Boil Evaporation?

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natemtb

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I would like to do a full 5 gallon boil on my next batch. I was wondering if any of you guys know how much water I need to start with? 60 min. Boil, 70 quart pot, ambient temp 45-50 degrees f. Is my pot big enough? Should I add water as I go or put it all in from the beginning?
Or any other tips and suggestions?

I did a quick search but my doing it on my phone I couldn't find much. Thanks in advance for your help and input!
Thanks,
Nate
 
6.5-7 gallons you take boil off and trub that should get you 5-5.5 in the ferm. You may have to adjust this on your next brew so take notes. There is no formula for all I have a boiloff rate of 1.5gph and that took several brew days to dial in.
Also never forget that if you have to much wort after 1 hour continue boiling until it gets to where you want it. I regularly do 90 minute boils.
 
I start with 6.5 and am usually very close to 5 after all the transfers, tubing, etc. Your methods will vary, of course, but 6.5 is a good starting point to account for evaporation with a decent rolling boil.
 
The actual evaporation rate depends on your pot dimensions, and how hard you boil. So as others have said, start with 6.5. But after 60 minutes, be sure to make a note of the new level of the wort in your pot. That way you'll know the % you boiled off, and you will be able to properly estimate the amount you would need for a longer boil. Or a different sized batch.

FYI - the humidity in the air matters. When I boiled in the garage, in the winter, on a cold dry day, I boiled off a full extra gallon. So if you happen to be outside in the winter, you may want to up your starting wort a little bit.
 
I found out the hard way that when using a full boil size pot, I need to add basically the amount of water to start with that equals the wort I want to end up with. The kit can and extracts need to be taken into account and they will raise the quantity a good amount. If I was using grains, the water would probably increase due in part to the boiling times.

And don't forget to scratch a line for the final wort quantity on the inside of the pan. Also marking 5 gallons and 6 gallons is helpful too.
 
I usually lose about 1 gallon in the summer months and 1.5 gallons in the winter months. Just depends on your pots liquid surface area, boil rate, outside humidity, etc... it'll take a few brew days to dial down. I would shoot high at first, say around 2 gallons or so, then time the rate of boil off to help with future brews. This way you can always boil down to your desired gravity. You could also just put a few gallons in your pot and boil for an hour just to calculate your boil off rate. It may cost a little bit in propane, but save the risk of ruining a good brew day.
 
So if you measure wrong and are short a gallon in your carboy, what effect is it gonna have? can you add more water after fermentation?
 
AdamPag said:
So if you measure wrong and are short a gallon in your carboy, what effect is it gonna have? can you add more water after fermentation?
Click to expand...

Don't water down the fermented beer. Add water to the carboy before you pitch the yeast.

By shorting the water, you are strengthening the beer. It could be enough to affect fermentation to where you may need more yeast.
 
AdamPag said:
So if you measure wrong and are short a gallon in your carboy, what effect is it gonna have? can you add more water after fermentation?
Click to expand...

The only way to know is to check the gravity. If it is high you can add water if it is correct or slightly low I would not add. If it is real low you can add a little DME to bring it up.

EDITED this is all done BEFORE fermentation.
 
hm, My carboy LOOKS low a little bit, but my SG reading before fermentation was 1.047 which is .003 low. heres a pic

IMAG0009.jpg
[/IMG]
 
AdamPag said:
hm, My carboy LOOKS low a little bit, but my SG reading before fermentation was 1.047 which is .003 low. heres a pic

IMAG0009.jpg
[/IMG]
Click to expand...

Does not look low to me. Looks like you have 5.5G in a 6.5G carboy.

Next time it is empty, it is definitely worth it to measure out Gallon increments, or half gallon increments, and use a market on the bottle so you know the actual amount in the carboy.
 
its actually a 5 gal carboy, I definately noticed the same .5-1 gal reduction during the boil so It was a little tough to eye ball how much water to top off, I might be a quarter gal low. but yea, .003 is damn close so I wasnt concerned with the OG and just said LETS ROCK, Prost.
 
I bet it isn't very low and after the usual blow off you would get if you filled it up, we're probably not talking 30-40 oz low.

Is it just me or does that airlock seems extra huge?
 
I might hook it up with a mini skirt and some lipstick and see if she slims down after a few drinks
 
luke2080 said:
The actual evaporation rate depends on your pot dimensions, and how hard you boil. So as others have said, start with 6.5. But after 60 minutes, be sure to make a note of the new level of the wort in your pot. That way you'll know the % you boiled off, and you will be able to properly estimate the amount you would need for a longer boil. Or a different sized batch.

FYI - the humidity in the air matters. When I boiled in the garage, in the winter, on a cold dry day, I boiled off a full extra gallon. So if you happen to be outside in the winter, you may want to up your starting wort a little bit.
Click to expand...

i did a little experiment yesterday, in my condo, on my gas stove with the power burner. temperature inside my condo was around 66F, with barely any humidity (were constantly dealing with it being too dry in the winter months).
i put 3 gallons water in my American Kitchen Commercial Stock Pot, 20qt | Williams-Sonoma boiling kettle.

after 60 minute boil, i lost a half gallon of water, down from 3.0 to 2.5 gallons.

physics gurus... is this is a linear relationship? if i repeat the experiment with 4.0 gallons of water and boil for 60 min, will i end up with 3.5 gallons? or will it be a greater evaporation loss with a larger volume of water? if so, what is that constant?
 
pkgmsu2000 said:
i did a little experiment yesterday, in my condo, on my gas stove with the power burner. temperature inside my condo was around 66F, with barely any humidity (were constantly dealing with it being too dry in the winter months).
i put 3 gallons water in my American Kitchen Commercial Stock Pot, 20qt | Williams-Sonoma boiling kettle.

after 60 minute boil, i lost a half gallon of water, down from 3.0 to 2.5 gallons.

physics gurus... is this is a linear relationship? if i repeat the experiment with 4.0 gallons of water and boil for 60 min, will i end up with 3.5 gallons? or will it be a greater evaporation loss with a larger volume of water? if so, what is that constant?
Click to expand...

I'm not a physics guru (or homebrewing guru for that matter!), but from everything I've read here, the volume won't matter. If you use a kettle that is bigger in diameter, however, that will most likely increase the boil off rate (due to increased surface area).

I actually just did a boil off test the other night; temp in the kitchen was around 66 as well, humidity felt very low, I boiled off just a hair over 1 gallon in 60 mins.

Kosch
 
I would imagine a vigorous boil will boil off more than a simmering boil, too, although I've not tested it.

My set up has almost always lost about a gallon and a half - (propane burner, 10 gallon Polarware, outdoors) - may be a bit less
 
maffewl said:
I usually lose about 1 gallon in the summer months and 1.5 gallons in the winter months. Just depends on your pots liquid surface area, boil rate, outside humidity, etc... it'll take a few brew days to dial down. I would shoot high at first, say around 2 gallons or so, then time the rate of boil off to help with future brews. This way you can always boil down to your desired gravity. You could also just put a few gallons in your pot and boil for an hour just to calculate your boil off rate. It may cost a little bit in propane, but save the risk of ruining a good brew day.
Click to expand...

the problem with this is you might end up with way too many IBU's for your recipe if the time needed to boil down is extensive.
 
mcaple1 said:
the problem with this is you might end up with way too many IBU's for your recipe if the time needed to boil down is extensive.
Click to expand...

I agree... I would go with just plain water for an hour and figure it out. Oh... and there is no such thing as too many IBU's. ;)
 
true true....but at a point if you end up with an 80 IBU pale ale vice the intended 40-50 IBU as a direct result of boiling an extra 30-60 minutes you might be in for quite a zinger.
 
maffewl said:
I agree... I would go with just plain water for an hour and figure it out. Oh... and there is no such thing as too many IBU's. ;)
Click to expand...

yea, for real. i thought the whole point of everyone getting back into home brewing was so they could all their make their own version of an imperial double IPA :D :tank:
 

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