I have a couple questions about determining the pre-boil water volume for small batch brewing. I will be brewing several 1-gallon brews to refine some recipes. What should the pre-boil volume be with 60 minutes boils for most, 90 minute boil for one brew. How do you go about determining the amount of water needed?
I’d be surprised if there wasn’t already a thread dedicated to this. Sorry if this post is redundant. Thanks for the help!
Too many variables to be able to offer a precise answer. I’d suggest you take your pot and put in 1.5 gallons or water and see where the volume is 60 and 90 minutes later and then adjust your total volume to end up where you want it. That will also give you your boiloff rate for your setup.
Sugars are always conserved meaning whatever sugars end up in the kettle after mash will be there after the boil. You can always add water back to achieve a particular gravity if the post boil gravity is higher than expected.
Volume in fermenter = original volume – losses
Losses can be from grain absorption, mash tun dead space, evaporation during boil, dead space in boil kettle, trub, and dead space in fermentor.
Everybody’s system is different in their losses so you should learn how your system performs. Like MDixon suggested, do a test run on your system using a small volume.
There may be some other losses I’m not thinking of offhand.
What is your boiloff in gallons or liters per hour? Once you know that for your kettle/burner, you simply multiply your boiloff rate by your boil length and add that to your desired postboil volume.
^ That. Also, with a small volume a 60+ minute boil may not be necessary, or even feasible. If you’re boiling off 10-20% then you can stop, regardless of how long that takes.
I typically do 20-30 minute boils for my 1 gal batches.
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I use my calculator above to determine all my water volumes, temp adjustments, and a general efficiency to enter into the recipe formulator of choice (BS2 for me). I’ve never been more than 1/2 gravity points off my brews since I implemented the mash analysis section. Always handy to know how much mash efficiency you’re going to lose by doing a big brew, or gain by doing a smaller than usual brew.
I’ve also been doing small batches lately. Very simple and quick brew days for me. Set up and cleaning takes about as much active time as the whole brew day.
How does that affect hop utilisation in terms of the bittering addition?
I just add more hops typically.
It knocks off about 20-50% depending on whose equation you pretend to believe. Tinseth has ~23% for a 60 min boil at 1.050 and ~14% for 20 min, for example.
I guess that’s not much in a small batch… I normally do 2-3 gallon batches and would love to be able to shave off some time on my brew day.
Sorry for going off topic but I think it’s an interesting question in itself.
Even with decreased utilization I still only use small amounts of hops for a 1 gal batch and a 20 min boil