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Boil Evap Loss

I’m making an AG batch today and doing my boil outside in garage at about 40F. Does the ambiant temp impact my boil loss?

That’s a good question! Personally I don’t know, but I would think so. I would think hot boiling wort would evaporate quicker into colder, drier air.

Ambient humidity has the biggest effect upon evap loss. I really notice it when I make a BW and boil 30 gallons down to 15. At some point, I have to air the garage out a few times.

I actually was just searching on the web about this. Yesterday had just over 7.5 gallons in the kettle, and after a 90 minute boil, only ended up with 4 gallons in the fermenter as opposed to 5.75gallons. It really stunned me.

Temp outside was creeping near 35 degrees during bulk of boil.
Some people were saying that it was the temperature, while others were saying that it had something to do with the humidity.
I just checked, and the humidity for me was 92% at its peak yesterday.

After seeing that, I would be willing to agree that the humidity affected my end volume. I ended up diluting the wort, but only with .5 gallon distilled. At the end of the day, the Bock will be stronger than I had planned, but nonetheless should turn out just fine.

[quote=“HummelBrew”]I actually was just searching on the web about this. Yesterday had just over 7.5 gallons in the kettle, and after a 90 minute boil, only ended up with 4 gallons in the fermenter as opposed to 5.75gallons. It really stunned me.

Temp outside was creeping near 35 degrees during bulk of boil.
Some people were saying that it was the temperature, while others were saying that it had something to do with the humidity.
I just checked, and the humidity for me was 92% at its peak yesterday.

After seeing that, I would be willing to agree that the humidity affected my end volume. I ended up diluting the wort, but only with .5 gallon distilled. At the end of the day, the Bock will be stronger than I had planned, but nonetheless should turn out just fine.[/quote]

You never know. It may turn out to be great. In which case you’ll have to try and repeat it next time. I did this on a recent batch. It was a beer I was brewing for the 3rd time. Been tweaking the recipe each time. Well, this time I started drinking early (starting to learn that’s a bad idea) and ended up making a few mistakes. Splashed hot wort all over my kitchen. Made up for it by adding more water and a little extract near the end of the boil. Also forgot to add some orange zest I planned on adding at the 10min mark. Noticed it as the wort was chilling. So i pulled about a qt of wort and reboiled adding the zest. Then poured it back into the cooling wort. In the end, it’s the best batch of this particular beer I’ve made. Now I’m wondering if I need to go through all the crazy steps to get it this good again?

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