Acceptable Loss and Gravity question

[ChefJoeR]

When boiling the wort, how much would you consider to be an acceptable loss? 5% loss, 10%? This is my second brew, and from my restaurant experience, when you boil a liquid for 1 hour, you will have a substantial loss. In the restaurant, we don't boil stock (sauce/soup bases) for that reason, we are looking to extract the flavor, and keep loss to a minimum. I boiled 2 1/2 gallons and came up with a final amount of about 1 3/4 gallon. Did I boil too hard? I am making a pilsner. Also my original gravity was at 1.052, my recipe says it should be between 1.041 - 1.046. Any comments on this? Thanks all.

 

[Netflyer]

Well, I'm assuming, possibly wrongly, that your 2nd brew is an extract brew. The final gravity of the extract brew should have been between 1.041-1.046 after you add water to get you the final volume stated by the kit. Did you add water after you boil to get to that stated final volume and then was your gravity still too high?

If you went below the final volume that would easily explain it. As you boil you concentrate your wort and the gravity. I do full boils and if I'm aiming for say 1.052 my full boil starting gravity might be say 1.033, I boil off a few gallons and I'm at my 1.052. For you it is most likely going the other way. You start with a concentrated wort and then dilute to your final volume to achieve your final gravity.

If you have a large pot and are already doing full boil extract batches then you went too far and concentrated the wort too much. Still you can add water back and get you to your desired range. Btw the beer will probably be fine at 1.052 - I wouldn't worry too much

Typically between 5-15% loss of water due to evaporation can be expected. This varies because depending upon the external environment and frankly the shape of your pot (tall and skinny or big and wide) more or less surface area is constantly exposed. When I brew outside in 17F and it is breezy I can lose 20%! On a very still day with some humidity in the air I can lose only 5%

Hope this helps answer your question!

 

[jkarp]

Percentage is nearly meaningless as 5% of a 5 gallon boil is very different than 5% of a 10 gallon boil. A given system will boil off x gal/hr where most homebrewers shoot for an x between .75 and 1.5. Looks like you're in the range. More importantly, the boil must have a sufficient "roll" to self-circulate and volatilize off any DMS precursors.

 

[shortyjacobs]

+1 to what jkarp says. It's gallons/hr of boiloff, regardless of pot volume.

 

[IrregularPulse]

yep. It' snot a percetnage. It's so many gallons per hour regardless of starting size. Using the same flame and same pot and same environment will give the same boil off.

 

[Ohio-Ed]

yep. It' snot a percetnage. It's so many gallons per hour regardless of starting size. Using the same flame and same pot and same environment will give the same boil off.

So on a cold day when there is more "snot", do you boil of more or less?

 

[ChefJoeR]

So when it comes down to it, it seems that I really have nothing to worry about, hopefully. Am assuming that my final gravity will also be in the higher than stated range? If so, is there a way to correct this, or do I just leave it be and hope the beer comes out tasty. I will try to get the recipe up this afternoon or evening so you can give me your opinions. I do 2.5 gallon batches, I don't have room for a full 5 gallon set-up and all the equipment. Getting to it later, have a "honey-do" list first and it's a big one! Thanks for all the help.

 

[pkeeler]

Am assuming that my final gravity will also be in the higher than stated range? If so, is there a way to correct this, or do I just leave it be and hope the beer comes out tasty.

The Gravity is just the specific gravity of the water (SG). In this case, it relates to the amount of sugar in solution. You can increase gravity if needed by adding sugar (DME, corn sugar, maple syrup, honey, etc.) and you can decrease gravity by adding water. You can also increase gravity (but reduce volume) by boiling.

If you are within a few points either side of your target there is no reason to worry.

 

[Netflyer]

% is meaningless??! 'It's about gallons not %' ... what? Same difference guys. x gallons is also y%. Just a different way of saying it. If I know I'm going to lose 5% or .5 gallon on 10 it's the same difference. You can state your loss however you want but whether you measure it in gallons or % it doesn't matter. Yes, given the same environment and same equipment, same wort, and same flame your loss will be x gallons and also y% of your boil - either way, same thing. For me, who brews out in the elements my loss is always different due to evaporation because my environment is always changing. My loss is also different depending upon the wort I'm brewing and what my base grain is.

 

[Netflyer]

So on a cold day when there is more "snot", do you boil of more or less?

Well if you boil for the same amount of time less is left, that's for sure. Cold dry air will take more moisture but what really matters is if there is a breeze... a breeze will take the surface off the wort in conjunction with the rolling boil and the evap will go way up.

I brewed the same recipe at 17 degrees and at 70 and my loss to evap. was 20% in the cold and about 8% at 70. Same equipment, same batch just different external environment.

 

[shortyjacobs]

% is meaningless??! 'It's about gallons not %' ... what? Same difference guys. x gallons is also y%. Just a different way of saying it. If I know I'm going to lose 5% or .5 gallon on 10 it's the same difference. You can state your loss however you want but whether you measure it in gallons or % it doesn't matter. Yes, given the same environment and same equipment, same wort, and same flame your loss will be x gallons and also y% of your boil - either way, same thing. For me, who brews out in the elements my loss is always different due to evaporation because my environment is always changing. My loss is also different depending upon the wort I'm brewing and what my base grain is.

Not quite Netflyer. The point is you boil off the same amount, regardless of boil volume.

So, if I start with 6 gal of wort, I boil off 1 gal, or 17%.

If I start off with 11 gal of wort, I ALSO boil off 1 gal, or only 9%

If I'm boiling 16 gal of wort, I STILL boil off 1 gal, or 6.25%.

Same boil off in gal/hr, but different in percent. See?

This is true as long as the pot/burner/flame/environment is the same.

 

[Netflyer]

Of course but it is not meaningless as it pertains to your equipment. Of course it is meaningless to compare my equipment to yours on the same day. We would of course have different % losses. My point is you need to know either the amount of gallons or the % of loss with your equipment.

If you guys are trying to say that saying 5% loss could be considered standard I totally agree with you as it would vary with equipment but so would gallons...

 

[shortyjacobs]

Of course but it is not meaningless as it pertains to your equipment. Of course it is meaningless to compare my equipment to yours on the same day. We would of course have different % losses. My point is you need to know either the amount of gallons or the % of loss with your equipment.

If you guys are trying to say that saying 5% loss could be considered standard I totally agree with you as it would vary with equipment but so would gallons...

Not quite.

With MY equipment, I boil off around 0.7 gallons per hour. When I make a 5.5 gallon batch with MY equipment, I boil off 0.7 gallons per hour, or about 11%. With the SAME equipment, if I make a 11 gallon batch, I STILL boil off 0.7 gallons per hour, or about 6%.

Same equipment, same gal/hr boiloff, DIFFERENT % boiloff.

 

[mkling]

This is my second brew, and from my restaurant experience, when you boil a liquid for 1 hour, you will have a substantial loss. In the restaurant, we don't boil stock (sauce/soup bases) for that reason, we are looking to extract the flavor, and keep loss to a minimum.

The crucial thing to remember here is that you want a good rolling boil here. It helps with IBU extraction from your hops, melanoiden production in the wort, drives off DMS, and does just a whole lot of good things to the chemistry of your wort to make it better beer. A good rolling boil will make your beer better and you should do what you need to to have one. That could mean starting with more water than you want to end with or adding boiled, cooled water post-boil to get the final volume you want. But don't view this like you do with stick in the restaurant business -- the active rolling boil changes the chemistry of your wort to make for better beer.

 

[jkarp]

+1 mkling.

The problem is, noobs don't always know what a "good rolling boil" is and they come here asking about boil-off. Further adding to the confusion is that so much of the brewing software out there is bone-headed in using percentages, which makes the noobs thing they can compare % with other users. It's always best to keep things simple by working in gal/hr. Then the brewer can convert to % for their own system if desired.

 

[bigjoe]

I don't think % in software is a good idea eihter. The percent will be the same for any given volume but not from one volume to the other as has been noted. So percentage on your own equipment will vary, but not the constant evap rate.

Someone mentioned you'll need to know your evap rates and adjust the recipe pre-boil volumes based on your own evap rate. I boil off about 1.5 gallons per hour and .7 gallon a hour by others. So I evap twice as much as they do and would end up with a higher starting gravity if I followed the recipe exactly as they brewed it.

 

[Netflyer]

The software uses %evap to help you calibrate your boil volume on a given day with given equipment. It could just as well ask you how many gallons you will lose. Either way you have to estimate if you're changing your environment.