Boiloff-effects

[dave althouse]

OK, the more I read the more questions I have. Boiloff, the amount of liquid lost during your boil. What is the loss, water? So if you target is to have 3 gallons go into the fermentor and you have 1.5 gallon boil off during the process can't you just start off with more 1.5 gall more water? Or can I just leave a lid on it and catch as much of the condensation that I can. Does that effect OG, IBU. I know on my last batch the receipt OG and my OG were off. Wonder if water adjustment throws that all off. The several batches that I have made I always have pre-boiled water to top off to my 5 gallon level.

What is correct? I don't know...input welcome

davea

 

[LarryBrewer]

Yes you want to plan for the boiloff losses. The recipe editor takes that into account. There is a field for batch size and one for boil size. If you then check the recipe tools -> quick water requirements you'll get even more details.

Don't cover the boil, that traps undesirable compounds. Boil with the lid off.

Each kettle has a different boil off rate. Mine is wider than most. My equipment profile is set to 5.5 qt / hr. You may want to do a test to know for sure with yours. It also depends on how hard you boil. I get it to a rolling boil then dial it back some, but it is still moving pretty good.

 

[dave althouse]

so then let me ask this, my goal is to has 5 gallons of wort in my primary. what affect does the amount of water I start with have on the final product. Lets say I start with 4 gallons of water, steep my grain, add lme/dme and top off to 5 gallons.....or.....start with 2 gallons of water, then top off to five gallons. Will these variations have an impact on the brew? Got to ask 'cause I just don't know

 

[Ozarks Mountain Brewery]

your goal should be 5 gallons finished beer, you can lose 1/4 to 1/2 a gallon in the fermentation vessels the amount before the boil isn't as important as the final volume at the start of the boil, as he stated you should test at least one time how much boil off you get from your boil then add or subtract from there

I always shoot for 5 1/2 to 6 in the primary, you probably will need at least 5 1/2

to answer your question, either doesn't matter

 

[LarryBrewer]

For extract brewing, if you end up with 2 gallons in the kettle, or 4 gallons in the kettle and top off from there, that means you had a different boil size.

Since you are diluting to the same final volume, the OG will always be the same (given the same amount of LME/DME going into the kettle).

Boil size impacts boil gravity (how concentrated the sugars are in the kettle). That impacts IBUs. In the IBU equations we use, boil gravity is taken into account. The higher the boil gravity (eg, the lesser the boil volume), the harder it is for the hop alpha acids to convert to bittering flavors. That factor is called utilization. If you change the boil gravity in the recipe editor from 2 gal to 4 gal, you should see a jump in IBUs. In general, extract brewers who do a partial boil need to use more hops to get the same level of bitterness as all grain brewers. Extract brewers should note their boil volume so they can be consistent brew to brew, especially if they try to brew the same recipe again.

The other factor is how the top off water will impact the final beer. If it is just tap water, and it has a noticeable chorline smell or flavor, that will come through in the beer. The more top off you use the worse it will be. That is one of the major benefits of doing a full wort boil. The other is fully sanitizing the wort in the kettle. A wort chiller is needed though to cool down the wort quickly (yeah another thing to buy).

My advice is to do the largest boil you can to get the most out of your hops, and reduce impacts from off flavors in the top off water.

 

[Ozarks Mountain Brewery]

when I posted that I was thinking you topped it off then boiled, my mistake I'm not an extract brewer lol

 

[chessking]

In general, extract brewers need to use more hops to get the same level of bitterness as all grain brewers.

Minor correction. I know what you mean Larry, but just so Dave can understand better.

Extract vs all grain is not the issue, but partial boil vs full volume boil. If you boil extract at full volume the utilization is the same. A concentrated boil hinders utilization, requiring more hops to achieve the same IBU level. One way to overcome this is a late addition of extract. Add about a third of the extract at the start of the boil, and add the balance at the end of the boil (last ten minutes or so). The extract needs only to be sanitized.

 

[LarryBrewer]

Thanks, updated my statement above. Yes, late additions mitigate this to a great extent. Good catch!