan serves two purposes: (1) provide more thermal stability in the heat source - in theory can turn off the gas and the cast iron will continue to transfer heat to the pot above (2) keep the flame away from the towel by providing spacing. NB: had to pull the oven out from the wall a few inches otherwise this combination would not fit under the microwave (thanks to my better half for this idea!).
Measured out the water for mash via weight because I didn't have a gallon jug handy - needed 2.66 gallons, so:
2.66 gal *8.34 pounds/gal * 2.20462 kg/pounds = 10.06 kg of water
(Of course I didn't need to do this calculation b/c the recipe also stated it was 10 liters of water, 1 kg water == 1 L of water!)
Used the Kitchen Aid bowl to measure the water and a scale, made it very easy:
Added the water to the mash setup, started heating - picture below. The bottom edge of the towel started to get hot, so I folded it up so it was further away from the flame, then it was fine.
When it reached ~160 F, added the grains, stirred them in, checked the temperature - 150 F:
You can also see in this picture the thermometer suspended in the mash, it is tied to the handle to keep it in place, this made it easy to check the temperature. I started with the heat at the lowest setting and I made temperature measurements every made 5 minutes, I recorded these and some adjustment to the heat in Appendix A. Important note - the temperature appeared very stable until the end, when we started cooking some eggs in a small frying pan adjacent to the mash. Seemed to be that was enough extra heat in the vicinity to raise the temperature by 4 F. Based on past experience, expect if we had used the oven or boiled water it would have had a similar or stronger effect.
Yeast
Pulled the yeast out of the fridge, following the package instructions, smacked the package to break the internal structure containing the yeast nutrients. This was at 10:34 AM, about ~6.5 hours before the yeast was pitched into the carboy.
Collect & Sparge
After the mash completed (60 minutes), I started boiling water so that I could add enough to raise the temperature to 170 F. I should have add the water boiling already, this did not quite work out. Appendix B has my attempted calculation of how much water it might take using some aggressive assumptions. I ended up adding 3.4 L of boiling water but it only made the temperature 154 F for a variety of reasons, not least b/c the mash cooled off while I was boiling the water and I didn't include the heat capacity of the grains in my calculation.
I used a strainer to scoop out the grain, then when that stopped being effective, I poured the mixture through a strainer into my wort pot. Then I rinsed the grain with 170 F water - about 3 L.
Boiling the wort
Started the wort boiling, took awhile to come to a boil partly because I kept the lid off because there was a lot of foam on top and I was sure it would boil over if lidded and unwatched. Once it was boiling I turned the heat down a bit and put the lid on most of the way, but with a crack showing to allow me to check and prevent boiling over. After 30 minutes of boiling, added the hops, boiled for another 60 minutes.
Finishing up
The lid of the wort pot was covered in some solid material, and similar material covered the top ~2 inches of the pot. From taste it seemed to be spent grain and have a hint of hops. Rinsed of the lid so that the material wouldn't fall into the wort, and was careful to not disturb the top ring of material.
To cool the wort, put the pot in a bathtub filled with cold water, then switched and put it in a large cooler that the pot just barely fit in. After the water in the cooler had heated up to ~65 F, I emptied it (it had a drain plug luckily) and refilled. After two of these cycles the wort was 80 F, so then we attempted to siphon it into into the sterilized carboy. I tried to get a current going to capture debris in the middle / vortex, but it didn't work, and the mixture was so thick that siphoning didn't work, so I used the auto-siphon to just pump the liquid into the carboy.
There was probably ~3 gallons of liquid in the carboy, added water to fill it to the top (of the straight / cylindrical section, allowing plenty of head space). Pitched the yeast, added the airlock - a tube from the top of the carboy into a pitcher of water. Now we play the waiting game.
Extra thoughts
Also noticed that ~2-3 g of water coats the sides of this bowl
Appendix A - heating measurements
Temperature measurements while heating water for the mash (min, F)
10 86
15 102
20 116
25 128
30 142
35 152
turned heat down from 7 (max) to 3
39.6 158
turned heat down to 2
Temperature measurements while maintaining mash (min, F)
heat at 1 (lowest)
0 148
5 151
turned off heat
15 149
turned on to 1
20 150
25 150
30 150
35 151
40 146
turned up to 2
45 154
50 155
Appendix B: calculation of amount of boiling water needed to add to mash to raise temperature to 168 F
Mash is / starting at: 10 L at 153 F (340.4 K)
Want to add X liters of water at 373 K
To get to to T total liters of water at 168 F (348.7 K)
Heat content of the mash by itself plus the heat content of the boiling water by itself should equal the heat content of the combined mixture at 168 F / 348.7 K. Use that equation to calculate amount of water.
(heat content of mash) + (heat content of boiling water) = (heat content of final mixture at 168 F / 348.7 K)
heat content = Cp * T(K) * mass
Assume Cp is equal for all, assume density of water for all therefore mass == volume (kg == L)
heat content of mash ~= 10*340.4 = 3404
heat content of boiling water ~= x * 373
heat content of final mixture ~= (10 + x) * 348.7 = 3487 + 348.7*x
Putting it all together:
3404 + x*373 = 3487 + 348.7*x
24.3 * x = 83
x = 3.4 L
Didn't work quite work! Final temperature was 154 - potential reasons why the calculation failed:
- did not account for the mass / heat capacity of the grains
- mash had cooled off some by the time the water boiled and I added it to the mash
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