Mashing/Brewing Two Beers at Once

I brew two 5 gallon batches in a weekend enough that I have been trying to figure out if I can simplify the process (and maybe leave some weekends free without killing my pipeline). Luckily, some of my brews have similar basic mash profiles (e.g., my German Altbier involves adding small amounts of specialty grains that do not need to be mashed to the grist that I use for my Kolsch), so I was thinking about combining the process. I am hoping to do this without the need to buy a bunch of additional equipment, and I have come up with the following, which would only require me to buy a 60-70 quart cooler and convert it to a MLT. Here is what I have in mind:

1. Mash a 10 gallon batch of the base beer (in the example above, the Kolsch) in a mash tun cooler.
2. Drain the first runnings into my existing 5 gallon cooler (to keep warm during sparge)
3. Sparge the mash, draining second runnings into my existing 30 quart boil kettle.
4. Dump the grain from the mash tun cooler and rinse it out.
5. Combine the first and second runnings in the mash tun cooler.
6. Drain half the wort into the boil kettle and proceed with the boil of the base beer.
7. At the same time that I am starting the boil of the base beer, I would add the specialty grains to the mash tun cooler in a BIAB bag and allow them to steep.
8. Finish boil of base beer, chill, and transfer to fermenter.
9. Transfer darker beer wort to boil kettle number 2 and proceed as usual with the boil of that beer.

Does this make sense? Am I missing something that will create problems with this approach?

It seems like with the 2 transfers and wait time, the wort for your 2nd batch would have cooled a bit. Net effect, your specialty grains would be seeping at a lower temp than the base beer.

I don't know if that would be an issue for what you're trying to accomplish.

It sounds like you save the time of 1 mash step? I don't know how long that is for you, an hour? or maybe more because you are adding a 2nd boil to they day, which is 1 hour... probably somewhere inbetween.

What you are talking about can be done, and probably make sense. You could use your 60-70 gallon HLT as your mix vessel, then save the clean up of the mash tun for while you are doing a boil. I'm just trying to see choke points. and the HLT shoudl be, well hot so you don't loose any heat for the grains that are steeping.

vlesperance said:

It seems like with the 2 transfers and wait time, the wort for your 2nd batch would have cooled a bit. Net effect, your specialty grains would be seeping at a lower temp than the base beer.

I don't know if that would be an issue for what you're trying to accomplish.

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That might be an issue, but I could address this by draining part of the wort to my second boil kettle and bringing the temperature up on my stove inside and then adding it back to the mash tun.

ACbrewer said:

It sounds like you save the time of 1 mash step? I don't know how long that is for you, an hour? or maybe more because you are adding a 2nd boil to they day, which is 1 hour... probably somewhere inbetween.

What you are talking about can be done, and probably make sense. You could use your 60-70 gallon HLT as your mix vessel, then save the clean up of the mash tun for while you are doing a boil. I'm just trying to see choke points. and the HLT shoudl be, well hot so you don't loose any heat for the grains that are steeping.

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I was thinking I would save more than just a single mash step. When I currently brew multiple batches in a weekend it is over two days, so I do everything twice. This approach would allow me to eliminate: the second set up, the second mash, and the second cleanup. These savings alone probably account for something like 2.5 hours of my time. The bigger time savings would be that I would be multitasking. I find that much of my brew day currently is spent standing around doing very little (think of all the time that we spend watching kettles heating, boiling, or cooling). I was thinking that by combining two brew days into one, I could use the down time from brew one as the time I have to actively do things for the second brew. For example, I could use the time that the first batch is cooling with the wort chiller as a chance to start bringing the second batch of wort to a boil. My hope would be that if I get good at this, I would be able to brew two batches in about 1.5 hours longer than it currently takes me to brew one batch.

You can definitely save some overall time doing double batches, its all just a matter of maximizing your efficiencies. Heres just a couple things that I think are necessary to speed up your double brew days.

You may already be planning these, so I apologize if I read your posts incorrectly:

-Have a dedicated burner on both your HLT and kettle. This allows you to be heating your next batch of water while boiling your first batch. Most efficient is if you can time it so that your first batch is coming to a boil right around the beginning of your second mash (especially if you are doing 1 hr mash/ 1hr boils).

-Keep you HLT full and firing at nearly all times.

-Think of doing a partigyle, where the first beer uses the higher gravity running and the next batch is a lower ABV. You can also add some fermentables to the second batch’s mash if you want them to be more similar gravities. This eliminates the waiting for the entire wort to runoff and separate.

kpr121 said:

-Think of doing a partigyle, where the first beer uses the higher gravity running and the next batch is a lower ABV. You can also add some fermentables to the second batch’s mash if you want them to be more similar gravities. This eliminates the waiting for the entire wort to runoff and separate.

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i just did a parti-gyle. mash-in, mash-out, take 1/3 of batch in first runnings and boiled 2 hours for barley wine, sparged, capped with some crystal/caramel and took rest of runnings and made an Irish red.

Randy Mosher writes about it here

Thanks. The parti-gyle approach is what gave me the idea. Because my brews all tend to end up around the same OG (around 1.050), I figured I could do something similar by using a single mash to create the base wort and then adding the grains that don't need mashing. That's why I had planned to combine the first and second runnings and then split the batch up. The Kolsch/Altbier combo just works perfectly because my Kolsch does not have any grains that would need to be steeped, so I could proceed straight to the boil while steeping darker grains in the Altbier wort. Long term, I definitely plan to get multiple outdoor burners so that I would be able to actually boil both batches simultaneously. In the interim, I figured that I could use the time that I am boiling the first batch as an opportunity to steep the darker grains in the second batch.

rklinck said:

Thanks. The parti-gyle approach is what gave me the idea. Because my brews all tend to end up around the same OG (around 1.050), I figured I could do something similar by using a single mash to create the base wort and then adding the grains that don't need mashing. That's why I had planned to combine the first and second runnings and then split the batch up. The Kolsch/Altbier combo just works perfectly because my Kolsch does not have any grains that would need to be steeped, so I could proceed straight to the boil while steeping darker grains in the Altbier wort. Long term, I definitely plan to get multiple outdoor burners so that I would be able to actually boil both batches simultaneously. In the interim, I figured that I could use the time that I am boiling the first batch as an opportunity to steep the darker grains in the second batch.

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rklink, i really think you have something here. What you have planned makes sense to me. Keep us informed please

JimRausch said:

rklink, i really think you have something here. What you have planned makes sense to me. Keep us informed please

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Will do. I bought and converted the big cooler last night, so I am going to brew up a Kolsch/Altbier combo this weekend.

As an update, I did the double batch brew yesterday. The actual mash/brew went well. The biggest hiccup was that I had misplaced my digital thermometer and spent about an hour cussing and searching my house before I found it and could get started (Note to self -- prepare everything for brew days the night before).

The whole process took me 8 hours from dough in to both beers being in fermenters and my equipment soaking in PBW. The reason it took so long was that I decided to try a modified triple decoction mash (doughed in at 133, stepped to 145, stepped to 155, mashed out). I was not done with the sparge until close to 5 hours in. I also tweaked my boil approach slightly. After the first beer had been boiling for about 30 minutes on the outside burner, I transferred it to my stovetop to finish the boil. At that point, I stared heating the second batch on the outside burner, which is stronger. Both beers finished with OGs within .002 of targets, so I am hopeful.

Between the double batch and the triple decoction, I definitely did no have much free time during the day. Luckily, my wife was around and willing to run downstairs from time to time to fill my pint glass and get various brewing implements.