2gl Extract full boil, boil off amount.

venquessa · 02-10-2012, 07:40 AM

Is there an easy way to judge/calculate how much wort I will lose with a 30min steep and a 30min boil aiming for 2 gallons of wort at the end?

**KoedBrew** · 02-10-2012, 08:48 AM

It is hard to be exactly sure unless you and your system in certain conditions have done it before. I usually get about a 1 - 1.25 gallons an hour for a normal boil. Could be more for a rigorous boil. For what you are asking I would say about 3/4 a gallon? Just a guess though

**BamaRooster** · 02-10-2012, 02:28 PM

Quote:

Originally Posted by KoedBrew

It is hard to be exactly sure unless you and your system in certain conditions have done it before. I usually get about a 1 - 1.25 gallons an hour for a normal boil. Could be more for a rigorous boil. For what you are asking I would say about 3/4 a gallon? Just a guess though

I also get about 1 - 1.25 gallons of boil loss per hour. You could do an experiment, put 3 gallons on the boil and then measure it after 1 hour and you'll have an answer.

**ajf** · 02-10-2012, 03:20 PM

Quote:

Originally Posted by BamaRooster

I also get about 1 - 1.25 gallons of boil loss per hour. You could do an experiment, put 3 gallons on the boil and then measure it after 1 hour and you'll have an answer.

+1.

Boil 3 gallons of water for an hour and see how much you have left. Best way to judge how much you boiled off is by weight as hot water has a higher volume than it would when cooled.

-a.

frankstoneline · 02-10-2012, 03:33 PM

If you've boiled in your pot before changing the volume or time shouldnt change the boil off rate so you should lose half as much as you would expect in a 60 minute boil.
As for the grain loss its ~0.125 gallons/lb (this changes a little depending on crush, whether you squeeze drain etc).

**ajf** · 02-10-2012, 09:01 PM

Quote:

Originally Posted by frankstoneline

If you've boiled in your pot before changing the volume or time shouldnt change the boil off rate so you should lose half as much as you would expect in a 60 minute boil.
As for the grain loss its ~0.125 gallons/lb (this changes a little depending on crush, whether you squeeze drain etc).

That's true if you express the boil off rate as gallons per hour, but not if you express it as a percentage.

-a.

venquessa · 02-11-2012, 08:10 AM

Well I stuck into the brew last night without even looking on the thread. For one I realised I had no way of measuring how much water was in the pot, except to fill it with 2 5 litre demijohns worth. I filled the demi johns to the very top, which pretty much maxed out my 12.5 litre boil pot.

I was careful with how much sparge water I used, judging by eye that I had slightly less wort than water I started with and luckily(?) came up with 2 demi johns full of wort and only 1 inch above the shoulder where it starts to narrow.

Trouble is... I was drinking home brew and by the time I finished, as it took so fricking long for my stove to boil the water... I was a little drunk. I forgot an OG measurement. I put the full 11g of nottingham yeast into the wort (half in each demijohn) and of course this morning I have one runaway ferment and had to install a blow off system into a jug of water. The other one is slightly (only slightly) less energetic but hasn't (yet) started to blow foam through the airlock. If it does, I'm in a bit of diffs as I only have one blow off hose, without taking apart my bottling hose.

Musky01 · 02-23-2012, 07:10 PM

I've been searching the forums and feel like this answered my question but would like some input from someone that has done it.

I have been making 5 gal batches for the last 3 years but want to make a few test 2.5 gal using my same setup.

In a 5 gallon batch I am always at 1.25 gal/hr so in a smaller batch I should expect the same rate? Boil off is not a function of volume but of surface area? Am I getting this right?

flushdrew42 · 02-23-2012, 07:24 PM

i make 1.5gallon batches. i have a two gallon pot, when i boil, i'm boiling 1.75 gallons and ending with a little more than 1 gallon. and i top up to 1.5. in a 60 minute boil.

my first BIAB AG batch i had 3 quarts of strikewater, 1 gallon of sparge. (1.75g boil)

and needed a little more than 1/2 a gallon to hit my 1.5G line on my brew bucket.

**helibrewer** · 02-23-2012, 09:38 PM

The gallons/hr boil off is a function of the kettle geometry (surface area of liquid) not the volume being boiled. Also a pretty easy rule-of-thumb for sparge water is to use the same volume as your desired batch size...works very well.