Too much evaporation

[FlemingsFinest]

The other day I brewed an IPA up, and after sparging I achieved my desired pre-boil volume of 6.5 gal. I boiled for 60 minutes as usual, but unexpectedly came out wayyy below my usual 5.5 gal post-boil volume. I was all the way to just above 3 gallons! I added enough water to bring it up to 4gallons, but I can only imagine what that will do to the end result. Any ideas why this may have happened? I used the same equipment as usual. The only difference was that I used tap water for the first time instead of packaged water. Also, any idea what the end product will taste like after adding nearly a gallon of water after the boil? Thanks.

 

[Germelli1]

I am trying to figure out how you boiled off 3.5 gallons (over half your wort) in an hour.

Are you sure you didn't fall asleep and not realize it

I am guessing it might have caramelized your wort a little but I bet it will still be pretty good beer!

 

[FlemingsFinest]

Trust me, it's baffling me too lol. This is definitely a first. What's worse is that my hydrometer broke and I haven't replaced it, so I couldn't add water based on any gravity readings, simply did it blind.

 

[Misplaced_Canuck]

I easily lose 2.0 to 2.5 gallons in a 1 hour boil in a standard keggle. The air temperature, humidity, barometric pressure and even if you're in the shade or in the sun all play a role in the amount of boil-off you will have.

M_C

 

[neko]

Did you have a more vigorous boil than usual?

 

[LVBen]

The air temperature, humidity, barometric pressure and even if you're in the shade or in the sun all play a role in the amount of boil-off you will have.

More important than any of that is the flame under the pot. A hotter fire under your pot will cause more evaporation.

I don't know about you guys, but I just try to 'eye' my boil. If it looks low, I increase the heat. If it very vigorous, I decrease the heat.

It can be hard to gauge exactly the same boil each time, especially when it is windy out.

 

[shafferpilot]

especially when it is windy out.

I find that this impacts boil off more than anything! If I brew in the garage on a calm evening, I have to crank the heat and boil for a little while before the first hop addition. If it's a windy afternoon, I have to keep the heat low and still end up having to top off.

Your brew is gonna be way higher gravity than you intended. If this happens in the future, go ahead and top off back to your desired post boil volume. This will get you back to the intended OG.

 

[Misplaced_Canuck]

More important than any of that is the flame under the pot. A hotter fire under your pot will cause more evaporation.

I think you mean "how vigorous the boil is". You could have a flame that could burn off San Francisco, but if you're barely boiling, the evap rate isn't going to be too high. But, yeah, it's the same basic idea.

M_C