After nearly three years of brewing (and two and a half years of all-grain brewing) 5 gallon batches, I decided to step it up a notch and brew my first 10 gallon batch of beer! That’s right, 1/3 of a barrel (well, almost [a barrel is actually 31 gallons]). Doesn’t sound like much or to difficult, right? Moving up to 10 gallons would require a little more planning than a normal brew day. Also, there was also a few questions I had to answer;
- Could my mash tun hold the grain bill?
- How would my boil-off rate be affected?
- Would it take a considerable amount of time to brew a double batch?
I started planning this day a few weeks ago with one of my regular brewing buddies. The first thing we did was decide “when and what are we going to brew?”. After throwing around different beers that we could brew, we finally decided a seasonal beer would appropriate. Now, we decided to brew the last weekend of October. So, being that it was very close to Halloween, we decided that a great way to celebrate would be to brew a nice, spicy, pumpkin beer. With the date and style set, what was next…
So, let’s get onto answering some of the questions…. Could my mash tun hold the recipe for a 10 gallon batch of Imperial Pumpkin Ale. Short answer, NO. Our grain bill was close to 32 pounds! Using my math, I figured that I can only hold 24 pounds of grain (with 1.25 qts of water/pound of grain). Now, we ‘could’ tone down the base malt and add some DME into the boil. Nah, why would we do that? We decided to use two 10 gallon mash tuns and split our grain bill equally between them. Basically, we purchased two, 5 gallon recipes to accomplish this. You’re probably asking yourself, “how the hell is he going to sparge two mash tuns?”. Yeah, this was not thought about until brew day. Well, we used the fly sparging technique and ran half the sparge water through one tun and half through the other. Our efficiency did not seem to be affected. If we go this route again, I will pick up some sort of splitter so we can run them both at the same time into the boil kettle.
Next question, boil-off rate… The boil off rate did not seem to be affected too much by brewing a double batch. We started with 12.5 gallons of wort and boiled it down to 10 gallons. Our boil time was increased a touch, but I normally boil off close to 1.5 gallons an hour with my current setup.
Finally, total brew time. Our brew day lasted around 8 hours. It was a long time, but I do not consider it excessively long. As a comparison, my normal brew day lasts between 5.5 – 6 hours. Remember, we did not sparge both mash tuns at the same time, we filled two mash tuns, and collected double my normal boil volume. I believe that the next time we do a 10 gallon batch, we’ll fine tune the mash & sparge process so we can work with both tuns at the same time. With some adjustments, I think we can easily knock off an hour.
The brew day turned out to be a big success. We were shooting for a 1.087 original gravity and over shot it; as our original gravity was 1.090!!! This is the highest O.G. beer that I’ve ever brewed. I had to make sure that I used my blow off setup as I knew this one would shoot the normal airlock into orbit. 
I’m pretty excited to get this batch fermenting.
UPDATE (11/1/11): My blog post is a touch behind so I’ll give you an update of fermentation… This beer was fermenting like crazy on Monday morning. That was a great sign as we pitched a 1000 ml starter into each fermenter. The color of the beer is a nice caramel color (so far).
Till next time, Cheers!
Eric
