More than 7 gals needed for 5 gal beer?

[granpooba19]

So I've brewed about 5 all-grain batches so far. The first few I did I started with 6.5 gallons pre-boil because that seemed to be the norm. It was nowhere near enough to end up with 5 gallons in the keg. The last one I did I batch sparged until I had 7 gallons in the BK. This was the first time I used leaf hops, 4.5 oz and I'm going to use 3 oz to dry hop. So I wasn't accustomed to the huge loss to the leaf hops even though I squeezed the heck out of them.

Even at 7 gallons in the BK, my last runnings were about 1.03, so I know I can get more wort out since I can get down to 1.01.

I lose a lot to evaporation because I'm doing 5 gallons in a 15 gallon Blichmann Boilermaker so there is a ton of surface area (got the 15 gal. since I'll do 10 gallon batches eventually and it seemed silly not to get it for the marginal price increase compared to buying a whole other pot later) and I'm using a turkey fryer burner which I try and keep low so it isn't a ferocious boil.

So my question is, is it OK to have like 7.5 or 8 gallons in the BK pre-boil as long as my final runnings aren't below 1.01 so that I can still end up with 5 gallons in the keg? Thanks.

 

[pelipen]

Perfectly normal. I start with 8 to target 6 in the fermentor. Just know your gravity and volume so you can adjust hops as needed.

Good choice on the pot. I also use a 15 for 5 gallon batches, just in case someday I decide to do 10.

 

[freeflydude]

I'm a plus one on that. I typically do about 8 gallon pre-boil to get 5.5-6 gallons in the primary. By the time it ferments out I've usually lost a little through the blow off tube so end up with right at 5G with trub loss. A more vigorous boil is good for the brew too so keep the heat up.

 

[william_shakes_beer]

I also got a 15 gallon blichmann for 5 gallon batches. I do Biab no sparge, which mashes a lot thinner and requires more space. Of course my very first batch was a 10 gallon. Gotta keep the pipeline full!!! I have nowhere near the kind of evap losses you have. I boil off about 1 gal per hour with a rolling boil on a KAB 4propane burner, but I use pellet hops, not leaf.

 

[BreezyBrew]

I typically do about 8 gallon pre-boil to get 5.5-6 gallons in the primary.

What size primary do you use Free? 6.5?

 

[Grannyknot]

I have a 15gal megapot and the boil off is crazy high, like 20%/hr.
I usually end up starting with 8 gallons, and getting 5.25 in the fermenter.

 

[duboman]

There is quite a bit of math involved in AG brewing and every brew will be different depending on the grain bill of the recipe. There are also losses to account for such as absorption, boil off , dead space in both the kettle and mash/lauter tun adn as you've discovered, hops.

Ideally you want to calculate strike water at 1.25-1.5qts per lb of grain. From that you can estimate .21qts/lb loss to absorption. Measure your first run volume and then calculate sparge volume for what you need to get in the kettle pre-boil. This will be determined by boil off value and dead space.

I brew 6.25 gallon batches and with all my losses I need 8.97-9.25 gallons pre-boil to get 6.25 in primary and 6 finished gallons of beer. Software is a great help and I recommend Beersmith but there are many out there.

 

[pelipen]

What size primary do you use Free? 6.5?

Yes, I use the glass 6.5 g acid carboys. 6 leaves plenty of headspace for most things. I think they hold closer 7, but I only marked up to 6.

Oh, I thought that was directed to me. Just woke up. Oops.

 

[freeflydude]

What size primary do you use Free? 6.5?

Yes, glass Carboy.

 

[Clonefan94]

I'll just add as well that this is not uncommon. I've finally determined 8 gallons to be my magic number for pre-boil as well. I boil off about 2 Gallons/hour, so this leaves me with 6 gallons to work with in the pot when transferring over to the fermentor. I usually shoot for 5.25 - 5.5 going into the fermentor. Since I use the "dump through a strainer" method of transferring wort, it leaves me some room to leave trub and hops behind.

This is what makes Beersmith great, you can plug all your numbers in there and it figures out everything for you once you figure out yoru boil off rate. Of all the research I did, boil-off was one I wish was emphasized more for beginner brewers. I would suggest for everyone's first fuill boil, you just measure out 6 gallons of water, boil it for an hour, then measure it again after it cools. That piece of information there has been invaluable for me when it comes to hitting target gravities.

The biggest problem is that every system is different. You could be using the same burner and pot as me, but our boil-offs could still not match based on environment, humidity in the air, etc. I've even noticed a big change since brewing in the hot humid summer to now, cool and dry.