Batch size vs. boil size

I saw a 2 gallon recipe for a Marzen on Brewgr.com, and it said the boil size was 4 gallons for a 2 gallon batch. How can you boil more than the batch?

Thanks,

Gonzo

You will lose volume durnig the boil due to boil off. I need 8.75 gallons of wort to end up with 5.75 going into the fermrnter. That is mostly due to the fact I boil using a 15 gallon kettle so I have a large surface area. I loose 3 gallons during the hour boil. I think normally with smaller kettles or taller narrower ones you would loose a gallon or so. Not to worry, you are only loosing water, not all the good stuff needed to make your beer.

It actually goes beyond just boil off. You also loose volume in the fermentor when you rack off the trub. I’ll typically calculate my recipes for 7.9 or 8.5 gallons going into the kettle (depending on boil length) to get 5.5 gallons into the fermentor so I end up with 5.25 gallons of finished beer. And you DO loose some of the good stuff with the trub, so I’ll calculate ingredients based on the 5.5 gallon volume.

I figured it was something like that, but didn’t think you could lose that much water over the boil. But, now that I think about it, it explains why I only got 5 bottles out of my first gallon batch.

If that is the case, it should have been much stronger than expected.

Hoping to piggyback here. Anyone tried splitting a 5 gallon batch between 2 fermenters? I’m looking to try splitting a blonde ale recipe that calls for fruit additions once in the pri-fermentor. I was thinking of splitting to do 2 different fruits. My concern would be head space in the pri- and sec- fermenters. Any advice? Thanks in advance!

I brew 2.5 gallon batches occasionally and ferment them in 6.5 gallon buckets with no problems. Once it starts fermenting the head space will quickly be filled with co2. I don’t do secondaries but the extra head space in a 5 gallon carboy might pose a problem.

I’m still a newbie, but I was lead to understand that the residual yeast in suspension is still working, albeit slowly, and creating CO2 that cushions the wort from any O2 as it fills the headspace in the secondary.

I’m still a newbie, but I was lead to understand that the residual yeast in suspension is still working, albeit slowly, and creating CO2 that cushions the wort from any O2 as it fills the headspace in the secondary.[/quote]
Not really. Yes, there is still activity from the yeast after the primary fermentation is done, but it isn’t enough to create an effective CO2 blanket. That said, if you only keep the secondary for a few weeks and plan to drink your beer within a few months, you are very unlikely to see problems from oxidation.

Back to the origional topic: the amount of water that gets boiled off is very dependent on your set-up, so you can’t just go by a recipe. I use to loose about a gallon for a one hour boil when I was using a small kettle for extract batches on my stove. I loose much more from my big kettle on my outdoor burner now, but that isn’t a problem because I’ve measured the rate of boil off and can plan for it.

Thanks all, especially to Gonzo for allowing me to temporarily hijack his post :slight_smile: Cheers!

Is anyone else LOSING their mind over how often people are writing “loose” instead of “lose” in this thread? :lol: Not really important, but it bothered me.

not really, I lose it over the misuse of your/you’re!

How about PALATE? I keep seeing palette. What, are there a bunch of painters around here? :lol:

As a former state spelling bee competitor, I notice a lot of misspellings, but nobody likes a nitpicker. :cheers: